David Friedman On Evolution And Human Nature

David Friedman says that while Leftists generally accept that evolution occurred they reject all implications evolution has for human nature.

People who say they are against teaching the theory of evolution are very likely to be Christian fundamentalists. But people who are against taking seriously the implications of evolution, strongly enough to want to attack those who disagree, including those who teach those implications, are quite likely to be on the left.

I think he is right on his basic points. The bulk of the (fairly unscientific) attacks on the idea of genetic causes of differences in intellectual performance come from the Left. The argument for the primacy of social environment as the biggest force determining our intelligence comes from the Left. Yet some genetic theorists find evidence that local selective pressures exerted even over several hundred years can cause big changes in cognitive function. Friedman starts out focusing on differences between the sexes in cognitive function.

Consider the most striking case, the question of whether there are differences between men and women with regard to the distribution of intellectual abilities or behavioral patterns. That no such differences exist, or if that if they exist they are insignificant, is a matter of faith for many on the left. The faith is so strongly held that when the president of Harvard, himself a prominent academic, merely raised the possibility that one reason why there were fewer women than men in certain fields might be such differences, he was ferociously attacked and eventually driven to resign. Yet the claim that such differences must be insignificant is one that nobody who took the implications of evolution seriously could maintain. We are, after all, the product of selection for reproductive success. Males and females play quite different roles in reproduction. It would be a striking coincidence if the distribution of abilities and behavioral patterns that was optimal for one sex turned out to also be optimal for the other, rather like two entirely different math problems just happening to have the same answer.

Human male and female brains differ in fundamental ways. For example, women have a higher ratio of white matter to gray matter than men. The scientific literature on male-female differences in cognition is now enormous. Yet a president of Harvard (Larry Summers) can still get forced from office in part because he took that scientific literature seriously.

Speaking as someone who thinks the evidence for the theory of evolution is overwhelming I am very disappointed at how evolution has been walled off from most discussions of human nature in the political sphere. Among most secularists (who like to fancy themselves as more scientific than the Christians) I see widespread embrace of a sort of modern Cartesian dualism where instead of placing the mind in a supernatural realm the genes that code for the mind are viewed as immune to evolutionary selective pressures. We are supposed to believe that humans have evolved so far that they've escaped the genes that code for their minds and that at birth the human mind is a Blank Slate (tabula rasa) almost totally molded by its environment.

I see the Left's Blank Slate as an even worse model for understand human nature than the fundamentalist Christian Original Sin view of human nature. The Original Sin model maps closer to what evolution produced: selfish desires that got selected for in order to cause behaviors that boost reproductive fitness. In the Original Sin model the idea that evil can be defeated in this world is laughable because the devil is whispering in everyone's ear and the battle between good and evil is constant. The temptations of sin are the desires and instincts placed in us by millions of years of natural selection. So the idea of Original Sin hits a lot closer to the truth than the view that we can perfect humans with smarter social policies. New Soviet Man is the antithesis of what a Darwinist ought to think is possible to achieve in human societies.

A June 2007 article from Plos Genetics, Localizing Recent Adaptive Evolution in the Human Genome, provides examples of localized evolution of cognitive function.

Several genes with functional roles in the development and function of the nervous system show very strong evidence (CLR p < 10−5) for a recent selective sweep. For example, SV2B, a gene encoding a synaptic vesicle protein with highest expression during brain development [36], exhibits strong evidence for a selective sweep in the African-American sample. Likewise, the protein encoded by DAB1 plays a developmental role in the layering of neurons in the cerebral cortex and cerebellum [37], and exhibits strong evidence for a selective sweep in the Asian sample. Other nervous system genes with strong evidence for a selective sweep include two candidate genes for Alzheimer disease (APPBP2 and APBA2) that bind the amyloid-beta precursor protein, two genes (SKP1A and PCDH15) with a role in sensory development, and several others with various roles in nervous system development and function (PHACTR1, ALG10, PREP, GPM6A, and DGKI).

A March 2007 article from Plos Biology, A Map of Recent Positive Selection in the Human Genome, finds plenty of signs up local cognitive evolution.

Recent articles have proposed that genes involved in brain development and function may have been important targets of selection in recent human evolution [8,9]. While we do not find evidence for selection in the two genes reported in those studies (MCPH1 and ASPM), we do find signals in two other microcephaly genes, namely, CDK5RAP2 in Yoruba, and CENPJ in Europeans and East Asians [46]. Though there is not an overall enrichment for neurological genes in our gene ontology analysis, several other important brain genes also have signals of selection, including the primary inhibitory neurotransmitter GABRA4, an Alzheimer's susceptibility gene PSEN1, and SYT1 in Yoruba; the serotonin transporter SLC6A4 in Europeans and East Asians; and the dystrophin binding gene SNTG1 in all populations.

This all is unsurprising and I expect much more evidence to be uncovered of cognitive adaptations to local environments. For example, fishermen had different cognitive demands placed on them than farmers. With a boat one is in constant danger of death and one needs to be much more careful. The ideal personality for a crew member of a fishing boat is probably different than the ideal personality for a sheep herder and the ideal personality for a sheep herder is probably different than that for a tiller of soil. So an area with lots of coastlines and little farmable land probably have different average personality types than areas with lots of tillable soil.

While some will rush to dismiss these speculations evidence has already begun to emerge that genetic variations that affect cognitive function make people more adapted in some environments and less adapted in other environments. For example, a genetic variation that contributes to hyperactivity boosts success of nomadic tribesmen but makes them less successful when they move into urban environments. A lot of people with Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD) probably have what we consider a disability in industrial society because their ancestors did better by having the genes that cause these cognitive states. Today ADHD causes people to be more violent and criminal.

While politically correct dogma would have us believe that humans are extremely similar excepting for appearances the latest genetic research shows that human groups are evolutionarily diverging from each other and in many ways. But these insights from research are entirely missing from political discussions.

As my regular readers know, I think we are on the verge of an enormous explosion of discoveries about human genetics and the roles genes play in causing differences in cognitive function, athletic performance, health, and other aspects of human function. People who anchor their political beliefs in either supernatural religious or secular religious belief systems are going to find the foundations of their beliefs blown away by this coming torrent of discoveries.