Suppose the races of the various continents were separated by barriers which were not overcome (seas, mountains). Would we all be separate species (or unmatable subspecies) today?
The important question is how long they are isolated. And the native Americans prove that a simple few thousand years won’t be enough.
It apparently takes longer than 100,000 years, which is approximately how long ago humans last were a nearly homogenous population. This is about 4000ish generations. ( though there has been much population interbreeding in that time).
Since no one really knows how long it would take to differentiate into seperate species, and it would depend upon many random factors, this question might be unanswerable.
not a question you could answer, evolution isn’t like some magic force that hovers around and mutates things, it could happen in a few generations, could go a million years without any major change. so… more than ten years, less than a billion sounds about the most specific guess you can get.
Unlikely. Modern humans were a small (< 10k, > 1k) group living in Africa as recently as 65k yrs ago. The different races did not begin to appear until some time after that, when we left Africa for the other continents.
If we look at Neanderthals as a seperate species (and that’s debatable), we appear to have had a common ancestor with group about 500k yrs ago.
It would be reasonable to assume that 250k yrs would be a minimum time length needed, barring any extraordinary circumstances.
Wolves and coyotes, for example, probably split off as seperate species over 1M yrs ago, and yet are interfertile today.
n.b.: The current genetic evidence (and it’s very sparse) indicates that modern humans and Neanderthal did not interbreed. But it doesn’t prove that the two groups couldn’t have interbred.
This may be off topic, but I vaguely remember an article a few years ago (New Scientist? Sci Amer?) that stated that there were actually fairly significant genetic differences among the Indian castes. Not a new species, OBVIOUSLY. But it shows that there’s more than regular biology and genetics at work when we’re talking about humans.
Before we have to worry about new human species, we’re going to see things go seriously wacky with the body-modification fetishists, the transhuman and posthuman advocates, genetic engineering, etc.
Sorry I can’t come up with the cite, but if any of you know enough about genetics to appreciate the details, you’re a lot likelier to be able to find the original article than I am.
Is this close DD?
That’s probably a bit misleading. Maybe humans haven’t been a homogenous population for that long, but there was constant genetic transference between those population for all except the past 10, 000 years or so. In other words there was never an opportunity for allopatric speciation to occur. Any gene that was produced in China would have found its way to France if it were useful enough, and vice versa. It’s very hard if not impossible to get speciation in those circumstances no matter how long you’ve got to play with.