Tuesday, May 13, 2014

How Civilization accelerated Human Evolution

I read The 10,000 Year Explosion, How Civilization Accelerated Human Evolution by Gregory Cochran and Henry Harpending, 2009.  

If “natural selection” isn’t at work raising intelligence and adapting us to new technology then it is something very like it.  Cochran and Harpending marshal a number of evidences demonstrating key evolutionary advances.  Our becoming lactose tolerant for example enabled our ancestors to raise cows for milk giving them a 5 to 1 advantage over those who raised cattle for food.  

The “10,000 year explosion” in their title refers to agriculture.  When our ancestors could stop wandering about with herds of cattle and settle down in fixed locations to farm, this necessitated the creation of ‘elites’ needed to guard their property, govern disputes and assemble them in order to fight groups of intruders bent on robbing them of their property and women.  But towns centered on clusters of farms had advantages over wandering tribes of herders – eventually.  Attila and his Huns were herders rather than farmers, but the potential was there for farmers to produce larger armies.

An increase in intelligence was required in order for homo sapiens to learn how to farm.  And then further increases as well as other evolutionary changes were required in order to learn how to reduce disease, adapt to eating foods that were not significant when they wandered as hunter-gatherers or herders.

Cochran and Harpending end with a discussion of the Ashkenazi Jew.  Evidence exists, they argue, that their intelligence (and peculiar diseases) were not created by “bottlenecks” but by natural selection.  These Jews (as opposed to Jews living in Muslim countries for example) worked in “white collar” activities as money lenders and in more modern times especially starting in the 19th century in science and mathematics, excelled.  They began doing this about 800 years ago; then in the early 1800s when many of them opened up to enlightenment ways of thinking, their money-lending intelligence enabled them to excel in mathematics and science. 

Cochran and Harpending allude to the possibility that Israel being a cross-road to a number of invasions and a lot of traffic may have benefitted from increased genetic variation, but they find no indication that Jews 2000 years ago were smarter than the norm for that time.  Perhaps that is why they didn’t draw a parallel to the modern-day U.S.   We have had an influx of the brightest people from all over the world especially after World War II.  Hasn’t the resultant genetic variability enhanced intelligence in a significant few?  American entrepreneurs do seem to be developing new technology at a greater rate than other nations.  Could the reason for this be to some extent due to so many bright people having moved to the U.S. in the 20th century?

And I also wondered about the heritability of things learned.  The Ashkenazi Jews learned money lending and this enabled them to become leading scientists and mathematicians in the 20th century.   Cochran and Harpending don’t go beyond “natural selection” to account for the reasons for this.  Somehow in the past 800 years the smarter Ashkenazi Jews had more children than the dumber ones and thus were able to produce Einstein-level brilliance by the 20th century.  And yet Cochran and Harpending describe some serious illnesses that are also found in the Ashkenazi Jews which would seem to argue against inordinately larger families for these Jews than the norm. 

Everyone on this forum knows that if we study a subject a lot and then keep on studying it; eventually we will know more about it than almost anyone we know – assuming we start our study with adequate intelligence.   This seems to me what the Ashkenazi Jews started doing 800 years ago.  But is natural selection an adequate explanation for what happened in the 20th century, for Einstein for example?   We know there are genetic “triggers” of various sorts; mightn’t the intense study needed for mastering money-lending have triggered an intellectual benefit that was to some extent heritable?  Maybe not, but it doesn’t seem as though there were enough generations for natural selection to explain those results.

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