40 K years sounds like a long time, but there's a lot of evidence that human DNA has hardly changed at all in that time. I.e., for making fancy bracelets, our ancestors back then were just as bright, artistic, etc. as we are now so that given the materials, tools, and technology they had then they could do as well as we could and we couldn't do any better. I don't know about the "extinct human species", but there is there is a simple argument based on (i) mitochondrial DNA and (ii) a simple observation.
We take humans (a) in western Europe and (b) east Asia. For (i) we argue that from the rate of change in mitochondrial DNA the most recent common ancestor was about 40 K years ago. A guess is that that ancestor was in or near present India. So, some descendants walked NW to western Europe and others walked NW to east Asia.
Now for (ii), compare western Europeans and east Asians on essentially any attributes you want and observe that they are very close. Well, necessarily each is even closer to their most recent common ancestor: I.e., to get the DNA changes from western Europe to east Asia, have to have the changes going back in time to the most recent common ancestor and then more changes forward in time from that ancestor to east Asia; i.e., each of western Europe and east Asia is closer to the common ancestor than to each other and, since Europe and Asia are close now, they are even closer to their common ancestor.
So, conclusion: We are still really close to the most recent common ancestor.
Or, in simple terms, take the that ancestor, wash them up and give them some modern clothes, and they'd look just like us except with a different language. And they might be wearing a very nice bracelet.
I agree with you. For some reason, a significant proportion of people think that people in the past couldn't perceive the color blue and/or were hallucinating gods' voices in a schizophrenic kind of way (bicameral mind hypothesis).
40k years is between 1000 and 2000 generations. Why would it be unreasonable to think there could be significant genetic drift over that many iterations?
We have bred entirely new strains of dogs or other livestock that are almost unrecognizable from the starting population in a fraction of that time.
What we have done to plants through relatively unsophisticated selection pressure is even more illuminating.
Why humanity would be immune from similar processes, I cannot understand.
> 40k years is between 1000 and 2000 generations. Why would it be unreasonable to think there could be significant genetic drift over that many iterations?
Sure, it looks like there "could be". So what is interesting is the evidence I presented that there hasn't been.
Human DNA has changed more in the last 50,000 years than in the 1 million before that. The pressures of large-scale organization, climate changes etc spurred continuous selection.
But, from what I presented, you are saying that the DNA changes of the last 50,000 years happened essentially the same and independently in (i) Europe and (ii) Asia.
Generally in evolution is it more likely that DNA twice the same is from a common ancestor instead of two independent, at least separate, cases of the changes.
For the influences of climate change, that seemed to vary: My guess is that Europe suffered and changed much more from the big ice sheets than Asia. So, it would be more likely that the DNA you say came from climate change came from common ancestors (from still earlier climate change, etc.) than from two independent responses to two (not very similar) climate changes.
Supposedly eyes with lenses and retinas evolved at least twice separately, but that took a very long time and is still considered amazing.
We take humans (a) in western Europe and (b) east Asia. For (i) we argue that from the rate of change in mitochondrial DNA the most recent common ancestor was about 40 K years ago. A guess is that that ancestor was in or near present India. So, some descendants walked NW to western Europe and others walked NW to east Asia.
Now for (ii), compare western Europeans and east Asians on essentially any attributes you want and observe that they are very close. Well, necessarily each is even closer to their most recent common ancestor: I.e., to get the DNA changes from western Europe to east Asia, have to have the changes going back in time to the most recent common ancestor and then more changes forward in time from that ancestor to east Asia; i.e., each of western Europe and east Asia is closer to the common ancestor than to each other and, since Europe and Asia are close now, they are even closer to their common ancestor.
So, conclusion: We are still really close to the most recent common ancestor.
Or, in simple terms, take the that ancestor, wash them up and give them some modern clothes, and they'd look just like us except with a different language. And they might be wearing a very nice bracelet.