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paleoanthropology, genetics and evolution

post-Industrial evolution

  • Fogel profile

    Tue, 2011-04-26 18:13 -- John Hawks

    The NY Times has a profile of economist Robert W. Fogel ("Technology Advances; Humankind Supersizes"). Fogel, along with other historical economists, has worked to document the changes in human stature, mass and health during the last few hundred years. These changes were mostly not evolutionary. That is, it wasn't genetic change that made us bigger, for the most part.

    The documentation of these trends has made for a fascinating series of historical studies. The occasion for the profile is the upcoming release of a book by Fogel and colleagues summarizing the decades of work.

    To take just a few examples, the average adult man in 1850 in America stood about 5 feet 7 inches and weighed about 146 pounds; someone born then was expected to live until about 45. In the 1980s the typical man in his early 30s was about 5 feet 10 inches tall, weighed about 174 pounds and was likely to pass his 75th birthday.

    Across the Atlantic, at the time of the French Revolution, a 30-something Frenchman weighed about 110 pounds, compared with 170 pounds now. And in Norway an average 22-year-old man was about 5 ½ inches taller at the end of the 20th century (5 feet 10.7 inches) than in the middle of the 18th century (5 feet 5.2 inches).

    This stuff is tremendously important for human biologists to understand, and the data have become enormously richer in many respects as historical economists have drawn together records about military conscripts, food allowances and disease rates.

    The second part of the profile goes into some areas of criticism for Fogel (he focuses mainly on nutrition, other scholars argue for the importance of different causes). I think it is time to integrate a more evolutionary view into the data on recent secular trends. The Framingham study and other longitudinal surveys have demonstrated differential fertility associated with stature in contemporary industrialized societies. Evolution is happening, and does not necessarily go in the same direction as the secular increase in stature. Meanwhile, population differences in stature and other traits owe to a deeper history that includes different causes.

    Tags: 
    industrialization
    health
    profiles
    post-Industrial evolution
    history
    economics

  • Humans still evolving...

    Sun, 2009-10-25 22:45 -- John Hawks

    Time has a story about Stephen Stearns and colleagues' work characterizing ongoing selection using the Framingham Heart Study sample:

    If these trends were to continue with no cultural changes in the town for the next 10 generations, by 2409 the average Framingham woman would be 2 cm (0.8 in) shorter, 1 kg (2.2 lb.) heavier, have a healthier heart, have her first child five months earlier and enter menopause 10 months later than a woman today, the study found. "That rate of evolution is slow but pretty similar to what we see in other plants and animals. Humans don't seem to be any exception," Stearns says.

    I haven't had a chance to see the new study yet, and I'll do a little review when I get it. Jerry Coyne has some more information based on a preprint.

    My students have heard me say many times that it would take a sample of thousands of people to test the hypothesis of neutrality within today's population. Well, Framingham is one such sample, and it's not surprising that some things would be found significantly to affect fitness.

    The Time article mentions our work on recent evolution in a very positive way. Of course, the Framingham sample isn't suitable for testing what has been going on during the last 40,000 years; it is about mass selection on phenotypes in the present American population. That will involve mostly selection on standing variants, things that are already common in the population. Some of those may be things that were increasing in the past, others not -- some may even be reversals in direction compared to pre-industrial times. And there's no predicting how they might change in the future, as we continue to change our environment out from under ourselves.

    I've seen a few comments that we shouldn't trust the sample because it's unrepresentative, too small, etc. I think people may be overlooking the fact that the Framingham Heart Study is bigger than the census sizes of many species in nature. You can detect selection on phenotypes in this sample, and they surely know the heritabilities of many of them. But I'll have to see the paper.

    Tags: 
    health
    Holocene
    acceleration
    post-Industrial evolution
    recent selection
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