July 16, 2012

The theory that won't die: Chris Stringer on Modern Human Origins

I devoted a whole post on the topic recently, so I won't repeat myself. I'll just say that if modern human behavior evolved in Africa and it was this which facilitated the spread of humans into Eurasia ~60,000 years ago, then they forgot to leave behind any evidence for it.

A Bone Here, a Bead There: On the Trail of Human Origins
There were remarkable things happening in Europe at least 40,000 years ago, with the painted caves, with flutes, with the statuettes and so on. But the seeds of that revolution were sown in Africa more than 100,000 years ago. I would argue that when modern humans came out of Africa, say 60,000 years ago, fundamentally they were behaviorally modern. They took that into Europe. They took that into Asia and into Australia. So there was no single revolutionary event in Europe; this was something that was in modern humans when they came out of Africa, and the ones who stayed behind as well.
The following quote by mousterian is worth highlighting:
What we are dancing around here is an issue more fundamental than simply coastal vs. interior, early vs. late. If it was an expansion (or wave of expansions) during MIS 5 through the interior, these are hunter-gatherers tracking a known ecosystem. If a late expansion during MIS 4 or early MIS 3 along the coast, these represents some innovative cultural adaptation that has enabled them to exploit a new ecosystem and rapidly disperse through it (i.e. the rim of the Indian Ocean). In other words, were we lucky hunter-gatherers in the right place at the right time during the Last Interglacial, or crafty beachcombers struggling for survival across the post-apocalyptic post-Toba landscape? Pushed out of Africa, or pulled into Arabia? In my mind, this is the real disparity between the two models.

Interestingly, all of the Palaeolithic archaeologists working in Arabia unanimously agree on the "lucky hunter-gatherers" MIS 5 scenario. Granted, it’s not as sexy as believing we are somehow fundamentally different, new, and improved. That’s the problem with fact versus fiction.
My chips are on the "lucky hunter-gatherers" MIS 5 scenario and I'm sticking to it until I see any evidence for behaviorally modern people in East Africa or Arabia or the Levant at the time of the postulated 60ky-old migration. But, it's good to see both positions vigorously argued.

7 comments:

andrew said...

The notion that is making increasing sense to me, based on comments in the same thread and some thought about whether they make sense, is that the jungles of Burma and SE Asia may have been just as formidable barriers to folk migrations from India of the whole peoples necessary to have population genetic effects (as opposed to a few stray explorers or traders), much as the Congo jungle did in Africa.

The ash fall from the Toba erruption of 75,000 years ago, give or take, would have been heaviest right where these jungles are thickest in this region. Toba may have briefly killed off the jungles, allowed modern humans bottled up in India a brief window of migration into the rest of Asia until the jungle grew back, possibly less than a century later, reinstating a barrier to gene exchange that would leave a clear mark all the way up to the present thereafter.

terryt said...

"Toba may have briefly killed off the jungles, allowed modern humans bottled up in India a brief window of migration into the rest of Asia until the jungle grew back, possibly less than a century later, reinstating a barrier to gene exchange that would leave a clear mark all the way up to the present thereafter".

Perhaps the expansion into SE Asia coincides with the Toba eruption, but I suspect Toba's influence was less than usually supposed.

"the jungles of Burma and SE Asia may have been just as formidable barriers to folk migrations from India of the whole peoples necessary to have population genetic effects (as opposed to a few stray explorers or traders), much as the Congo jungle did in Africa".

As I have long suggested. Recently I looked at a vegetation map of Southern Asia in a 1982 Readers' Digest Atlas that I bought about a year ago. I suddenly realised that the most probable reason for mt-DNA M's rapid diversification is that they were quite possibly the first humans of any kind to enter the heavily forested hill country that stretches between northeast India and northern Thailand. Such country includes northern Laos, north Vietnam, Yunnan and much of Burma. That idea would account for both the absence of ancient human fossils through much of the region and for M's rapid expansion and diversification.

N's much lesser basal diversity may be a result of N having moved through regions already occupied by 'ancient' humans. Y-DNA C's similarly small basal diversity mirrors that of mt-DNA N, while K's huge diversity mirrors that of mt-DNA M.

But both N and C were eventually able to enter the previously unoccupied regions of Australia and Japan. M and K's descendants also entered both regions but to me it looks very much as though they were later arrivals.

Michael Russell said...

In an earlier Dienekes post, we saw that the Australian Aborigines permanently split away from their ancestors c. 62-75 kya.
This seems to me to be important in theories of the emergence of modern human behaviour: If our view is that
(1) modern human behaviour was obtained in only one area at certain time, by some confluence of genetics and social factors, and
(2) this behaviour (with associated genetics) then spread across the world by genetic/social diffusion,

then proposals that modern human behaviour emerged as late as 60000 years ago lead to the worrysome conclusion that the Australian Aborigines might not be counted as human.... if they split from their ancestors too early to have picked up the relevant genetic and social diffusion-package.

Is this or similar criticism implied, Dienekes, when you briefly mention Australian Aborigines in your post?

Dienekes said...

All modern humans are behaviorally modern. Also, aboriginal Australians were not isolated for that long a time.

eurologist said...

Yes, the "jungles" had a very important impact on mobility, as did Toba.

That's why humanity split pre-Toba, and only partially re-united thereafter.

Andrew Oh-Willeke said...

"As I have long suggested."

The ideas didn't really hit me until I read it in a comment here, I think, one of yours.

"I suspect Toba's influence was less than usually supposed."

A "kill the jungles for a few years opening the door to the rest of Asia for people who are ready in India" theory is far more subtle than many allegations of Toba on modern human migration, in addition to being more tailored to the geography of its impact.

terryt said...

"proposals that modern human behaviour emerged as late as 60000 years ago lead to the worrysome conclusion that the Australian Aborigines might not be counted as human.... if they split from their ancestors too early to have picked up the relevant genetic and social diffusion-package".

I have often pointed out that is a problem for recent OoA supporters. As to the last point: we do know that Australian Aborigines did not have an Upper Paleolithic technology, so they didn't pick up the relevant 'social diffusion-package'.

"Also, aboriginal Australians were not isolated for that long a time".

I think that is true. Aborigines had certainly arrived in Australia by 45,000 years ago though, and possibly 10,000 years before that.

"The ideas didn't really hit me until I read it in a comment here, I think, one of yours".

I think I made the comment at your blog actually. I agree that your Toba theory 'is far more subtle than many allegations of Toba on modern human migration, in addition to being more tailored to the geography of its impact'.