# How long would it take for two human populations to become a distinct species? **URL:** \ **Category:** Factual Questions\ **Created:** [October 12, 2009, 7:46pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570 "2009-10-12T19:46:20Z")\ **Posts on this page:** 14\ **Page:** 3
**Author:** ![kevlaw](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kevlaw/32/2281_2.png) [@kevlaw](https://boards.straightdope.com/u/kevlaw)\ **Post date:** [October 14, 2009, 3:06am UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/41 "2009-10-14T03:06:37Z")
> [@John\_Mace](#): > > The received wisdom in the biological community is that for large mammals like humans, about 500k years minimum. Maybe closer to 2M years. isn’t the neanderthal/sapiens split more recent than this? for how long were we separated before the split? ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [October 14, 2009, 3:14pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/42 "2009-10-14T15:14:30Z")
> [@kevlaw](#): > > isn’t the neanderthal/sapiens split more recent than this? for how long were we separated before the split? The number that one usually sees is about 500k years ago. Maybe closer to 700k. But not anywhere near 2M. I haven’t seen anyone who thinks the two populations are distinct species offer a number less than 500k. Not sure if we know how long the separation was. The earliest Homo remains in Europe are about 1.8M years old, but it’s unclear if that represents a separation date, or if there was gene flow back to African populations. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [October 14, 2009, 9:14pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/43 "2009-10-14T21:14:30Z")
Just to clarify that last post… Asking how long we were separated before the split doesn’t really make sense. We weren’t separated before the split, by definition. I think the most common view is that Neanderthals are descendant from _H. heidelbergensis_, or possibly from _H. antecessor_ (although there is debate over whether those are two separate species). ---
**Author:** ![Apollyon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/apollyon/32/4238_2.png) [@Apollyon](https://boards.straightdope.com/u/Apollyon)\ **Post date:** [October 14, 2009, 10:18pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/44 "2009-10-14T22:18:45Z")
> [@Chronos](#): > > Probably longer for humans than for other mammals our size, given our long lifespan and maturation time. A reasonable approximation would probably be that it takes a certain number of generations, and human generations are pretty long. (Caveat: IANAScientist 🙂 ) I recall reading that some species appear to be more “conservative” than others in their change rate though, and that Homo appears fairly rapid when contrasted with Pan – with the suggestion that our common ancestor was probably quite similar in size and shape to modern examples of Pan, and that even the common ancestor back to the split with gorillas was probably similar. Presumably a major driver for this is environment; once Pan (and Pan ancestors) were well adapted to their environment why change? Whereas if our ancestors became woodland dwellers (rather than rainforest) with altered diet and other factors, these pressures would have had a major selection effect. As for can / would breed – if Science Fiction has taught us anything, it is that once humanity gets out amongst the stars the aliens having funny noses, funny ears, tentacles, or being entirely composed of morphogenic protoplasm will not stand in the way of humans trying to mate with them. 🙂 ---
**Author:** ![wmfellows](https://avatars.discourse-cdn.com/v4/letter/w/c2a13f/32.png) [@wmfellows](https://boards.straightdope.com/u/wmfellows)\ **Post date:** [October 14, 2009, 10:19pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/45 "2009-10-14T22:19:45Z")
Returning to the OP question, which is interesting: > [@John\_Mace](#): > > If the two populations were to lose communication, and it looked to an outside, objective observer that it would be a permanent loss, then that observer could declare the two populations to be separate species then and there. Does this not seem a wee bit artificial, as you have an artificial event… Two separated non technology species would seem to present different issues than our humans. > [@Darwins\_Finch](#): > > On the other hand, it is unlikely that any taxonomist would declare the Zig population to be a separate species from the Zog population (assuming both were known), regardless of interbreeding, as morphologically, they would likely be identical (at least initially). If anything, the best consensus you might get is that Zigs and Zogs constitute discrete populations of _Homo sapiens_. Phylogenetically, the two would almost certainly be indistinguishable (especially if the individuals for each population were selected at random from the entirety of the human population of Earth), as well as being indistinguishable from the population at large, so they would again be classified as a single species. > > Which, of course, points out the additional problem that a species as a taxonomic entity may or may not conform to a species as a biological / evolutionary entity. > [@John\_Mace](#): > > :smack: I forgot the part about there needing to be a morphological difference between the populations. With a founding population of 1000 randomly chosen individuals, it shouldn’t take too many generations for that to appear. Throw in the high probability of those populations fracturing along racial/ethnic lines, and you accelerate that process. Throw in the possibility of that fracturing turning into warfare, and things change even faster. This probably gets to the core meaning of the OP question (I think the question of random selection from current populations particularly interesting). I believe above some rough estimate of ~500k years for objective (versus behavioural) genetic difference to develop to the point of a probable barrier to ‘natural’ (unaided ex-simple care) reproduction. Of course, it might be cleaner to remove the space travel concept and just pose a hypothetical as follows, for some reason (undefined in hypothetical), human population dies off except in Brazil and Austranesia. Technological collapse is included. Assuming no other biological factors, and assuming the South American and Austranesian populations that pass through the bottle neck at end crisis do not exceed 10k, how long do they have to be separated before “speciation” (reframing in this manner to remove the reconnection being technology driven, leaving aside the historical reality that recontact would almost certainly occur before speciation) ---
**Author:** ![Icerigger](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/icerigger/32/432_2.png) [@Icerigger](https://boards.straightdope.com/u/Icerigger)\ **Post date:** [October 14, 2009, 10:24pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/46 "2009-10-14T22:24:33Z")
Not until the year **802701**.😉 ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [October 15, 2009, 2:15am UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/47 "2009-10-15T02:15:48Z")
> [@kevlaw](#): > > isn’t the neanderthal/sapiens split more recent than this? for how long were we separated before the split? Still a debate on separate species or sub-species. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [October 15, 2009, 1:41pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/48 "2009-10-15T13:41:23Z")
> [@DrDeth](#): > > Still a debate on separate species or sub-species. Not much of one anymore, especially since the genetic data has not revealed any evidence of mixing despite thousands of years of co-existence. Sure, there will always be some lumpers who will argue sub-species (or 1 species), but the consensus view is species. Also, a subspecies is generally only recognized if the two populations occupy different territories, with little or no overlap. Two populations occupying the same territory would make an odd sub-species arrangement. The idea is that if those populations did occupy the same territory, they would become one breeding population. Here, we had two populations that had a geological barrier between them, preventing mating, but when that barrier was removed, there was little or no evidence of mating. Hence, species. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 15, 2009, 8:50pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/49 "2009-10-15T20:50:51Z")
How extensive is the genetic data, though? Last I heard, there was no evidence for Neanderthal mitochondrial DNA in modern humans, but that just means that there were few or no matings with Neanderthal mothers that led to offspring. But it still leaves open the possibility of matings between Neanderthal fathers and modern-human mothers, which might plausibly occur if they viewed us as more “feminine” and we viewed them as more “masculine”. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [October 15, 2009, 10:40pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/50 "2009-10-15T22:40:23Z")
> [@Chronos](#): > > How extensive is the genetic data, though? Last I heard, there was no evidence for Neanderthal mitochondrial DNA in modern humans, but that just means that there were few or no matings with Neanderthal mothers that led to offspring. But it still leaves open the possibility of matings between Neanderthal fathers and modern-human mothers, which might plausibly occur if they viewed us as more “feminine” and we viewed them as more “masculine”. The genetic data is spares, but that’s all we have to go from. It’s certainly possible that some future research will reveal a different result, but the facts as we know them now don’t support the hypothesis that we were the same species. Whether interbreeding was prevented by physical or cultural reasons (or some combination) we don’t know. Frankly, I think it would be astounding if the two populations couldn’t interbreed and produce viable offspring, even if they didn’t. There are no large mammals extant today which are that closely related and that can’t interbreed. Chimps and bonobos split about 2M years ago, and the can interbreed. ---
**Author:** ![Contrapuntal](https://avatars.discourse-cdn.com/v4/letter/c/e274bd/32.png) [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)\ **Post date:** [October 16, 2009, 5:59pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/51 "2009-10-16T17:59:17Z")
> [@wmfellows](#): > > It most certainly is, and Mace and _Colibimbri_, among others, have given factual responses. I don’t know why, but this garbling of his name cracks me up. What’s a bimbri? A male bimbo? 😉 ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [October 16, 2009, 6:44pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/52 "2009-10-16T18:44:25Z")
It’s a male bimbo hummingbird. I’ll leave it to everyone’s imagination what that looks/acts like. 🙂 ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 16, 2009, 7:22pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/53 "2009-10-16T19:22:40Z")
> [@John\_Mace](#): > > It’s a male bimbo hummingbird. I’ll leave it to everyone’s imagination what that looks/acts like. 🙂 Probably like a cross of a hummingbird with [this guy](http://www.bimbobakeriesusa.com/gfx/Bimbo_HoneyWheat_Illust.jpg). I have to admit I thought **Colibimbri** was pretty funny myself.😃 ---
**Author:** ![wmfellows](https://avatars.discourse-cdn.com/v4/letter/w/c2a13f/32.png) [@wmfellows](https://boards.straightdope.com/u/wmfellows)\ **Post date:** [October 16, 2009, 11:38pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570/54 "2009-10-16T23:38:30Z")
> [@Colibri](#): > > Probably like a cross of a hummingbird with [this guy](http://www.bimbobakeriesusa.com/gfx/Bimbo_HoneyWheat_Illust.jpg). > > I have to admit I thought **Colibimbri** was pretty funny myself.😃 Oh fuck off… i am sure I could dream up a defence… God-damned hummingbirds. No one has taken up my restatement, you whiners. (and yes okay I spelled the username as I mentally pronounce it, and I have no good explanation why…) [Previous page](https://boards.straightdope.com/t/how-long-would-it-take-for-two-human-populations-to-become-a-distinct-species/513570.md?page=2)