Most Human Evolution Wasn't Adaptive

In this video, I review an excellent paper hot-off-the-press by paleoanthropologists Lauren Schroeder and Rebecca Ackermann in the Journal of Human Evolution. In this paper, they discuss why we need to move beyond simple adaptationist storytelling and towards a rigorous, statistical evaluation of the evolutionary forces shaping human phenotypic variation. And, when we use statistical approaches, we find that most human evolution is non-adaptive, explained best by genetic drift and gene flow.

#evolution #humanevolution

[microtubules]

Excellent video! It is important to have a pluralistic view of various evolutionary forces, if we are ever going to understand the evolution of phenotypic traits.

[RileyRampant]

Thanks so much, Zach. This informs me that I need to invest more time in developing my understanding of the concepts of genetic drift and gene flow more thoroughly. I have a strong 'adaptationist' mindset which is apparently a bit reductionist. The intuition here is that the stochastic forces are those which provide the movement between 'adaptive peaks' perhaps. There has to be room created to phenotypically explore or hedge against changing conditions or novel habitats, right ?

[wcdeich]

I find it hard to believe skull shape differences between homo sapiens and Neanderthals was due to neutral variation. We just recently were able to predict brain tissue growth from Neanderthal DNA and it appears their neocortex was smaller and their foreheads did slope back more dramatically, leaving less space for that part of the brain. Also, we know Neanderthals had larger eyes and the visual cortex is in the back of the brain, where Neanderthals had that large skull bun.

[wcdeich]

But what was the p value for that correlation?

[NonSequiturShow]

What do you think of Fodor's "intensional" argument "against" natural selection...which isn't arguing natural selection doesn't exist, but merely it is a tautology, and it really doesn't explain anything or do much of the heavy lifting in variations of species because of co-extensive traits not being able to be determined what is actually being selected for? Natural selection is what Darwin had to work with, but he would have been amazed if he knew about what we now know about genetics....epistemics, gene flow and genetic drift.

Great video.

[Imoldman]

All that is wonderfull and very interesting. But life is simple and unforgiving, you either adapt or you die.

[TheFallibleFiend]

Wow! Thanks for this video. I need to watch this several times.

[Imoldman]

What it boils down to is:
As individuals we are products of our ancestor's history, our personal experiences, and the luck of the draw.
As a species we are products of our ancestor's history, our personal experiences, and the luck of the draw.

Except for the Monarch butterfly. Its a product of it's ancestor's history and it's most recent past 5 generations.😝😝😝😝😝

[pseudopetrus]

Ha, I'm first! Not the smartest but dedicated to learn!

[dinomiles]

Who cares it all in the past . Old info.