🚀 go-pugleaf

In article <Bzrn4H.GMq@newcastle.ac.uk> w.p.coyne@newcastle.ac.uk writes:
 ...
>     So bearing in mind my non-expertise here is the explanation for
>the main force which is the best I think I have heard:-
>
>   Several million years ago continental drift moved the continents
>   into positions where their climate became ultra sensitive to any 
>   changes in the Earth's rotation (Milankovich cycles).  These changes
>   resulted in a regular cycle of Ice Epochs which themselves were 
>   divided into a series of ice age followed by warmer interglacial.
>   The current Ice Epoch has lasted since (I forget, maybe 1 or 2 million
>   years ago),  and it has consisted of ice ages of about 100,000 
>   years followed by interglacials of up to 10 to 12 thousand years.
...
>       It has been argued that during the long 100,000 periods humans
>   branched into different subspecies or races and some were more 
>   successful than others at specialising.  Once the climate changed 
>    again many/most of the specialist were at a disadvantage to the 
>   less specialist races and were more likely to die out.  
>        A premium was put on adaptability and it was modern humans
>    with their mental, not physical, specialisation which "won".
>    Note though that without the repeated climate changes one of the
>    less intelligent competitors would have driven them to extinction.
>> Fred Rice
>> darice@yoyo.cc.monash.edu.au   

I think this theory (nicely explained here) is mainly due to William
Calvin <wcalvin@milton.u.washington.edu>, an occasional contributor
here.  See his book, The Cerebral Symphony.

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