A unresolved question about evolution

[marianomanto]

Hi everybody. I am reading Jared Diamond's - Guns, germs and steel. Check this out its very cool:
In chapter "Up to the straight line", he explains how the different migration streams moved from Africa.




"Obviously, some momentous change took place in our ancestors' capabilities between about 100000 and 50000 years ago. That great leap forward poses two major unresolved questions, regarding its triggering cause and its geographic location. As for its cause, I argued for the perfection of the voice box. Others have suggested instead that a change in brain organization (...)

As for the site of the great leap forward, did it take place primarly in one geographic area, in one froup of humans, who were thereby enabled to expand and replace the former human population of other parts of the world? Or did it occur in parallel in different regions, in each of which the human populations living there today would be descendants of the populations living there before the leap? 

The rather modern-looking human sjulls from Africa around 100000 years ago have been taken to support the former view with the leap occurring specifically in Africa.
Skulls of humans living in China and Indonesia hundreds of thousands of years ago are considered by some physicial anthropologists to exhibit features still found in modern Chinese and Aboriginal Australians. If true, that finding would suggest parallel evolution and multiregional origins of modern humans, rather than origins in a single garden of Eden.

The issue remains unresolved."

What do you think? Moreover, Is this related to the concept of races?

Cheers

[Alex K]

A very intriguing book, I'm about halfway, but it is not a casual read and I keep getting distracted by other things... I haven't got an answer for you. Can you specify about what you wonder whether it has something to do with races?

[marianomanto]

Well, if the case is parallel evolution, the species would show the same general tendency (increase in brain size and standing straight), but even when we are the same species the difference between us would be reflected in the race right? Still, a coupling between different races would still result in fertile children.

Thats why I thought that maybe parallel evolution was more likely but I am no antrop. nor biologist...

[Minimalist]

Diamond is sticking to the Clovis-First model of populating the America's which has been largely discredited by recent finds.

Worse, he fails to account for the Dmanisi fossils which date back almost 2 million years and were homo erectus.

http://www.sci-news.com/othersciences/an...01474.html

Dmanisi Human: Skull from Georgia Implies All Early Homo Species were One

Traditionally, researchers have used variation among Homo fossils to define different species. But in light of these new findings, Dr Lordkipanidze and his colleagues suggest that early, diverse Homo fossils, with their origins in Africa, actually represent variation among members of a single, evolving lineage – most appropriately, Homo erectus.

[Whateverist]

The central question in the book is why do the peoples from certain lands have so much more 'cargo' than those in other lands, supposedly a question put to him by a man in New Guinea I believe.  His answer is that people living in certain zones benefit in a number of ways.  In particular, almost the only large herbivores which are suitable for domestication live there.  It isn't that Europeans or Asians were more clever to have thought of domestication; they just happen to be where the suitable animals exist.  Living with those animals subjected us to diseases to which we eventually evolved immunity but which we brought with us wherever we went as an a weapon of immense power.  Furthermore, it is easier to utilize the same plants when you move along the same latitudes, and no latitudes have as much land mass as that of eurasia (and much later, north america).  So for these an other reasons, the answer to the central question seems to be luck - not smarts.

He speculates that people who work harder for a living in more difficult climates probably demonstrate and require more intelligence than those who benefit from specialization as we do from modern farming and domesticated animals.  I don't recall much in the book about earlier hominid migrations.  But he certainly doesn't think there are any intrinsic differences in intelligence among our modern races, just the opposite really.

[Minimalist]

I remember the uproar which broke out in the late 60's when Arthur Jensen suggested that sub-saharan blacks were less intelligent because they had been "cut off" from genetic interaction with the rest of the world.  Such research has been largely discredited now but it should be noted that in spite of this alleged "isolation" the reason that blacks were brought to the new world as slaves was that the native-americans had the effrontery to keep dying in droves on their new masters from imported diseases but blacks didn't.  The New World really was "isolated" by the oceans.  There was plenty of contact between sub-saharan africa, either by caravan across the Sahara or as a result of Arab traders on the East Coast and later European explorers on the West Coast.

[marianomanto]

Diamond is sticking to the Clovis-First model of populating the America's which has been largely discredited by recent finds.

Worse, he fails to account for the Dmanisi fossils which date back almost 2 million years and were homo erectus.

http://www.sci-news.com/othersciences/an...01474.html

Dmanisi Human: Skull from Georgia Implies All Early Homo Species were One

Traditionally, researchers have used variation among Homo fossils to define different species. But in light of these new findings, Dr Lordkipanidze and his colleagues suggest that early, diverse Homo fossils, with their origins in Africa, actually represent variation among members of a single, evolving lineage – most appropriately, Homo erectus.

Thanks for the info.
And the newspaper by the way!