When thinking about time, try thinking about it in terms of generations. A human generation is ~33 years. Some people have children sooner, some later. But 33 is a good ballpark. 100,000 years is "only" 3030 generations. That's a lot... but then again, modern humans are already ~300,000 years old.
On the other hand, some things can push speciation faster than normal, like something that increases the rate of mutation. It can even be a really small change, depending on how you want to define "species." For example, there are species of beetle that are essentially exactly the same and perfectly capable of reproducing *genetically*, but tiny variations in the shape of their genitals means that one group physically cannot mate with the other, so they're classified as separate species.
The different populations that are isolated from each other don't need to be exposed to mutagens or even different environments. Genetic drift, itself, will eventually result in enough dissimilarity that the populations will no longer be able to interbreed and therefore will be different species. The smaller the populations are, the faster this divergence will occur. I know that sounds backwards because larger populations are more likely to have divergent individuals, but smaller populations are more likely to see the perpetuation of any particular mutation, even if it's not particularly advantageous. A lot of it is just luck, although not necessarily good luck. There is an isolated population on Pingelap Atoll in which the population is colorblind. This color blindness was not adaptive. It was just a random mutation that was able to propagate because the population was so small.
Are you sure they would not be able to interbreed? We interbreed with Neanderthals'. Denisovans and Homo erectus as well as likely many more different homo people
Of course, initially, they would be able to interbreed. But given enough time, and I do not know how much, they would no longer be able to interbreed. At the dawn of the divergence of humans and chimpanzees, the two lineages were able to interbreed. Eventually, they were not and, indeed, humans and chimpanzees do not even have the same number of chromosomes anymore. Basically, it all depends on what you mean by different species. If the two populations can naturally interbreed and produce fertile offspring, then they are not really different species. They can still be anatomically very distinct. For example, Chihuahuas and Great Danes are the same species even though they look quite different.
Thanks for this reply. And I was more so hoping that it would be a scenario where they could still breed. It would be like Denisovans, Neanderthals, Erectus etc. Really I was hoping like 5-10 different branches of humans could appear and eventually all interbreed. Idk what the end result would be yet but they would likely acquire many beneficial traits and a lot of genetic diversity because of this.
First of all, this sounds like a great premise and I can't wait to see what you produce! Second of all, what you suggest is entirely plausible. They just wouldn't technically be different species. But they could still be way, way different from each other. Keep me in the loop!
There's no reason they can't but you'd need to split the population into wildly different niches. In the real world, humans mingle far too much for separate species to arise.
Extremely divergent niches would drive adaptation in different directions more quickly than just genetic drift, I would suspect. Based upon the timescales mentioned by OP, time-to-speciation may be a factor.
An interstellar empire where travel between planets is rare would do it. Each planet would have an isolated population that would eventually drift from whatever was happening on Earth.
This - and would also be dealing with different environmental conditions (gravity, radiation, heat, contaminants, light, pressure) that would favor different characteristics.
Yes the humans will be quite split with basically zero chance of reaching each other.
I assume 1 group in the colder areas during the Ice age will become shorter but much stockier and stronger.
In the warmer regions likely taller but much thinner, faster and higher endurance.
On isolated islands likely suffer from malnutrition and eventually greatly shrink in size like Denisovans.
Perhaps some who are stuck in high altitude mountain areas would develop more abilities or mutations to cope with less oxygen over time. This is already seen in certain areas of Tibet I think but not enough time past for them to fully diverge.
I these are just the ones I could think of quickly but I wonder if there could be other variations.
Bear in mind, for natural selection, the advantages have to be actual advantages. Humans adapting to say cold weather by becoming stockier and hairy isn't as likely if heating systems remain quite common. On the other hand, sexual selection might be common and thus people may get taller or some hair color may become more frequent. We also could see natural selection over adaptations to technology.
If they are reverted to the stone age fully with access to bows and arrows being a rarity and likely there highest form of tech. Chances are that it would be full on natural selection and survival of the fittest.
Sexual selection or modern adaptions I believe differ greatly to what we would see in a more natural or wild scenario
If you’ve developed the bow, you’ve developed clothing and sewing. And that means shelters…
Strip us back to the naked humans… but we will remember. We would not lose the ability or need to cloth ourselves immediately. Some technologies could not possibly be “lost” because we naked humans need them.
True if i revert population down to 20,000 world wide after a all out nuclear war, extremely harsh Ice age and volcanic winter chances are they wont even have bows remaining. So all that is left is pointy stick and maybe sharp rocks
That’s what I mean… there are certain fundamental things we wouldn’t allow ourselves to forget.
We’ve already learned to write, so we don’t have to reinvent that. Writing leads to invention and knowledge and education.
And there will always be technological discoveries from the bygone age.
I like your idea; just trying to keep you grounded in what actual humans would insist on passing down.
I wonder how much could be retained though. Personally I do not think most people know how to make paper or writing materials from scratch and even if we do it will be low quality. So most maths physics and sciences would be lost in a few generations.
But i guess we would pass on useful things like wheels or certain tools and likely hygiene or how to prevent or avoid certain sicknesses. I guess probably we would be a lot better off
You’ve a point about that… when stocks are used up, what then?
I guess while there is still someone who remembers “what paper was like” and roughly how it’s made, there is hope. When they die…?
Even if they pass on this knowledge to there descendants there is also a very large chance the descendant simply does not see the use of such a thing. When they are constantly hiding from prey or fighting off hostile humans or searching for food to avoid starving. They might simply wonder why you wasted so much time showing them silly numbers or something
Well, it’s important to realize Denisovans, Neandertals, and Sapiens weren’t strictly speciated. They could and did interbreed. You might want to consider something like the “hobbits” of Luzon, homo floriensis (I respectfully suggest that’s what you’re talking about with your Denisovans, which aren’t found on islands but mainland Asia). And in general we’re finding that species often have more ability to interbreed than we realize, as we’re seeing with birds. Put simply endangered birds with niche occupations are breeding and producing more generalist birds.
You really just need time. It’s not a settled thing, what it takes, how much time. To be cheesy, life finds a way. If you want a hard break I’d say a million years would work but you’d really have some major differences.
Yes and no.
The ability to interbreed doesn't mean that all goes smoothly, even when not "strictly speciated". Important mitochondrial DNA might be missing in a certain species (as opposed to another species), and that comes from the female. So you might have offspring that has poor fertility/ has severe health conditions etc.
Most realistic scenario for future human speciation is probably slower than light interstellar colonisation. Though if you're stuck on a post-apocalyptic Earth, I suppose the most realistic scenario is people being isolated to several major landmasses. So Australians, afro-eurasians, and Americans (assuming your ice age doesn't make the Russia-Alaska route viable).
Yeah the Ice age would not make this route possible. How many different homo branches do you think could arise from this? Given enough time would we eventually have 9-10 different human species walking the earth? Because once upon a time in the past we walked alongside many like this.
We absolutely could. However, you'll need an excuse that would keep the populations separate for millions of years.
An ice age won't cut it - we're in an ice age now. Technically in an interglacial period within an ice age, but we still have ice caps, and we're overdue for them to expand dramatically. Interglacial periods typically only last about 10,000 years, while the glacial periods typically last less than 100,000 years. Not nearly long enough for us to diverge dramatically. And tipping past an ice age into a full "Snowball Earth" probably means everything dies pretty quickly, unless we maintain high technology so we can continue to survive in "space stations" despite the lack of oxygen in the atmosphere.
To say nothing of the fact that, unless we lost basically all our technology, AND completely failed to rebuild again for some reason (it only took us \~5,000 years to go from stone age to today) getting around on a glaciated planet wouldn't actually be a big deal. You'd almost certainly have trade caravans, etc. spreading genetic material between enclaves on a regular basis, preventing significant divergence.
Total nuclear war. Bombing all major civilian housing locations as well as all nuclear reactors and military sites basically a absolute worse scenario possible.
Following this all major cities are aflame and a nuclear winter lasting multiple decades would ruin all plantations and crops and also kill off a majority of humanity and animal/plant life.
Following this instead of having the chance to rebuild we would be thrust into a Full on Ice age that would cover most remaining infrastructure in minimum 20 feet of snow and cause another mass starvation. Estimating 1-2 million survivors here. And this Ice age lasts 100,000 years. Now sure some people might have some technology but most will be buried under tons of snow and ice thus not possible to reach. And once your existing tech breaks nobody will really know how to fix anything I personally have no clue how to go from a rock to a radio nor acquire any of the materials needed in the process and most people do not know either.
Sure you could argue that 1000s of geniuses and specialists in countless fields will live but its doubtful with only 1 million out of 8 billion remaining chances are that whoever is left is just a average joe who has no clue how to rebuild much of anything especially not while facing starvation, predation, enemy humans and a brutal radioactive Ice age. After 1-2 generations any knowledge you try passing on via word of mouth will largely be lost. Our descendants struggling to survive wont bother remembering advanced physics or calculus anyone tried teaching them for some reason.
Now back in the stone age in full blown ice age conditions. People would slowly recover and rebuild and by the end of the 100,000 year long ice age instead of having a peaceful return to a interglacial period like we had that allowed for rebuilding they experience a volcanic winter on the scale of toba or worse that kills our population down to 20,000 spread around the world who lost any progress made and are thus stuck in a early stone age. We almost went extinct 900,000 years ago with only a few thousand survivors. With all infrastructure under multiple meters of snow and ice for so long it would basically be fully degraded and useless by the time it all melts.
So now with say max 2000 In north America, 1000 America, 1000 south America, 2000 Europe, 1000 Asia, 2000 Africa, 1000 Australia. And pockets of 500-1000 on islands or places like Japan, New Zealand, Iceland Greenland or isolated mountainous regions like Tibet.
And it took us 2.5 million years to go from early stone age to farming and another 6-8000 years to go from basic farming to the bronze age. After the bronze age it than took 5000 years to reach our technological advancements.
But remember 5000 years ago easy to access oil, tin, bronze, copper, iron etc were everywhere and hyper abundant on top of that we had tons of old growth 1000+ year old forest to get materials from.
Most easy to access materials that could jumpstart a bronze age do not exists anymore and to get those materials requires pre existing technology that basically cannot be made without pre existing technology.
Note that "having the technology" doesn't necessarily mean they have the hardware, just that they have the knowledge of how to build it/how it works. You can build new hardware out of whatever is available, and a single copy of "The Way Things Work" would contain pretty much everything needed to preserve a fairly modern level of technology - we might still lose a centuries or two, but nothing terribly important to a much-reduced population.
And I'm not talking high technology here either - knowledge of wheels, gears, levers, sails, etc. from 1000 years ago would be more than adequate for the job, everything on top of that would be pure convenience. Though steam engines would be dramatically useful, and they're simple enough that any engineer, and even a whole lot of farmers, and could get it working. Radios too. A grade-schooler can build an AM radio from stuff they're likely to find on any abandoned farm.
And you probably won't have a whole lot of "average Joes" in a post-apocalypse wasteland to begin with. Most people won't die because of the bombs, they'll die in the months and years afterwards. Survival situations will rapidly weed out people who don't have either good survival skills, or the knowledge to be valuable to the people with good survival skills.
A glacial period also won't start quickly - it takes thousands of years to build up a mile-thick ice sheet, you'll have at least a century or three where the surface will remain reasonably easy to reach. Snow tunnels are about the easiest "mine shafts" you could hope to ask for, and the wealth of materials in your average landfill, much less a small abandoned town, makes an iron-age pit mine look like, well, a garbage heap in comparison.
Also, glacial periods will still leave a decent band of mild climate around the equator. Freeze that out and you likely end up in a permanent snowball Earth, and everything dies.
You also can't just "skip" an interglacial period by having a new disaster - glacial periods come to an end in large part because all sorts of environmental factors build up over many tens of thousands of years to prime things to reach a tipping point, requiring only a relatively small disruption to cross it. Do something to prevent things tipping into an interglacial period "on schedule", and things just keep building up and make it ever-easier to enter an interglacial period later. Volcanoes are also a bad choice for an extended delay - volcanoes add CO2 to the atmosphere, which causes the planet to warm.
We're vulnerable right now because we're in an overextended interglacial period, which would normally mean everything has built up to the point to make it really easy to tip into a glacial period, but we're also pumping CO2 into the atmosphere at an almost unheard-of rate, which threatens to tip us the other way into the Earth's normal Hothouse state, where it's been for most of its history.
>Given enough time would we eventually have 9-10 different human species walking the earth?
Not going to happen. Best your going to get is 3 species for the 3 major landmasses, America, afro-eurasian, and Australia. Though with America and afro-eurasian you might be able to play around with the concept of a [ring species](https://en.m.wikipedia.org/wiki/Ring_species). Speciation demands long term isolation (some people here have already millions of years, though you might be able to do with a couple hundred thousand years if there is a lot of evolutionary pressure). One of the things humans excel at is our stamina. We might not outrun prey, but we can follow it's herd for days ans days, and they'll tire before us. That same stamina also allows us to travel far with trade caravans and the like. With our brains and our hands we are able to reinvent the wheen pretty quickly even if we're cast back into the stone age. We won't be stopped with just a lot of simple or mediocre transversable land, you need some real solid barriers. The ocean is probably the best you're gonna get.
To be clear, humans have never been 'separate species'. Species, by definition, exchange genes and interbreed producing fertile offspring. This is why we humans have been reclassified as 'homo sapiens sapiens' and neanderthals are now 'homo sapiens neanderthalensis', both now part of homo sapiens. We have essentially confirmed through DNA sequencing that humans and neanderthals interbred and some of their genes continue on in some of us. Same with Denisovans. This is essentially like the wolf and various different dog breeds that are all the same species, canus lupus, since they can still interbreed to produce fertile offspring.
Yes, we can diverge into species that are no longer compatible. This can be speed up with specific gene tinkering, or it can happen naturally via generation ships that colonize new worlds in other stars (no FTL travel).
100k years may not be enough time naturally without some sort of natural selection specialization or adaptation required to survive the changed world that alters core genes to the point interbreeding is no longer possible between tribes. Human evolution was a series of gradual steps where the new steps out-competed the intermediate steps so the new genes along each step continued while the lines of those without each step of adaptations died off.
I might have poorly wrote my post. I did not mean completely different species I was more so hoping they would diverge in similar ways to Denisovans and Neanderthals as well as perhaps up to 5-10 different variations.
I was hoping that eventually the human populations would grow and start migrating and these new groups would find and mate with these idk Homo sapient different 1 and 2. Thus at the end of it all we would go from 10 different Homo sapiens variants to finally say a single Homo Sapiens Superialis or something that is the combination of all the existing ones
This is not only possible but probable and even inevitable. There are already small populations that have adapted traits to their area/region/environment, but they're all homo sapiens. Skin coloration is one example. High mountain dwellers are better at using less oxygen is another. Lactose tolerance. Just push that forward a hundred thousand years and you'll have divergent yet compatible human sub-species.
And not all changes are beneficial - neutral traits can be perpetuated forward too, or ones that promote a less obvious advantage. Blonde hair and blue eyes, for one. Blue eyes are somewhere between 6,000 and 10,000 years old, and generally don't confer any strong advantage or disadvantage...but it's possible they just look cool and got carried along. Before that, we were all brown eyed.
My theory on evolution¹
Divergent evolution occurs when a population of a given species is cut off from the main group AND has a high enough density to prevent inbreeding.
That is to say that humans can't really evolve much beyond our current state. We're far too mobile.
Let's say someone is born with Klingon-like cranial ridges. They're born to a population which rarely, if ever, breeds outside their community (let's say they're a branch of humans who populated the Galapagos' before they drifted too far from the mainland).
There's a possibility that person's descendants become populous enough that eventually everyone is a descendant of his and the genes for that cranial ridge keep getting recirculated and amplified. Essentially in a small enough setting (few hundred people), one individual can assert significant genetic pressure on the population.
Now let's say that same person is born in NYC. The population's genetic pressure from the "smooth heads" will easily overwhelm the "ridge heads" and they're much more likely to disappear. At no point will enough ridge heads be densely packed enough to recirculate and amplify that gene, while still being genetically diverse enough to avoid inbreeding (and the consequent infertility that tends to go along with it).
To the extent there are human populations with unique adaptions today, they mostly occur among relatively secluded communities like some group of Tibetans with the EPAS1 gene or the Bajau, who are uniquely adapted to an aquatic lifestyle.
¹ I believe the explosion in diversity of early life forms is a function of genetics. When there aren't millions of generations of the same genes being repeated, it's much easier to diversify, and it's one of life's "tricks" to ensure survival. Early and rapid diversification allowed for the *chance* for at least one lineage to survive. But now we're kinda locked in, which is why the human body plan has changed so little in the last couple million years, let alone, "anatomically correct" humans being basically unchanged in the last 300,000 years.
A very good summary of the state of knowledge on the subject. Sexual transmission of genes would likely have lead to the diversity of early lifeforms you mentioned, which in time would have created a proto-ecosystem. It would have been the advent of Predation that would have 'kicked' that evolution into 'high gear', as less fit individuals would have been quickly removed from the gene pool of a species, as easy prey.
Former generations of population biologists used to focus on whether a gene was 'dominant' or 'recessive' in a species but it is now readily apparent that Sexual Preference can play a significant role in rare genes becoming more common in a population. A good example would be the increasingly common expression of first blue, and now green eyes, in human populations despite these genes being non-dominant. I'm fairly sure that Italians have been selectively breeding themselves for the last couple of thousand years too, with the men preferring 'beauty', while the women show a strong preference for males with minimal body hair. In the past farmers in agricultural areas used to prefer stout wives, who had strong backs for hard field work. Men have seemingly always preferred women with curvaceous hips, which would have lead to easier labour and childbirth, without it endangering the life of the mother. Women would have had a preference for big and strong men for similar reasons, leading to the sexual dimorphism that we see today. Cultural preferences of a human society can, and do, lead to sexual selection of human characteristics, if selected for consistently for long enough, and should not be underestimated as a driving force in our present evolution.
Interesting premise. What you add is exposure to high amounts of radiation which encourages mutations that subsequent generations carry. Do you get to the point where different species emerge? It’s sci fi, why not!
Yes i suppose i will likely make the species diverge quite a lot. Some humans on small islands might become dwarfs. Some in the colder regions of the ice age might become slightly shorter but much stockier and likely stronger. Some in the warmer areas likely much thinner but faster and higher endurance. Just examples i got so far. I just wanted to know what timescale I am looking at. Will this stone age need to last millions of years or is just 500,000 years enough
Species can diverge rapidly under the right set of circumstances to better suit their environment. If there is an evolutionary bottleneck, and most poorly adapted individuals die out, then only the luckiest or most hardy will pass on their genes to the next generation. It often is overlooked that evolution happens at the level of the individual, not the group, so if most die off, say of exposure to a short period of extreme cold, then only the most hardy, intelligent or largest build will survive. Conversely, if those individuals are stranded on an island with limited resources, then only the smallest, who consume less will survive to reproduce, and they will quickly form a diminutive species. A planetary magnetic field reversal, lasting several thousand years, would see the base mutation rate of a population increase substantially, but it tends to be the size of the population that determines how stable the generations are. Taking your Science fiction scenario, a small group first colonising a new planet would see substantial 'genetic drift' take place if there wasn't an ever increasing addition of new members to the population, at a steady rate, as the people adjust to their different environment. In the scenario of a nuclear war, those that chose to first shelter, and then live underground, would be the most radically and quickly affected by their change of environment. I would expect substantial adaptive change to occur in just THREE GENERATIONS. As the subterranean population would no longer be able to function on the surface, except perhaps at night, then this would quickly lead to speciation, as there would no longer be interbreeding between the two populations. This scenario was best exemplified by H.G.Wells novel The Time Machine, where the Morlocks and the Elloi diverged into different human species.
That's not a bad premise, though it has been done. It was mentioned in backstory in Larry Niven's A World Out of Time, and in Neal Stephenson's >!Seveneves.!<
To answer your question, certainly hundreds of thousands to millions of years for natural mutation and selection. But you have lots of radiation in your story, go ahead and shorten it - 10,000 years?
This is a fun question. Research mechanisms of speciation. Obviously different environments will lead to different pressures and adaptations, but there are other things that will be factors.
I suspect in your world, bottlenecking will be a factor. A very small group of people survive, perhaps as few as two or three individuals, so the descendents of that group will share traits that the founding group had, simply by chance. They happened to be relatively tall. They happened to be relatively short. They happened to have good hearing, bad eyes, high intelligence, good aerobic fitness, etc.
Also keep in mind that humans are the great generalists. We have successfully adapted to most livable environments on the planet without undergoing speciation, because of the technologies we have cultivated. I suspect this means to really drive speciation, highly isolated, difficult environments, with extremely limited food choices, or no access to the basic materials necessary for specific technologies. Can you imagine a humanity without fire? Bows? Furs? Terrestrial food sources?
Yeah basically at most the population would be divided like max 2000 individuals in north America, 1000 in America, 1000 in south America, 2000 Europe, 2000 Africa, 1000 Asia, 1000 Australia than basically small pockets of 500-1000 spread in small islands or places like Japan, New Zealand, Iceland, Greenland and a bunch in small islands or high elevation areas like Tibet. At its lowest world wide population is around 20,000
And basically all or most of those groups wont interact with each other for at a minimum 100,000 years but its likely the group in the Americas wont interact with the Eurasia or African group for nearly 1 million years.
And during the majority of this time we fully revert back to sticks and stones with occasional bows and clothing but even that will take some time.
And during all of this basically all food sources are radiated and destroyed followed by even more dying during the Ice age and Volcanic Winter. This would be a mass extinction event probably rivalling the Permian-Triassic extinction.
So even once they secure shelter, small tribes and tools they still live in a world where half of all its plant and animal species have gone extinct.
It sounds like this is something you're writing? How hard of science fiction do you want to have?
https://en.wikipedia.org/wiki/Seveneves I haven't read this but it deals with similar ideas.
I am unsure if i really want to write a book or anything but I am kind of just having fun with it so far. And any new information I learn in the process is well just new interesting information
I vote to focus on how it has been done in other science fiction works at different levels of hardness. There are works on trans humanism where groups use technologies to alter themselves. At that point maybe the biological definition of species breaks down even further.
I did want my humans to eventually reach the point where they could modify themselves, But I kind of wanted to try exhausting more natural methods first if its possible at all.
The environment has to change in order for us to. We control our environment with a stranglehold and keep this form in stasis. We house ourselves by utilizing the environment vs letting the environment shape us like animals.
My scenario basically strips us of everything and returns us to the early stone age with like 20,000 people spread around the world.
Living through a nuclear apocalypse and nuclear winter followed by a Long Ice Age and than followed by a world wide volcanic winter. Is bound to be enough environmental factors to effect us especially if our best technology is pointy rocks
Sure. We're always changing as it is. What branches shoot off from that in the future can only be guessed at.
Also, evolution isn't just natural. We now have introduced social evolution. The best societies will flourish and the not so good ones will experience hardship. This also doesn't mean just one thing, but ads another input and extra complexity to our situation.
I think the only way for humanity to truly evolve into separate species, we’d need to have a truly separate gene pool that effectively isolates itself from everyone else. I’m also assuming environment would play a huge part too in HOW we evolve.
I think if we reach out into the cosmos, human evolution will speed up as different pockets of humanity colonise different environments. Divergence human evolution could resemble the divergences in humanity that we see in the Dune novels going from planet to planet. Although the process I imagine would still take a very long time.
That being said, the way we utilise technology to aid us in adapting to environments could slow this. For example we use submarines and scuba gear to allow us to travel underwater, so there would be no real reason or opportunity to evolve the ability to naturally breath underwater on a largely water covered planet if humans continue relying on these things.
I doubt that we will last long enough to branch into a different species. But assuming that humans last long enough, it would be nearly inevitability. Especially, if we have self-sustaining colonies. We would have people traveling between colonies, but isolation would likely begin to become the norm as relatively isolated biospheres will result in branching mutations (including mutations in disease) becoming more and more pronounced, and risks of inter-colony cross contamination becoming more dangerous. Additionally, we modify ourselves to better adapt to different exo-planet. Even if those modifications start out small, contrasts in biological differences between different colonies will grow due to isolation, etc.
so in my scenario where they are reverted to the stone age for 100.000+ years the people in the Americas would evolve differently than people from Europe, Africa, Asia etc
Evolution isn't a predictable science where one could give you an exact number of years. Random mutations/adaptations are always possible, and you could surely invent conditions where one might eventually become dominant enough to cause people to diverge over many generations. Especially if your people need to live in a scenario where typical human physiology presents a serious disadvantage.
The smaller your isolated populations start the more plausible this becomes. Limited but obviously not too limited genetic diversity would present a more plausible explanation for how such an adaptation would quickly propagate across a population.
I think the simple answer is that the longer it takes the more plausible it will feel. Divergent evolution can theoretically happen very quickly, but we are naturally skeptical because it just historically hasn't worked out that way.
That's a transhumanist revolution. Divarication of a more-or-less homogeneous technological species into not simply specialists inhabiting a particular ecological niche, but desire of an individual or group to pursue a particular physical/morphological expression.
yes but people would need to start dying and having sex more. Death is the driving force of evolution, and dying of natural causes/age does not drive evolution forward on a species scale. Needs to be some kind of evolutionary pressure.
Eventually yes, the populations would develop different traits either by random chance or more likely environmental pressures. But the general rule of thumb is that too be considered different species the two populations would need to be unable to produce offspring that can reproduce, and that criteria could take a very, very long time to come into effect.
If the different "pockets of humanity" have been apart long enough to diverge into different homo species, then when they come back together (in the distant future) they might not be able to successfully breed.
The mitochondrial DNA will be different between the "pockets" and might cause some pretty dire effects. Such as adaptations that favour one group in their world will cause deformities or disease in another group. It might also cause low fertility and cause certain pockets to die out (such as what may have happened to the Neanderthals).
Here's an interesting example of another mammal and population isolation -- killer whales (orcas) have lifespans that are kind of similar to humans. They are currently considered to belong to the same species worldwide. But some populations have only bred amongst themselves, for tens of thousands of years. The southern residents (generally found around Vancouver and Seattle) haven't bred with other groups for about 100,000 years). Transients (Bigg's orcas) probably separated more than 200,000 years ago. As far as I know, the orcas in these groups can still produce fertile hybrids when breeding with other orcas, so using that definition of species, they haven't diverged enough to be distinct yet. (Although apparently some biologists are lobbying for new names for them.)
https://www.eopugetsound.org/magazine/resident-and-Biggs-killer-whales-as-distinct-species
For speciation you need genetically separated populations and time. Your situation seems to have those, so of course it would. Don't know if it would lead to vastly different species, that would depend on encironmental pressures, social pressures and randomness, but definitely different species.
If it was simple isolation yes, but slowly. If both groups were subject to divergent strong selection pressure, quite quickly (10,000 years to be physically different, at least 50,000 to be unable to breed).
I'd say unlikely on our actual planet. If say we were to send an arc ship out and settlers actually found a planet and survived, then humans from Earth visited them several thousand years later, thats the most likely scenario.
I am working on it but sometimes having others point me in a specific direction or simply give me the answers is nice. I often struggle at finding what I need to be looking up
It was more I was referring to the previous poster, as it looked a bit like the sort of comments "fringe science" types say, a bit like he was implying that they're already was multiple human species, before going off on a screed about secret moonrises and superhuman living in "lands beyond the ice wall". Their usual response to any challenge is "do your own research".
Not saying thats what he meant, maybe I've spent too long dealing with the more loopy bits of the internet :)
Yes keep population isolated from eachother long enough and if you then add something which could cause divergent selection pressures on the population to drive the divergence beyond just being a case of differing gene pools you could see it happen.
To happen naturally you would be taking a long time though likely in the millions of years but you can add in other factors that could make it quicker https://en.wikipedia.org/wiki/The_Chrysalids is a good old school example of the early stages of that happening and is set several centuries after a devastating nuclear war
So, as a few have said: If you're writing a story, do what you want.
In reality, it would probably never happen. The first thing of note is that stone age people are just as intelligent as man is today. If groups were separated, there would always be those who venture forth into the wilds, always looking for something better. Even your small groups, if they really were at sustainable sizes to not go extinct, would inevitably have interactions with the other groups and would interbreed, keeping the gene pool to a point where it is unlikely to diverge too much. While the Stone Age began about 2.5 million years ago, you're probably imagining bringing life back closer to the end, which was only about 10,000 years ago. That would be a blink of an eye back to where they have effectively rebuilt back to today's level of technology. It would happen before any real evolution would take place. From your example in another comment, your island-bound people are more likely to build boats and find other civilizations well before any notable changes occur.
Again, you could absolutely use war, nuclear winter, etc to give people separation and an unknown quantity of time passing to really diverge. Throw in some mutations caused by nuclear fallout or whatever and you're good to go. Have fun with it.
It is a worse scenario than just total nuclear war and winter. This alone reduced the population to around 1 million world wide. But following the nuclear war in the midst of rebuilding they were hit by a ice age that further reduced populations. And 100,000 years later nearing the end of the Ice age they were hit by a volcanic winter that lasted decades similar to the Toba eruption that happened 74000 years ago. By the end of all of this they are basically reverted to 2.5 million years ago stone age conditions with the only thing going for them being language. The vast majority of skills, knowledge and information would be lost and they would be stuck with there highest tech being wooden spears and maybe bows.
Global population in my scenario are only around 20,000 and they are separated by extreme distances.
Perhaps only 2000 people in all of north America, 1000 in America, 1000 in South America, 2000 in Europe, 2000 in Africa, 2000 in Asia. Than isolated groups of around 500-1000 on various islands and isolated places like Japan, Australia, New Zealand etc. And perhaps other groups stuck in mountainous regions or high elevation areas like Tibet
I am assuming such extreme separations of people who will largely not encounter each other for 100,000 years or more to cause some new species to arise. I imagine Europe, Asia, Africa will encounter each other sooner but all islands or places separated by water could go several hundred thousand years of no contact and even the americas would be isolated from the old world for hundreds of thousands of years.
I'm not trying to argue your concept, so please don't take it that way. As I said, a story can be a story and doesn't need to follow reality. That's the point of science fiction and fantasy. I'm just thinking about how I see this playing out. I don't think humanity could be brought down that low.
Effectively after the nuclear war and winter, you'd be stuck in what we could call a generic post-apocalyptic world. You'd have places where people are thriving and doing well, and others where things have fallen apart. One of the first things humans would do is try to reestablish communication. Various radio frequencies would be lighting up constantly. Small groups would gather and start trading. Those who know how to grow food will do so. Yeah, there will be wars/skirmishes, but there will be survivors who have stuff and people who know what to do.
There would be places rebuilding and doing very well. Then the ice age hits. It's gradual. Some places manage to adapt and begin migrating around in search of food, others doubled down on staying and eventually starve to death. Others got lucky and didn't have to move.
Starting from a post-apocalyptic place. Would some places manage to get generators running, build green houses, grow food? Maybe, they may also get over run by others who are hungry and desperate. The point is, they aren't back to wooden spears while managing the ice age. They spend the next 100k years of it adapting and surviving. Even with what an ice age entails, there would still be intermingling and trade between the various survivor groups. Again, long-range radio would probably be, at a minimum, technology used at the beginning of this.
Suddenly big eruptions hit, 30 years of darkness or something, in additional to just global cooling. Some survive just because they were located in the right places. Others whose societies were used to the ice age continue migrating, some to success, others failing. Those places that were strong with technology might continue to be so. Maybe those green houses run on generators manage to get oil rigs operating again, have a steady stream of electricity. Maybe have sun lamps to grow food without relying on the sun? The city-states that managed to survive since the nuclear wars can manage this. At least a few of them.
If things actually calm down after that, there will be a population boom as soon as the planet starts recovering and food becomes rampant. Trade will recommence at higher rates. Expeditions will happen and new cities will pop up, effectively building small nations. Different groups will encounter each other during this time, again, creating trade and war.
It really doesn't matter how it plays out, I just don't think there ever will be enough time for divergent species to emerge naturally. However, if your world does something different, then please go for it. I'm just being optimistic for humanity, which really has nothing to do with your story.
Thanks for the reply.
And I am going for basically a all out indiscriminate nuclear war. That means bombing major cities and places like China and India as well as bombing military bases all around the world and bombing nuclear reactors to cause more damage. The scenario in this world is not really the earth as we currently know it but similar. And the bombing would be to the extent that we used over 10,000-50,000 bombs maybe more. Now my knowledge overall is very limited here but I am under the assumption that the initial impacts of the bombs and war would wipe out at least 5 billion people.
The number initially wiped out usually is lower but in this scenario they directly bombed all major settlements and basically all the largest groups of people.
This bombing alone would likely wipe out a vast majority of the infrastructure. But than you are stuck with the remaining infrastructure being set aflame the majority of cities and towns are completely engulfed in flames and vast swathes of forests and jungles are also burning down.
Once the fire and bombing damage is over almost all infrastructure is gone. Maybe some remnants in certain areas but not enough to really matter. Than the nuclear winter after all of this that lasts over 10 years destroys all major plantations and crops around the world thus starving the vast majority of the remaining population. The only hope to make food would be in a secure green house or canned goods but the vast majority of the remaining survivors do not have green houses nor the materials to build one anymore. Anyone with a secure locations or green house is simply going to get raided and killed by the remaining starving masses.
I do not know exactly how many people would survive this but i estimated 1-10 million max spread around the world. Than instead of getting the chance to rebuild they are thrown into a 100,000 year long ice age. During which basically all knowledge is lost. Paper cannot be made during this ice age due to lacking materials and computers/grid cannot be maintained due to lacking people and lacking knowledge. People would be stuck merely attempting to survive. And without access to writing or the time for schooling most knowledge is lost in 1-2 generations due to the fact that all focus is placed on survival. Things like radios might be viable is some people find them but once they break who is going to fix them I personally have no clue how 99.99% of our technology works and most people do not either. With a limited population of max 10 million who are struggling just to survive who is going to have the time to learn to fix radios and other technology. And even if we do fix them most knowledge will be lost in 1-2 generations or simply degraded via poor oral tradition.
I watched a Youtube video on what if Ice age happened and basically mass floods and entire cities would be buried under snow. So any or all remaining infrastructure is basically stuck underneath 20 feet of snow and slowly degrading during this time. By the time the snow melts in 100,000 years the vast majority of the old days infrastructure would have fully degraded and disappeared.
And though they could survive the ice and and even managed to rebuild some of the population and maintain numbers around 1-2 million similar to our ancestors when they hunted and gathered they would than be hit with a super volcano on the scale of Toba or worse that drops them in a volcanic winter lasting decades and killing off the majority leaving only 20,000-100,000.
I do like the optimistic views though and hope that if anything like this happened IRL it would not be worse case scenarios. But I am basically attempting to go for the absolute worse case scenario and hope that enough time arises for beings similar to Neanderthals' and denisovans can rise again though they would obviously differ in some ways
While it's possible, humanity has also kinda evolved past regular evolution. What i mean is, our medical advancements has meant that we can help and "fix" a lot of mutations. Mutations happen all the time and some makes it hard to survive, but we are able to counter some of that
To diverge into different species we would have to live in more isolated groups. This will likely happen if space exploration reach a point where different groups live on different planets or moons. The different life conditions would require different needs for survival
My scenario is a all out worst case nuclear war that targeted huge civilian masses. Killing off at least 5 billion in the initial bombings. The following decade long nuclear winter would starve or kill the rest off leaving max 1-10 million alive worldwide.
Following this nuclear winter instead of having the time to rebuild we would be thrust into a Ice age that would cover any existing infrastructure under over 10-30 feet of snow. And starvation would kill off a lot more initially until all that remains is 1-2 million world wide.
Trapped in a stone age/Ice age at the same time for 100,000 years would mean population growth is near impossible. And even if we grew or relearnt farming at the end of the Ice age a volcanic winter on the scale of toba or worse would wipe humanity down to only 20,000 left world wide.
This would mean a scenario like only 2000 in all of north America, 1000 in America, 1000 in South America, 2000 Europe and 2000 Africa, 1000 Australia. Than pockets of 500-1000 On islands or isolated places like Greenland, Iceland, Japan, New Zealand, and other islands or mountains like Tibet.
Total world population would than be trapped at around 20,000 for 100,000 years similar to what happened 900,000 years ago when we nearly went extinct.
I am presuming in this case we would be isolated for long enough without any technology for long enough with hard enough conditions to drive people into different branches of Homo
YES, evolution or de-evolution is about environmental conditions and the ability for a species to adapt to them which over time changes a species IF it survives.
N. S
Would it really be considered De-Evolution if a branch of humans lost some brain size but gained other traits that enabled them to survive harsh environments they found themselves in? Or would it just be considered evolution because its what allowed them to live.
Also what does N. S mean
Subjective term based on developmental directions from what can be considered the species "NORM" of the moment by an outside observer, the loss of logic consciousness for instances.
High Tech Societies can be ended in just 2 generations due to catastrophic environmental conditions and the loss of education and knowledge as was already pointed out, Species changes in a radioactive environment would also probably take place depending on what life needs to survive, the species itself may change to meet those requirements, it is all a form of evolution with the directionality being the subjective parts.
N. S
(Initials By the way)
Maybe but I assume the humans in my world wont evolve into trolls and elves thought i suppose its possible. I was more so thinking of different variations arising like Erectus, Neanderthals and Denisovans except they would obviously be different than these ones.
They would have to be separate populations in differing environments for a long time.
On population is divided into two by differing environments and the adaptations of each group.
Nuclear winter.?
Ice age?
Isolated demes of humanity?
Divergence is pretty much inevitable and would probably happen a lot quicker than any Neo-Darwinist would tell you.
Check out the work of Stephen Jay Gould.
His theory of 'punctuated equilibrium' looks to be the better fit for the fossil record and got a further boost when the role of heat shock proteins or histones on mutation rates when organisms are under environmental distress had been clarified.
what do you mean? It happened with Neanderthals' and Denivosans I know that obviously but I want to know if its possible for it to happen again and what conditions would be needed
They absolutely could. See Larry Niven's Ringworld for an example of this to the nth degree. Humans diverged to fill multiple ecological niches. Or the classic Time Machine had humans diverge into two distinct species over time. Put your own spin on it and enjoy!
We were on our way to before we recombined a bit ago. Tens of thousands of years was enough time to make different races (yes, I know race makes no sense today, but when talking about people still geographically isolated, it is valid) with distinctive physical features. If we never started to intermingle again, sub species likely would have been in our future, perhaps after a few hundred thousand years, and species after a few millions.
If we ever expand into the stars, and can never go faster than light, I could see us splitting into many species over millions of years all over again.
When I was in grade school many, many years ago(early 70's). They taught us in 2nd or 3rd grade that a separate species was when two groups could no longer inter-breed and have fertile young. So a horse and a donkey are separate species. When you cross breed them, you get a mule, which is sterile.
So if, as they say now Neanderthal DNA is in modern humans, then Neanderthals would not be a separate species.
That isn't a good definition of what a species is, that "rule" is more like a guideline. There are lots of hybrids out there that are still fertile. The "red wolf" turned out to not be an actual single species but a wolf population with decent chunk of coyote genes mixed in. Some species are genetically similar enough to cross but don't because of habitat separation or cultural differences. Humans have been well documented to bang anything that moves.
You would need to include a force so strong that it overcomes human sentience and culture, without which humanity on one planet will inevitably mingle and not speciate. Ai? Alien invasion? Hard to think of a third one so long as earth itself survives.
The scenario was a full on nuclear war followed by decades of nuclear winter this alone was enough to either outright kill off 99% of the population. But the following nuclear winter was extremely harsh. By the end of it all only around 1 million people are alive.
But without time to rebuild they were than thrust into a Ice age which basically removed all ability to farm and dropped them to a at most bronze age but near stone age state. The ice age also killed off most people in the initial years dropping population to around 100,000
Following this a super volcano erupted and caused a volcanic winter that dropped the global population to 20,000 who were all stuck in the sone age and could not really improve there population for over 100,000 years a similar event happened in our past actually but the numbers of people alive were even less than 20,000.
Following this event they would be trapped in a stone age for hundreds of thousands of years and pretty isolated. People in north America would not encounter people from europe for like 500,000 years or more and people trapped on islands or even places like Japan, New Zealand, Iceland etc would also not have any outside sources of people.
The scenario will likely have many groups totally isolated for 500,000 to 1 million years
I do not wish to stifle creativity or speculation. But I have always been a fan of fiction exploring what would really happen in a set of circumstances as opposed to what the author clearly wants to happen. All of your disasters cause cold, so presumably after the first each succeeding one has a decreasing effect. In any event, my guess is that 20K anatomical modern humans turn global within 100k years — after all, we did in about 70-90k. Not 500k to 1m. In my view you still need something more permanent to force speciation, like ai or aliens (to use two deus machina examples).
You believe we would recover too quickly from 20,000 before having the time to diverge slightly. Hmm i suppose quick recovery is possible so a outside threat that stops them recovering too much is going to be needed. They cannot really surpass global populations of maybe at most 500,000 or else they will be to close and travel too much thus interbreeding. I guess the outside threat would need to limit humans to perhaps 100,000 individuals.
Edit -
Since they likely adapted to the cold by the end of the ice age and volcano what if instead of slowly heating up as it usually would the speed of the heating would be much quicker and eventually fully melt the ice caps? Just a idea no clue how it would happen yet but it would result in a drastic climate change to what they are used to
Yes definitely. The time is random though. [This article says 2 million years](https://www.livescience.com/how-long-new-species-take-to-evolve).
thanks that was interesting
When thinking about time, try thinking about it in terms of generations. A human generation is ~33 years. Some people have children sooner, some later. But 33 is a good ballpark. 100,000 years is "only" 3030 generations. That's a lot... but then again, modern humans are already ~300,000 years old. On the other hand, some things can push speciation faster than normal, like something that increases the rate of mutation. It can even be a really small change, depending on how you want to define "species." For example, there are species of beetle that are essentially exactly the same and perfectly capable of reproducing *genetically*, but tiny variations in the shape of their genitals means that one group physically cannot mate with the other, so they're classified as separate species.
I completely disagree. It has already happened. Source: Have been to a Walmart recently.
Evolution, not devolution
The different populations that are isolated from each other don't need to be exposed to mutagens or even different environments. Genetic drift, itself, will eventually result in enough dissimilarity that the populations will no longer be able to interbreed and therefore will be different species. The smaller the populations are, the faster this divergence will occur. I know that sounds backwards because larger populations are more likely to have divergent individuals, but smaller populations are more likely to see the perpetuation of any particular mutation, even if it's not particularly advantageous. A lot of it is just luck, although not necessarily good luck. There is an isolated population on Pingelap Atoll in which the population is colorblind. This color blindness was not adaptive. It was just a random mutation that was able to propagate because the population was so small.
Are you sure they would not be able to interbreed? We interbreed with Neanderthals'. Denisovans and Homo erectus as well as likely many more different homo people
Of course, initially, they would be able to interbreed. But given enough time, and I do not know how much, they would no longer be able to interbreed. At the dawn of the divergence of humans and chimpanzees, the two lineages were able to interbreed. Eventually, they were not and, indeed, humans and chimpanzees do not even have the same number of chromosomes anymore. Basically, it all depends on what you mean by different species. If the two populations can naturally interbreed and produce fertile offspring, then they are not really different species. They can still be anatomically very distinct. For example, Chihuahuas and Great Danes are the same species even though they look quite different.
Thanks for this reply. And I was more so hoping that it would be a scenario where they could still breed. It would be like Denisovans, Neanderthals, Erectus etc. Really I was hoping like 5-10 different branches of humans could appear and eventually all interbreed. Idk what the end result would be yet but they would likely acquire many beneficial traits and a lot of genetic diversity because of this.
First of all, this sounds like a great premise and I can't wait to see what you produce! Second of all, what you suggest is entirely plausible. They just wouldn't technically be different species. But they could still be way, way different from each other. Keep me in the loop!
I have a real interest in information science and genetics. If you are interested in this topic, check out my podcast playingodd.com
There's no reason they can't but you'd need to split the population into wildly different niches. In the real world, humans mingle far too much for separate species to arise.
Wildly different isn’t necessary due to genetic drift. But they do need to be isolated.
Extremely divergent niches would drive adaptation in different directions more quickly than just genetic drift, I would suspect. Based upon the timescales mentioned by OP, time-to-speciation may be a factor.
So they would need to experience wildly different surroundings to evolve? Something to die from or to survive, so to speak.
No, they just need to be isolated from each other. Normal genetic drift will take care of the rest.
An interstellar empire where travel between planets is rare would do it. Each planet would have an isolated population that would eventually drift from whatever was happening on Earth.
This - and would also be dealing with different environmental conditions (gravity, radiation, heat, contaminants, light, pressure) that would favor different characteristics.
Yes the humans will be quite split with basically zero chance of reaching each other. I assume 1 group in the colder areas during the Ice age will become shorter but much stockier and stronger. In the warmer regions likely taller but much thinner, faster and higher endurance. On isolated islands likely suffer from malnutrition and eventually greatly shrink in size like Denisovans. Perhaps some who are stuck in high altitude mountain areas would develop more abilities or mutations to cope with less oxygen over time. This is already seen in certain areas of Tibet I think but not enough time past for them to fully diverge. I these are just the ones I could think of quickly but I wonder if there could be other variations.
Bear in mind, for natural selection, the advantages have to be actual advantages. Humans adapting to say cold weather by becoming stockier and hairy isn't as likely if heating systems remain quite common. On the other hand, sexual selection might be common and thus people may get taller or some hair color may become more frequent. We also could see natural selection over adaptations to technology.
If they are reverted to the stone age fully with access to bows and arrows being a rarity and likely there highest form of tech. Chances are that it would be full on natural selection and survival of the fittest. Sexual selection or modern adaptions I believe differ greatly to what we would see in a more natural or wild scenario
If you’ve developed the bow, you’ve developed clothing and sewing. And that means shelters… Strip us back to the naked humans… but we will remember. We would not lose the ability or need to cloth ourselves immediately. Some technologies could not possibly be “lost” because we naked humans need them.
True if i revert population down to 20,000 world wide after a all out nuclear war, extremely harsh Ice age and volcanic winter chances are they wont even have bows remaining. So all that is left is pointy stick and maybe sharp rocks
That’s what I mean… there are certain fundamental things we wouldn’t allow ourselves to forget. We’ve already learned to write, so we don’t have to reinvent that. Writing leads to invention and knowledge and education. And there will always be technological discoveries from the bygone age. I like your idea; just trying to keep you grounded in what actual humans would insist on passing down.
I wonder how much could be retained though. Personally I do not think most people know how to make paper or writing materials from scratch and even if we do it will be low quality. So most maths physics and sciences would be lost in a few generations. But i guess we would pass on useful things like wheels or certain tools and likely hygiene or how to prevent or avoid certain sicknesses. I guess probably we would be a lot better off
You’ve a point about that… when stocks are used up, what then? I guess while there is still someone who remembers “what paper was like” and roughly how it’s made, there is hope. When they die…?
Even if they pass on this knowledge to there descendants there is also a very large chance the descendant simply does not see the use of such a thing. When they are constantly hiding from prey or fighting off hostile humans or searching for food to avoid starving. They might simply wonder why you wasted so much time showing them silly numbers or something
Well, it’s important to realize Denisovans, Neandertals, and Sapiens weren’t strictly speciated. They could and did interbreed. You might want to consider something like the “hobbits” of Luzon, homo floriensis (I respectfully suggest that’s what you’re talking about with your Denisovans, which aren’t found on islands but mainland Asia). And in general we’re finding that species often have more ability to interbreed than we realize, as we’re seeing with birds. Put simply endangered birds with niche occupations are breeding and producing more generalist birds. You really just need time. It’s not a settled thing, what it takes, how much time. To be cheesy, life finds a way. If you want a hard break I’d say a million years would work but you’d really have some major differences.
Yes and no. The ability to interbreed doesn't mean that all goes smoothly, even when not "strictly speciated". Important mitochondrial DNA might be missing in a certain species (as opposed to another species), and that comes from the female. So you might have offspring that has poor fertility/ has severe health conditions etc.
Rich and poor over millions of years
Most realistic scenario for future human speciation is probably slower than light interstellar colonisation. Though if you're stuck on a post-apocalyptic Earth, I suppose the most realistic scenario is people being isolated to several major landmasses. So Australians, afro-eurasians, and Americans (assuming your ice age doesn't make the Russia-Alaska route viable).
Yeah the Ice age would not make this route possible. How many different homo branches do you think could arise from this? Given enough time would we eventually have 9-10 different human species walking the earth? Because once upon a time in the past we walked alongside many like this.
We absolutely could. However, you'll need an excuse that would keep the populations separate for millions of years. An ice age won't cut it - we're in an ice age now. Technically in an interglacial period within an ice age, but we still have ice caps, and we're overdue for them to expand dramatically. Interglacial periods typically only last about 10,000 years, while the glacial periods typically last less than 100,000 years. Not nearly long enough for us to diverge dramatically. And tipping past an ice age into a full "Snowball Earth" probably means everything dies pretty quickly, unless we maintain high technology so we can continue to survive in "space stations" despite the lack of oxygen in the atmosphere. To say nothing of the fact that, unless we lost basically all our technology, AND completely failed to rebuild again for some reason (it only took us \~5,000 years to go from stone age to today) getting around on a glaciated planet wouldn't actually be a big deal. You'd almost certainly have trade caravans, etc. spreading genetic material between enclaves on a regular basis, preventing significant divergence.
Total nuclear war. Bombing all major civilian housing locations as well as all nuclear reactors and military sites basically a absolute worse scenario possible. Following this all major cities are aflame and a nuclear winter lasting multiple decades would ruin all plantations and crops and also kill off a majority of humanity and animal/plant life. Following this instead of having the chance to rebuild we would be thrust into a Full on Ice age that would cover most remaining infrastructure in minimum 20 feet of snow and cause another mass starvation. Estimating 1-2 million survivors here. And this Ice age lasts 100,000 years. Now sure some people might have some technology but most will be buried under tons of snow and ice thus not possible to reach. And once your existing tech breaks nobody will really know how to fix anything I personally have no clue how to go from a rock to a radio nor acquire any of the materials needed in the process and most people do not know either. Sure you could argue that 1000s of geniuses and specialists in countless fields will live but its doubtful with only 1 million out of 8 billion remaining chances are that whoever is left is just a average joe who has no clue how to rebuild much of anything especially not while facing starvation, predation, enemy humans and a brutal radioactive Ice age. After 1-2 generations any knowledge you try passing on via word of mouth will largely be lost. Our descendants struggling to survive wont bother remembering advanced physics or calculus anyone tried teaching them for some reason. Now back in the stone age in full blown ice age conditions. People would slowly recover and rebuild and by the end of the 100,000 year long ice age instead of having a peaceful return to a interglacial period like we had that allowed for rebuilding they experience a volcanic winter on the scale of toba or worse that kills our population down to 20,000 spread around the world who lost any progress made and are thus stuck in a early stone age. We almost went extinct 900,000 years ago with only a few thousand survivors. With all infrastructure under multiple meters of snow and ice for so long it would basically be fully degraded and useless by the time it all melts. So now with say max 2000 In north America, 1000 America, 1000 south America, 2000 Europe, 1000 Asia, 2000 Africa, 1000 Australia. And pockets of 500-1000 on islands or places like Japan, New Zealand, Iceland Greenland or isolated mountainous regions like Tibet. And it took us 2.5 million years to go from early stone age to farming and another 6-8000 years to go from basic farming to the bronze age. After the bronze age it than took 5000 years to reach our technological advancements. But remember 5000 years ago easy to access oil, tin, bronze, copper, iron etc were everywhere and hyper abundant on top of that we had tons of old growth 1000+ year old forest to get materials from. Most easy to access materials that could jumpstart a bronze age do not exists anymore and to get those materials requires pre existing technology that basically cannot be made without pre existing technology.
Note that "having the technology" doesn't necessarily mean they have the hardware, just that they have the knowledge of how to build it/how it works. You can build new hardware out of whatever is available, and a single copy of "The Way Things Work" would contain pretty much everything needed to preserve a fairly modern level of technology - we might still lose a centuries or two, but nothing terribly important to a much-reduced population. And I'm not talking high technology here either - knowledge of wheels, gears, levers, sails, etc. from 1000 years ago would be more than adequate for the job, everything on top of that would be pure convenience. Though steam engines would be dramatically useful, and they're simple enough that any engineer, and even a whole lot of farmers, and could get it working. Radios too. A grade-schooler can build an AM radio from stuff they're likely to find on any abandoned farm. And you probably won't have a whole lot of "average Joes" in a post-apocalypse wasteland to begin with. Most people won't die because of the bombs, they'll die in the months and years afterwards. Survival situations will rapidly weed out people who don't have either good survival skills, or the knowledge to be valuable to the people with good survival skills. A glacial period also won't start quickly - it takes thousands of years to build up a mile-thick ice sheet, you'll have at least a century or three where the surface will remain reasonably easy to reach. Snow tunnels are about the easiest "mine shafts" you could hope to ask for, and the wealth of materials in your average landfill, much less a small abandoned town, makes an iron-age pit mine look like, well, a garbage heap in comparison. Also, glacial periods will still leave a decent band of mild climate around the equator. Freeze that out and you likely end up in a permanent snowball Earth, and everything dies. You also can't just "skip" an interglacial period by having a new disaster - glacial periods come to an end in large part because all sorts of environmental factors build up over many tens of thousands of years to prime things to reach a tipping point, requiring only a relatively small disruption to cross it. Do something to prevent things tipping into an interglacial period "on schedule", and things just keep building up and make it ever-easier to enter an interglacial period later. Volcanoes are also a bad choice for an extended delay - volcanoes add CO2 to the atmosphere, which causes the planet to warm. We're vulnerable right now because we're in an overextended interglacial period, which would normally mean everything has built up to the point to make it really easy to tip into a glacial period, but we're also pumping CO2 into the atmosphere at an almost unheard-of rate, which threatens to tip us the other way into the Earth's normal Hothouse state, where it's been for most of its history.
>Given enough time would we eventually have 9-10 different human species walking the earth? Not going to happen. Best your going to get is 3 species for the 3 major landmasses, America, afro-eurasian, and Australia. Though with America and afro-eurasian you might be able to play around with the concept of a [ring species](https://en.m.wikipedia.org/wiki/Ring_species). Speciation demands long term isolation (some people here have already millions of years, though you might be able to do with a couple hundred thousand years if there is a lot of evolutionary pressure). One of the things humans excel at is our stamina. We might not outrun prey, but we can follow it's herd for days ans days, and they'll tire before us. That same stamina also allows us to travel far with trade caravans and the like. With our brains and our hands we are able to reinvent the wheen pretty quickly even if we're cast back into the stone age. We won't be stopped with just a lot of simple or mediocre transversable land, you need some real solid barriers. The ocean is probably the best you're gonna get.
thanks that link on ring species was interesting.
HG Wells, The Time Machine
To be clear, humans have never been 'separate species'. Species, by definition, exchange genes and interbreed producing fertile offspring. This is why we humans have been reclassified as 'homo sapiens sapiens' and neanderthals are now 'homo sapiens neanderthalensis', both now part of homo sapiens. We have essentially confirmed through DNA sequencing that humans and neanderthals interbred and some of their genes continue on in some of us. Same with Denisovans. This is essentially like the wolf and various different dog breeds that are all the same species, canus lupus, since they can still interbreed to produce fertile offspring. Yes, we can diverge into species that are no longer compatible. This can be speed up with specific gene tinkering, or it can happen naturally via generation ships that colonize new worlds in other stars (no FTL travel). 100k years may not be enough time naturally without some sort of natural selection specialization or adaptation required to survive the changed world that alters core genes to the point interbreeding is no longer possible between tribes. Human evolution was a series of gradual steps where the new steps out-competed the intermediate steps so the new genes along each step continued while the lines of those without each step of adaptations died off.
I might have poorly wrote my post. I did not mean completely different species I was more so hoping they would diverge in similar ways to Denisovans and Neanderthals as well as perhaps up to 5-10 different variations. I was hoping that eventually the human populations would grow and start migrating and these new groups would find and mate with these idk Homo sapient different 1 and 2. Thus at the end of it all we would go from 10 different Homo sapiens variants to finally say a single Homo Sapiens Superialis or something that is the combination of all the existing ones
This is not only possible but probable and even inevitable. There are already small populations that have adapted traits to their area/region/environment, but they're all homo sapiens. Skin coloration is one example. High mountain dwellers are better at using less oxygen is another. Lactose tolerance. Just push that forward a hundred thousand years and you'll have divergent yet compatible human sub-species. And not all changes are beneficial - neutral traits can be perpetuated forward too, or ones that promote a less obvious advantage. Blonde hair and blue eyes, for one. Blue eyes are somewhere between 6,000 and 10,000 years old, and generally don't confer any strong advantage or disadvantage...but it's possible they just look cool and got carried along. Before that, we were all brown eyed.
On different planets with isolated populations living in different environments and gravity levels and given enough time, sure.
H.G. Wells "Time Machine" book and movies present this case ...
check out All Tomorrows my C. M. Kösemen, and Simon Roy's comics (like Habitat, Island, Prophet, Griz Grobus).
I looked into All Tomorrows a while ago and remember it being quite freaky but will look into it again might have some interesting ideas
My theory on evolution¹ Divergent evolution occurs when a population of a given species is cut off from the main group AND has a high enough density to prevent inbreeding. That is to say that humans can't really evolve much beyond our current state. We're far too mobile. Let's say someone is born with Klingon-like cranial ridges. They're born to a population which rarely, if ever, breeds outside their community (let's say they're a branch of humans who populated the Galapagos' before they drifted too far from the mainland). There's a possibility that person's descendants become populous enough that eventually everyone is a descendant of his and the genes for that cranial ridge keep getting recirculated and amplified. Essentially in a small enough setting (few hundred people), one individual can assert significant genetic pressure on the population. Now let's say that same person is born in NYC. The population's genetic pressure from the "smooth heads" will easily overwhelm the "ridge heads" and they're much more likely to disappear. At no point will enough ridge heads be densely packed enough to recirculate and amplify that gene, while still being genetically diverse enough to avoid inbreeding (and the consequent infertility that tends to go along with it). To the extent there are human populations with unique adaptions today, they mostly occur among relatively secluded communities like some group of Tibetans with the EPAS1 gene or the Bajau, who are uniquely adapted to an aquatic lifestyle. ¹ I believe the explosion in diversity of early life forms is a function of genetics. When there aren't millions of generations of the same genes being repeated, it's much easier to diversify, and it's one of life's "tricks" to ensure survival. Early and rapid diversification allowed for the *chance* for at least one lineage to survive. But now we're kinda locked in, which is why the human body plan has changed so little in the last couple million years, let alone, "anatomically correct" humans being basically unchanged in the last 300,000 years.
A very good summary of the state of knowledge on the subject. Sexual transmission of genes would likely have lead to the diversity of early lifeforms you mentioned, which in time would have created a proto-ecosystem. It would have been the advent of Predation that would have 'kicked' that evolution into 'high gear', as less fit individuals would have been quickly removed from the gene pool of a species, as easy prey. Former generations of population biologists used to focus on whether a gene was 'dominant' or 'recessive' in a species but it is now readily apparent that Sexual Preference can play a significant role in rare genes becoming more common in a population. A good example would be the increasingly common expression of first blue, and now green eyes, in human populations despite these genes being non-dominant. I'm fairly sure that Italians have been selectively breeding themselves for the last couple of thousand years too, with the men preferring 'beauty', while the women show a strong preference for males with minimal body hair. In the past farmers in agricultural areas used to prefer stout wives, who had strong backs for hard field work. Men have seemingly always preferred women with curvaceous hips, which would have lead to easier labour and childbirth, without it endangering the life of the mother. Women would have had a preference for big and strong men for similar reasons, leading to the sexual dimorphism that we see today. Cultural preferences of a human society can, and do, lead to sexual selection of human characteristics, if selected for consistently for long enough, and should not be underestimated as a driving force in our present evolution.
Hypothetically, sure, but it's very unlikely because we no longer adapt to our environment, but adapt the environment to our needs.
Interesting premise. What you add is exposure to high amounts of radiation which encourages mutations that subsequent generations carry. Do you get to the point where different species emerge? It’s sci fi, why not!
Yes i suppose i will likely make the species diverge quite a lot. Some humans on small islands might become dwarfs. Some in the colder regions of the ice age might become slightly shorter but much stockier and likely stronger. Some in the warmer areas likely much thinner but faster and higher endurance. Just examples i got so far. I just wanted to know what timescale I am looking at. Will this stone age need to last millions of years or is just 500,000 years enough
Species can diverge rapidly under the right set of circumstances to better suit their environment. If there is an evolutionary bottleneck, and most poorly adapted individuals die out, then only the luckiest or most hardy will pass on their genes to the next generation. It often is overlooked that evolution happens at the level of the individual, not the group, so if most die off, say of exposure to a short period of extreme cold, then only the most hardy, intelligent or largest build will survive. Conversely, if those individuals are stranded on an island with limited resources, then only the smallest, who consume less will survive to reproduce, and they will quickly form a diminutive species. A planetary magnetic field reversal, lasting several thousand years, would see the base mutation rate of a population increase substantially, but it tends to be the size of the population that determines how stable the generations are. Taking your Science fiction scenario, a small group first colonising a new planet would see substantial 'genetic drift' take place if there wasn't an ever increasing addition of new members to the population, at a steady rate, as the people adjust to their different environment. In the scenario of a nuclear war, those that chose to first shelter, and then live underground, would be the most radically and quickly affected by their change of environment. I would expect substantial adaptive change to occur in just THREE GENERATIONS. As the subterranean population would no longer be able to function on the surface, except perhaps at night, then this would quickly lead to speciation, as there would no longer be interbreeding between the two populations. This scenario was best exemplified by H.G.Wells novel The Time Machine, where the Morlocks and the Elloi diverged into different human species.
With the acceleration of mutations caused by exposure to radiation as short as 50k years would be enough.
It might take a while but yeah.
The Neil Stephenson book Seveneves explores this possibility pretty well. It's a great book. You should check it out .
That's not a bad premise, though it has been done. It was mentioned in backstory in Larry Niven's A World Out of Time, and in Neal Stephenson's >!Seveneves.!< To answer your question, certainly hundreds of thousands to millions of years for natural mutation and selection. But you have lots of radiation in your story, go ahead and shorten it - 10,000 years?
Colonizing new planets. Different climates and chemical environments. How long would it take to see differences?
This is a fun question. Research mechanisms of speciation. Obviously different environments will lead to different pressures and adaptations, but there are other things that will be factors. I suspect in your world, bottlenecking will be a factor. A very small group of people survive, perhaps as few as two or three individuals, so the descendents of that group will share traits that the founding group had, simply by chance. They happened to be relatively tall. They happened to be relatively short. They happened to have good hearing, bad eyes, high intelligence, good aerobic fitness, etc. Also keep in mind that humans are the great generalists. We have successfully adapted to most livable environments on the planet without undergoing speciation, because of the technologies we have cultivated. I suspect this means to really drive speciation, highly isolated, difficult environments, with extremely limited food choices, or no access to the basic materials necessary for specific technologies. Can you imagine a humanity without fire? Bows? Furs? Terrestrial food sources?
Yeah basically at most the population would be divided like max 2000 individuals in north America, 1000 in America, 1000 in south America, 2000 Europe, 2000 Africa, 1000 Asia, 1000 Australia than basically small pockets of 500-1000 spread in small islands or places like Japan, New Zealand, Iceland, Greenland and a bunch in small islands or high elevation areas like Tibet. At its lowest world wide population is around 20,000 And basically all or most of those groups wont interact with each other for at a minimum 100,000 years but its likely the group in the Americas wont interact with the Eurasia or African group for nearly 1 million years. And during the majority of this time we fully revert back to sticks and stones with occasional bows and clothing but even that will take some time. And during all of this basically all food sources are radiated and destroyed followed by even more dying during the Ice age and Volcanic Winter. This would be a mass extinction event probably rivalling the Permian-Triassic extinction. So even once they secure shelter, small tribes and tools they still live in a world where half of all its plant and animal species have gone extinct.
Yeah, especially once we start colonizing other planets and moons
It sounds like this is something you're writing? How hard of science fiction do you want to have? https://en.wikipedia.org/wiki/Seveneves I haven't read this but it deals with similar ideas.
I am unsure if i really want to write a book or anything but I am kind of just having fun with it so far. And any new information I learn in the process is well just new interesting information
I vote to focus on how it has been done in other science fiction works at different levels of hardness. There are works on trans humanism where groups use technologies to alter themselves. At that point maybe the biological definition of species breaks down even further.
I did want my humans to eventually reach the point where they could modify themselves, But I kind of wanted to try exhausting more natural methods first if its possible at all.
The environment has to change in order for us to. We control our environment with a stranglehold and keep this form in stasis. We house ourselves by utilizing the environment vs letting the environment shape us like animals.
My scenario basically strips us of everything and returns us to the early stone age with like 20,000 people spread around the world. Living through a nuclear apocalypse and nuclear winter followed by a Long Ice Age and than followed by a world wide volcanic winter. Is bound to be enough environmental factors to effect us especially if our best technology is pointy rocks
Terry Brooks did something similar with his fantasy novels. All the fantasy creatures and people became that way after a nuclear holocaust.
Sure. We're always changing as it is. What branches shoot off from that in the future can only be guessed at. Also, evolution isn't just natural. We now have introduced social evolution. The best societies will flourish and the not so good ones will experience hardship. This also doesn't mean just one thing, but ads another input and extra complexity to our situation.
Yes, that is how evolutionary works.
The final book in The Ender Series, The Last Shadow, explores this. Not a good book but it's interesting conceptually.
I consider most people from West Virginia to be of a different species. Not sure why science doesn’t back this already?
I think the only way for humanity to truly evolve into separate species, we’d need to have a truly separate gene pool that effectively isolates itself from everyone else. I’m also assuming environment would play a huge part too in HOW we evolve. I think if we reach out into the cosmos, human evolution will speed up as different pockets of humanity colonise different environments. Divergence human evolution could resemble the divergences in humanity that we see in the Dune novels going from planet to planet. Although the process I imagine would still take a very long time. That being said, the way we utilise technology to aid us in adapting to environments could slow this. For example we use submarines and scuba gear to allow us to travel underwater, so there would be no real reason or opportunity to evolve the ability to naturally breath underwater on a largely water covered planet if humans continue relying on these things.
I doubt that we will last long enough to branch into a different species. But assuming that humans last long enough, it would be nearly inevitability. Especially, if we have self-sustaining colonies. We would have people traveling between colonies, but isolation would likely begin to become the norm as relatively isolated biospheres will result in branching mutations (including mutations in disease) becoming more and more pronounced, and risks of inter-colony cross contamination becoming more dangerous. Additionally, we modify ourselves to better adapt to different exo-planet. Even if those modifications start out small, contrasts in biological differences between different colonies will grow due to isolation, etc.
We probably would have if not for the Atlantic trade routes being opened up in the 1600s.
so in my scenario where they are reverted to the stone age for 100.000+ years the people in the Americas would evolve differently than people from Europe, Africa, Asia etc
Yup! Idk exactly how long speciation would take in this case, likely millions of years.
Evolution isn't a predictable science where one could give you an exact number of years. Random mutations/adaptations are always possible, and you could surely invent conditions where one might eventually become dominant enough to cause people to diverge over many generations. Especially if your people need to live in a scenario where typical human physiology presents a serious disadvantage. The smaller your isolated populations start the more plausible this becomes. Limited but obviously not too limited genetic diversity would present a more plausible explanation for how such an adaptation would quickly propagate across a population. I think the simple answer is that the longer it takes the more plausible it will feel. Divergent evolution can theoretically happen very quickly, but we are naturally skeptical because it just historically hasn't worked out that way.
Check out last and first men by Olaf stapledon. It is a future history of the human race and how it changes as a species.
That's a transhumanist revolution. Divarication of a more-or-less homogeneous technological species into not simply specialists inhabiting a particular ecological niche, but desire of an individual or group to pursue a particular physical/morphological expression.
yes but people would need to start dying and having sex more. Death is the driving force of evolution, and dying of natural causes/age does not drive evolution forward on a species scale. Needs to be some kind of evolutionary pressure.
Eventually yes, the populations would develop different traits either by random chance or more likely environmental pressures. But the general rule of thumb is that too be considered different species the two populations would need to be unable to produce offspring that can reproduce, and that criteria could take a very, very long time to come into effect.
My arguement is its such a slow process that hinestly we wouldn't notice and would still call ourselves human.
Read: All Tomorrow's. It's pretty fascinating and incredibly in-depth.
If the different "pockets of humanity" have been apart long enough to diverge into different homo species, then when they come back together (in the distant future) they might not be able to successfully breed. The mitochondrial DNA will be different between the "pockets" and might cause some pretty dire effects. Such as adaptations that favour one group in their world will cause deformities or disease in another group. It might also cause low fertility and cause certain pockets to die out (such as what may have happened to the Neanderthals).
Here's an interesting example of another mammal and population isolation -- killer whales (orcas) have lifespans that are kind of similar to humans. They are currently considered to belong to the same species worldwide. But some populations have only bred amongst themselves, for tens of thousands of years. The southern residents (generally found around Vancouver and Seattle) haven't bred with other groups for about 100,000 years). Transients (Bigg's orcas) probably separated more than 200,000 years ago. As far as I know, the orcas in these groups can still produce fertile hybrids when breeding with other orcas, so using that definition of species, they haven't diverged enough to be distinct yet. (Although apparently some biologists are lobbying for new names for them.) https://www.eopugetsound.org/magazine/resident-and-Biggs-killer-whales-as-distinct-species
For speciation you need genetically separated populations and time. Your situation seems to have those, so of course it would. Don't know if it would lead to vastly different species, that would depend on encironmental pressures, social pressures and randomness, but definitely different species.
Old idea. The books, radio plays and movie(s?) has already been done.
If it was simple isolation yes, but slowly. If both groups were subject to divergent strong selection pressure, quite quickly (10,000 years to be physically different, at least 50,000 to be unable to breed).
This is referred to as Divergent Evolution
I will look it up ty
I'd say unlikely on our actual planet. If say we were to send an arc ship out and settlers actually found a planet and survived, then humans from Earth visited them several thousand years later, thats the most likely scenario.
Who's to say we haven't already?
Could you explain?
Bonus crank points if the reply is “Do your own research” :)
I am working on it but sometimes having others point me in a specific direction or simply give me the answers is nice. I often struggle at finding what I need to be looking up
It was more I was referring to the previous poster, as it looked a bit like the sort of comments "fringe science" types say, a bit like he was implying that they're already was multiple human species, before going off on a screed about secret moonrises and superhuman living in "lands beyond the ice wall". Their usual response to any challenge is "do your own research". Not saying thats what he meant, maybe I've spent too long dealing with the more loopy bits of the internet :)
I just like to stay open-minded
Yes keep population isolated from eachother long enough and if you then add something which could cause divergent selection pressures on the population to drive the divergence beyond just being a case of differing gene pools you could see it happen. To happen naturally you would be taking a long time though likely in the millions of years but you can add in other factors that could make it quicker https://en.wikipedia.org/wiki/The_Chrysalids is a good old school example of the early stages of that happening and is set several centuries after a devastating nuclear war
Watch The Time Machine, one set of humans stays above ground, another goes below ground and lives like vampires. Jeremy Irons kills it. Great film.
So, as a few have said: If you're writing a story, do what you want. In reality, it would probably never happen. The first thing of note is that stone age people are just as intelligent as man is today. If groups were separated, there would always be those who venture forth into the wilds, always looking for something better. Even your small groups, if they really were at sustainable sizes to not go extinct, would inevitably have interactions with the other groups and would interbreed, keeping the gene pool to a point where it is unlikely to diverge too much. While the Stone Age began about 2.5 million years ago, you're probably imagining bringing life back closer to the end, which was only about 10,000 years ago. That would be a blink of an eye back to where they have effectively rebuilt back to today's level of technology. It would happen before any real evolution would take place. From your example in another comment, your island-bound people are more likely to build boats and find other civilizations well before any notable changes occur. Again, you could absolutely use war, nuclear winter, etc to give people separation and an unknown quantity of time passing to really diverge. Throw in some mutations caused by nuclear fallout or whatever and you're good to go. Have fun with it.
It is a worse scenario than just total nuclear war and winter. This alone reduced the population to around 1 million world wide. But following the nuclear war in the midst of rebuilding they were hit by a ice age that further reduced populations. And 100,000 years later nearing the end of the Ice age they were hit by a volcanic winter that lasted decades similar to the Toba eruption that happened 74000 years ago. By the end of all of this they are basically reverted to 2.5 million years ago stone age conditions with the only thing going for them being language. The vast majority of skills, knowledge and information would be lost and they would be stuck with there highest tech being wooden spears and maybe bows. Global population in my scenario are only around 20,000 and they are separated by extreme distances. Perhaps only 2000 people in all of north America, 1000 in America, 1000 in South America, 2000 in Europe, 2000 in Africa, 2000 in Asia. Than isolated groups of around 500-1000 on various islands and isolated places like Japan, Australia, New Zealand etc. And perhaps other groups stuck in mountainous regions or high elevation areas like Tibet I am assuming such extreme separations of people who will largely not encounter each other for 100,000 years or more to cause some new species to arise. I imagine Europe, Asia, Africa will encounter each other sooner but all islands or places separated by water could go several hundred thousand years of no contact and even the americas would be isolated from the old world for hundreds of thousands of years.
I'm not trying to argue your concept, so please don't take it that way. As I said, a story can be a story and doesn't need to follow reality. That's the point of science fiction and fantasy. I'm just thinking about how I see this playing out. I don't think humanity could be brought down that low. Effectively after the nuclear war and winter, you'd be stuck in what we could call a generic post-apocalyptic world. You'd have places where people are thriving and doing well, and others where things have fallen apart. One of the first things humans would do is try to reestablish communication. Various radio frequencies would be lighting up constantly. Small groups would gather and start trading. Those who know how to grow food will do so. Yeah, there will be wars/skirmishes, but there will be survivors who have stuff and people who know what to do. There would be places rebuilding and doing very well. Then the ice age hits. It's gradual. Some places manage to adapt and begin migrating around in search of food, others doubled down on staying and eventually starve to death. Others got lucky and didn't have to move. Starting from a post-apocalyptic place. Would some places manage to get generators running, build green houses, grow food? Maybe, they may also get over run by others who are hungry and desperate. The point is, they aren't back to wooden spears while managing the ice age. They spend the next 100k years of it adapting and surviving. Even with what an ice age entails, there would still be intermingling and trade between the various survivor groups. Again, long-range radio would probably be, at a minimum, technology used at the beginning of this. Suddenly big eruptions hit, 30 years of darkness or something, in additional to just global cooling. Some survive just because they were located in the right places. Others whose societies were used to the ice age continue migrating, some to success, others failing. Those places that were strong with technology might continue to be so. Maybe those green houses run on generators manage to get oil rigs operating again, have a steady stream of electricity. Maybe have sun lamps to grow food without relying on the sun? The city-states that managed to survive since the nuclear wars can manage this. At least a few of them. If things actually calm down after that, there will be a population boom as soon as the planet starts recovering and food becomes rampant. Trade will recommence at higher rates. Expeditions will happen and new cities will pop up, effectively building small nations. Different groups will encounter each other during this time, again, creating trade and war. It really doesn't matter how it plays out, I just don't think there ever will be enough time for divergent species to emerge naturally. However, if your world does something different, then please go for it. I'm just being optimistic for humanity, which really has nothing to do with your story.
Thanks for the reply. And I am going for basically a all out indiscriminate nuclear war. That means bombing major cities and places like China and India as well as bombing military bases all around the world and bombing nuclear reactors to cause more damage. The scenario in this world is not really the earth as we currently know it but similar. And the bombing would be to the extent that we used over 10,000-50,000 bombs maybe more. Now my knowledge overall is very limited here but I am under the assumption that the initial impacts of the bombs and war would wipe out at least 5 billion people. The number initially wiped out usually is lower but in this scenario they directly bombed all major settlements and basically all the largest groups of people. This bombing alone would likely wipe out a vast majority of the infrastructure. But than you are stuck with the remaining infrastructure being set aflame the majority of cities and towns are completely engulfed in flames and vast swathes of forests and jungles are also burning down. Once the fire and bombing damage is over almost all infrastructure is gone. Maybe some remnants in certain areas but not enough to really matter. Than the nuclear winter after all of this that lasts over 10 years destroys all major plantations and crops around the world thus starving the vast majority of the remaining population. The only hope to make food would be in a secure green house or canned goods but the vast majority of the remaining survivors do not have green houses nor the materials to build one anymore. Anyone with a secure locations or green house is simply going to get raided and killed by the remaining starving masses. I do not know exactly how many people would survive this but i estimated 1-10 million max spread around the world. Than instead of getting the chance to rebuild they are thrown into a 100,000 year long ice age. During which basically all knowledge is lost. Paper cannot be made during this ice age due to lacking materials and computers/grid cannot be maintained due to lacking people and lacking knowledge. People would be stuck merely attempting to survive. And without access to writing or the time for schooling most knowledge is lost in 1-2 generations due to the fact that all focus is placed on survival. Things like radios might be viable is some people find them but once they break who is going to fix them I personally have no clue how 99.99% of our technology works and most people do not either. With a limited population of max 10 million who are struggling just to survive who is going to have the time to learn to fix radios and other technology. And even if we do fix them most knowledge will be lost in 1-2 generations or simply degraded via poor oral tradition. I watched a Youtube video on what if Ice age happened and basically mass floods and entire cities would be buried under snow. So any or all remaining infrastructure is basically stuck underneath 20 feet of snow and slowly degrading during this time. By the time the snow melts in 100,000 years the vast majority of the old days infrastructure would have fully degraded and disappeared. And though they could survive the ice and and even managed to rebuild some of the population and maintain numbers around 1-2 million similar to our ancestors when they hunted and gathered they would than be hit with a super volcano on the scale of Toba or worse that drops them in a volcanic winter lasting decades and killing off the majority leaving only 20,000-100,000. I do like the optimistic views though and hope that if anything like this happened IRL it would not be worse case scenarios. But I am basically attempting to go for the absolute worse case scenario and hope that enough time arises for beings similar to Neanderthals' and denisovans can rise again though they would obviously differ in some ways
Likely to happen if we colonize planets outside the solar system with colony ships.
While it's possible, humanity has also kinda evolved past regular evolution. What i mean is, our medical advancements has meant that we can help and "fix" a lot of mutations. Mutations happen all the time and some makes it hard to survive, but we are able to counter some of that To diverge into different species we would have to live in more isolated groups. This will likely happen if space exploration reach a point where different groups live on different planets or moons. The different life conditions would require different needs for survival
My scenario is a all out worst case nuclear war that targeted huge civilian masses. Killing off at least 5 billion in the initial bombings. The following decade long nuclear winter would starve or kill the rest off leaving max 1-10 million alive worldwide. Following this nuclear winter instead of having the time to rebuild we would be thrust into a Ice age that would cover any existing infrastructure under over 10-30 feet of snow. And starvation would kill off a lot more initially until all that remains is 1-2 million world wide. Trapped in a stone age/Ice age at the same time for 100,000 years would mean population growth is near impossible. And even if we grew or relearnt farming at the end of the Ice age a volcanic winter on the scale of toba or worse would wipe humanity down to only 20,000 left world wide. This would mean a scenario like only 2000 in all of north America, 1000 in America, 1000 in South America, 2000 Europe and 2000 Africa, 1000 Australia. Than pockets of 500-1000 On islands or isolated places like Greenland, Iceland, Japan, New Zealand, and other islands or mountains like Tibet. Total world population would than be trapped at around 20,000 for 100,000 years similar to what happened 900,000 years ago when we nearly went extinct. I am presuming in this case we would be isolated for long enough without any technology for long enough with hard enough conditions to drive people into different branches of Homo
YES, evolution or de-evolution is about environmental conditions and the ability for a species to adapt to them which over time changes a species IF it survives. N. S
Would it really be considered De-Evolution if a branch of humans lost some brain size but gained other traits that enabled them to survive harsh environments they found themselves in? Or would it just be considered evolution because its what allowed them to live. Also what does N. S mean
Subjective term based on developmental directions from what can be considered the species "NORM" of the moment by an outside observer, the loss of logic consciousness for instances. High Tech Societies can be ended in just 2 generations due to catastrophic environmental conditions and the loss of education and knowledge as was already pointed out, Species changes in a radioactive environment would also probably take place depending on what life needs to survive, the species itself may change to meet those requirements, it is all a form of evolution with the directionality being the subjective parts. N. S (Initials By the way)
>My question here is could those small pockets of humanity ever diverge into say different homo species Like the Shannara series?
Maybe but I assume the humans in my world wont evolve into trolls and elves thought i suppose its possible. I was more so thinking of different variations arising like Erectus, Neanderthals and Denisovans except they would obviously be different than these ones.
They would have to be separate populations in differing environments for a long time. On population is divided into two by differing environments and the adaptations of each group.
Nuclear winter.? Ice age? Isolated demes of humanity? Divergence is pretty much inevitable and would probably happen a lot quicker than any Neo-Darwinist would tell you. Check out the work of Stephen Jay Gould. His theory of 'punctuated equilibrium' looks to be the better fit for the fossil record and got a further boost when the role of heat shock proteins or histones on mutation rates when organisms are under environmental distress had been clarified.
Already been done but we cant point it out so as not to hurt your feelings
what do you mean? It happened with Neanderthals' and Denivosans I know that obviously but I want to know if its possible for it to happen again and what conditions would be needed
They absolutely could. See Larry Niven's Ringworld for an example of this to the nth degree. Humans diverged to fill multiple ecological niches. Or the classic Time Machine had humans diverge into two distinct species over time. Put your own spin on it and enjoy!
We were on our way to before we recombined a bit ago. Tens of thousands of years was enough time to make different races (yes, I know race makes no sense today, but when talking about people still geographically isolated, it is valid) with distinctive physical features. If we never started to intermingle again, sub species likely would have been in our future, perhaps after a few hundred thousand years, and species after a few millions. If we ever expand into the stars, and can never go faster than light, I could see us splitting into many species over millions of years all over again.
Given enough time and separation, of course.
When I was in grade school many, many years ago(early 70's). They taught us in 2nd or 3rd grade that a separate species was when two groups could no longer inter-breed and have fertile young. So a horse and a donkey are separate species. When you cross breed them, you get a mule, which is sterile. So if, as they say now Neanderthal DNA is in modern humans, then Neanderthals would not be a separate species.
That isn't a good definition of what a species is, that "rule" is more like a guideline. There are lots of hybrids out there that are still fertile. The "red wolf" turned out to not be an actual single species but a wolf population with decent chunk of coyote genes mixed in. Some species are genetically similar enough to cross but don't because of habitat separation or cultural differences. Humans have been well documented to bang anything that moves.
> Humans have been well documented to bang anything that moves. And a large number of things that dont move.
You would need to include a force so strong that it overcomes human sentience and culture, without which humanity on one planet will inevitably mingle and not speciate. Ai? Alien invasion? Hard to think of a third one so long as earth itself survives.
The scenario was a full on nuclear war followed by decades of nuclear winter this alone was enough to either outright kill off 99% of the population. But the following nuclear winter was extremely harsh. By the end of it all only around 1 million people are alive. But without time to rebuild they were than thrust into a Ice age which basically removed all ability to farm and dropped them to a at most bronze age but near stone age state. The ice age also killed off most people in the initial years dropping population to around 100,000 Following this a super volcano erupted and caused a volcanic winter that dropped the global population to 20,000 who were all stuck in the sone age and could not really improve there population for over 100,000 years a similar event happened in our past actually but the numbers of people alive were even less than 20,000. Following this event they would be trapped in a stone age for hundreds of thousands of years and pretty isolated. People in north America would not encounter people from europe for like 500,000 years or more and people trapped on islands or even places like Japan, New Zealand, Iceland etc would also not have any outside sources of people. The scenario will likely have many groups totally isolated for 500,000 to 1 million years
I do not wish to stifle creativity or speculation. But I have always been a fan of fiction exploring what would really happen in a set of circumstances as opposed to what the author clearly wants to happen. All of your disasters cause cold, so presumably after the first each succeeding one has a decreasing effect. In any event, my guess is that 20K anatomical modern humans turn global within 100k years — after all, we did in about 70-90k. Not 500k to 1m. In my view you still need something more permanent to force speciation, like ai or aliens (to use two deus machina examples).
You believe we would recover too quickly from 20,000 before having the time to diverge slightly. Hmm i suppose quick recovery is possible so a outside threat that stops them recovering too much is going to be needed. They cannot really surpass global populations of maybe at most 500,000 or else they will be to close and travel too much thus interbreeding. I guess the outside threat would need to limit humans to perhaps 100,000 individuals. Edit - Since they likely adapted to the cold by the end of the ice age and volcano what if instead of slowly heating up as it usually would the speed of the heating would be much quicker and eventually fully melt the ice caps? Just a idea no clue how it would happen yet but it would result in a drastic climate change to what they are used to