Monday, August 7, 2017

We're still evolving (and not just politician's positions on controversial issues)

I am reading three different books right now that explore the connection and interweaving pressures between biological evolution and human culture, all three coming to the conclusion that biology sets some parameters on culture but that within those parameters, culture drives evolution.

It is both fascinating and I am deeply troubled by this approach. All humans are equally human and all have inherent value in their humanity. I take that as a starting point. Talk of recent and variant evolution poses a risk to that bedrock normative position. As long as everyone accepts the predicate assumption that there is inherent worth in every human, there isn't an issue but the talk of regional variation makes me nervous.

There are a couple of research papers consonant with these books which have come across my desk.

From Human Biological and Psychological Diversity by Bo Winegard, Mark Winegard, and Brian B Boutwell. Abstract:
Many evolutionary psychologists have asserted that there is a panhuman nature, a species typical psychological structure that is invariant across human populations. Although many social scientists dispute the basic assumptions of evolutionary psychology, they seem widely to agree with this hypothesis. Psychological differences among human populations (demes, ethnic groups, races) are almost always attributed to cultural and sociological forces in the relevant literatures. However, there are strong reasons to suspect that the hypothesis of a panhuman nature is incorrect. Humans migrated out of Africa at least 50,000 years ago and occupied many different ecological and climatological niches. Because of this, they evolved slightly different anatomical and physiological traits. For example, Tibetans evolved various traits that help them cope with the rigors of altitude; similarly, the Inuit evolved various traits that help them cope with the challenges of a very cold environment. It is likely that humans also evolved slightly different psychological traits as a response to different selection pressures in different environments and niches. One possible example is the high intelligence of the Ashkenazi Jewish people. Frank discussions of such differences among human groups have provoked strong ethical concerns in the past. We understand those ethical concerns and believe that it is important to address them. However, we also believe that the benefits of discussing possible human population differences outweigh the costs.
And then there is Recent acceleration of human adaptive evolution by John Hawks, et al.
Genomic surveys in humans identify a large amount of recent positive selection. Using the 3.9-million HapMap SNP dataset, we found that selection has accelerated greatly during the last 40,000 years. We tested the null hypothesis that the observed age distribution of recent positively selected linkage blocks is consistent with a constant rate of adaptive substitution during human evolution. We show that a constant rate high enough to explain the number of recently selected variants would predict (i) site heterozygosity at least 10-fold lower than is observed in humans, (ii) a strong relationship of heterozygosity and local recombination rate, which is not observed in humans, (iii) an implausibly high number of adaptive substitutions between humans and chimpanzees, and (iv) nearly 100 times the observed number of highfrequency linkage disequilibrium blocks. Larger populations generate more new selected mutations, and we show the consistency of the observed data with the historical pattern of human population growth. We consider human demographic growth to be linked with past changes in human cultures and ecologies. Both processes have contributed to the extraordinarily rapid recent genetic evolution of our species.
Both are consistent with the view that since the emergence of anatomically modern humans some 50,000 years ago, 1) human evolution has continued, 2) human evolution has accelerated, 3) human evolution creates a divergence of local populations, and 4) culture is an additional driver of evolution beyond just environment.

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