Friday, September 11, 2009

Thoughts on Climate Change

In the August 2009 issue of Scientific American (no link; they now require a digital subscription; your library has the issue), author Kate Wong considers some of the reasons the Neanderthals may have died out, since there's now considerable evidence that they coexisted with homo sapiens for around 15,000 years.  Analysis of isotopes trapped in "primeval ice, ocean sediments, and pollen retrieved from such locales as Greenland, Venezuela and Italy" seems to show that, during a period known as "oxygen isotope stage 3" (OIS-3), which ran from around 65,000 years ago to 25,000 years ago, the climate became wildly unstable heading into the last glacial maximum: 
So rapid were these oscillations that over the course of an individual's lifetime, all the plants and animals that a person had grown up with could vanish and be replaced with unfamiliar flora and fauna.  And then, just as quickly, the environment could change back again.
The Neanderthals were preliterate; they had no way to pass information on hunting, edible plants, survival techniques, and so on, to the next generation, except orally.  Later in the article, Ms. Wong notes that until around 30,000 years ago, neither homo sapiens nor Neanderthals lived long enough to be grandparents; around that time, homo sapiens began to live to see their grandchildren - but not Neanderthals.  Living long enough to be grandparents is a tremendous evolutionary advantage - additional help in child rearing, plus the transmission of learning and experience to the new generation.

Was it lack of the ability to pass on workable survival techniques that did in the Neanderthals?  Or was it merely those wild climate swings, themselves?  How would we cope with a climate that took an area from forest to open grassland within a generation?  How will we, if it happens to us?  The climate swings the team studied covered 40,000 years - longer than recorded human history.  We're worried about human caused climate changes (well, some of us are) - we need to remember that climate changes we didn't cause may be just as significant and just as threatening.

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