[extropy-chat] New Path For Evolutionary Psychology

Lee Corbin lcorbin at tsoft.com
Sun Mar 19 02:43:31 UTC 2006

>From innate violent tendencies of the Yanomamo, to *trust*,
to the cognitive ability of Jews, it's a watershed event
when a mainstream publication like the NYT can print notions
that were complete anathema only a mere twenty years ago:


    ADAPTATION                     By NICHOLAS WADE
    Published in the New York Times: March 12, 2006

    EAST ASIAN and European cultures have long been very different, Richard E.
    Nisbett argued in his recent book "The Geography of Thought." East Asians tend to
    be more interdependent than the individualists of the West, which he attributed
    to the social constraints and central control handed down as part of the
    rice-farming techniques Asians have practiced for thousands of years.

    A separate explanation for such long-lasting character traits may be emerging
    from the human genome. Humans have continued to evolve throughout prehistory and
    perhaps to the present day, according to a new analysis of the genome reported
    last week by Jonathan Pritchard, a population geneticist at the University of
    Chicago. So human nature may have evolved as well.

    If so, scientists and historians say, a fresh look at history may be in order.
    Evolutionary changes in the genome could help explain cultural traits that last
    over many generations as societies adapted to different local pressures.

    Trying to explain cultural traits is, of course, a sensitive issue. The
    descriptions of national character common in the works of 19th-century historians
    were based on little more than prejudice. Together with unfounded notions of
    racial superiority they lent support to disastrous policies.

    But like phrenology, a wrong idea that held a basic truth (the brain's functions
    are indeed localized), the concept of national character could turn out to be not
    entirely baseless, at least when applied to societies shaped by specific
    evolutionary pressures.

    In a study of East Asians, Europeans and Africans, Dr. Pritchard and his
    colleagues found 700 regions of the genome where genes appear to have been
    reshaped by natural selection in recent times. In East Asians, the average date
    of these selection events is 6,600 years ago.

    Many of the reshaped genes are involved in taste, smell or digestion, suggesting
    that East Asians experienced some wrenching change in diet. Since the genetic
    changes occurred around the time that rice farming took hold, they may mark
    people's adaptation to a historical event, the beginning of the Neolithic
    revolution as societies switched from wild to cultivated foods.

    Some of the genes are active in the brain and, although their role is not known,
    may have affected behavior. So perhaps the brain gene changes seen by Dr.
    Pritchard in East Asians have some connection with the psychological traits
    described by Dr. Nisbett.

    Some geneticists believe the variations they are seeing in the human genome are
    so recent that they may help explain historical processes. "Since it looks like
    there has been significant evolutionary change over historical time, we're going
    to have to rewrite every history book ever written," said Gregory Cochran, a
    population geneticist at the University of Utah. "The distribution of genes
    influencing relevant psychological traits must have been different in Rome than
    it is today," he added. "The past is not just another country but an entirely
    different kind of people."

    John McNeill, a historian at Georgetown University, said that "it should be no
    surprise to anyone that human nature is not a constant" and that selective
    pressures have probably been stronger in the last 10,000 years than at any other
    epoch in human evolution. Genetic information could therefore have a lot to
    contribute, although only a minority of historians might make use of it, he said.

    The political scientist Francis Fukuyama has distinguished between high-trust and
    low-trust societies, arguing that trust is a basis for prosperity. Since his 1995
    book on the subject, researchers have found that oxytocin, a chemical active in
    the brain, increases the level of trust, at least in psychological experiments.
    Oxytocin levels are known to be under genetic control in other mammals like

    It is easy to imagine that in societies where trust pays off, generation after
    generation, the more trusting individuals would have more progeny and the
    oxytocin-promoting genes would become more common in the population. If
    conditions should then change, and the society be engulfed by strife and civil
    warfare for generations, oxytocin levels might fall as the paranoid produced more

    Napoleon Chagnon for many decades studied the Yanomamo, a warlike people who live
    in the forests of Brazil and Venezuela. He found that men who had killed in
    battle had three times as many children as those who had not. Since personality
    is heritable, this would be a mechanism for Yanomamo nature to evolve and become
    fiercer than usual.

    Since the agricultural revolution, humans have to a large extent created their
    own environment. But that does not mean the genome has ceased to evolve. The
    genome can respond to cultural practices as well as to any other kind of change.
    Northern Europeans, for instance, are known to have responded genetically to the
    drinking of cow's milk, a practice that began in the Funnel Beaker Culture which
    thrived 6,000 to 5,000 years ago. They developed lactose tolerance, the unusual
    ability to digest lactose in adulthood. The gene, which shows up in Dr.
    Pritchard's test, is almost universal among people of Holland and Sweden who live
    in the region of the former Funnel Beaker culture.

    The most recent example of a society's possible genetic response to its
    circumstances is one advanced by Dr. Cochran and Henry Harpending, an
    anthropologist at the University of Utah. In an article last year they argued
    that the unusual pattern of genetic diseases found among Ashkenazi Jews (those of
    Central and Eastern Europe) was a response to the demands for increased
    intelligence imposed when Jews were largely confined to the intellectually
    demanding professions of money lending and tax farming. Though this period lasted
    only from 900 A.D. to about 1700, it was long enough, the two scientists argue,
    for natural selection to favor any variant gene that enhanced cognitive ability.

    One theme in their argument is that the variant genes perform related roles,
    which is unlikely to happen by chance since mutations hit the genome randomly. A
    set of related mutations is often the mark of an evolutionary quick fix against
    some sudden threat, like malaria. But the variant genes common among the
    Ashkenazi do not protect against any known disease. In the Cochran and Harpending
    thesis, the genes were a response to the demanding social niche into which
    Ashkenazi Jews were forced and the nimbleness required to be useful to their
    unpredictable hosts.

    No one has yet tested the Cochran-Harpending thesis, which remains just an
    interesting though well worked out conjecture. But one of its predictions is that
    the same genes should be targets of selection in any other population where there
    is a demand for greater cognitive skills. That demand might have well have arisen
    among the first settled societies where people had to deal with the quite novel
    concepts of surpluses, property, value and quantification. And indeed Dr.
    Pritchard's team detected strong selection among East Asians in the region of the
    gene that causes Gaucher's disease, one of the variant genes common among

Perhaps the time isn't far off when even in polite society
it will be possible to utter the dread "e-word".


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