"Bottle-neck" in human population 70,00 years ago

[richardb]

After watching Six Feet Under, my wife and I were too lazy to get off the couch and started channel-surfing. We came upon a science channel program on Super Volcanos.

The basic premise of the show (though not of my question) is that all of Yellowstone National Park is basically the top of a super volcano that seems to go off every 600-800 thousand years… and the last eruption was 600,000 years ago!

As part of their various evidence (all of which was absolutely fascinating, BTW, especially the thermal satellite pictures), they told of evidence that there was a bottleneck in the human population about 70 - 80 thousand years ago. Their evidence was that of standard mitocondrial DNA mutation. I did not follow everything exactly and I may be getting parts of this mixed up in my explanation, but I think the idea was that there is a standard rate of mutation in mitocondrial DNA, but the current human DNA proves there was a “bottleneck” in this standard, graphable, trackable mutation that proves that 70 to 80 thousand years ago, the human population was somehow devastated or wiped out or reduced to the extent that there was left only 5 to ten thousand people, and that all of todays population are directly descended from those 5 or 10 thousand people. If this was not the case, the genetic differences in humans today would be much greater (or something like that).

The show goes on to talk of a documented super volcano that erupted 74,000 years ago (and suggests that this may have been the cause for the human bottleneck).

Here’s my question: (finally)

If there was such a bottleneck where 70,000 years ago the human population was reduced to 5 or 10 thousand people, just how many people were there before the catastrophic event?

What kind of people/civilizations were there 70,000 years ago? Off the top of my head, I’m thinking that recorded history only goes back maybe 5 or 10 thousand years, if that much. WTF was there 70,000 years ago? Were there just “cave men” or was there some kind of actual civilization?

Just curious.

Of course, if anyone else saw this program and would like to correct or add to anything I have said, please go right ahead.

[scm1001]

I think this was the programme http://millennium-debate.org/ind3fe2.htm

One has got to be a little careful. There is still alot of work to do on genetic varaition to pin down how long ago one can place comon ancestors, and the variability in the data is quite wide. Nevertheless, it is an accepted theory that people emigrated out of africa 200,000-50,000 ago, probably in several waves. At that time we would have been hunter-gatherers, with some implements, perhaps spears, living in caves and crude shelters. No civilisation, probably no musical instruments and no writing, possibly no complex language.

As to how many is a guess. There were probably 100,000s of hominids around that time, but most populations became extinct according to the bottleneck theory

[Exapno_Mapcase]

Just so that other people can view the data, so to speak, the transcript for the BBC show, originally aired in 2000, you’re talking about is available here. (People who don’t want to scroll can find the whole mitochondrial section excerpted here.

Harpending, who is quoted on the subject, has somewhat modified the claim of a bottleneck 74,000 years ago and has moved it to about 40,000 years ago, as shown in this 2002 article. The bottleneck may better explain the demise of the Neandertals than homo sapiens. But the whole notion of the Toba supervolcano 74,000 years ago knocking out humanity seems to have vanished.

There’s always been tension between the geneticists who look at mitochondrial evidence and the field anthropologists who look at bones and sites. This is compounded by the tensions between the Out of Africa and the Multiregional divide in the field. I’m no expert, but I find the notion of homo sapiens worldwide being reduced to a few thousand people to be highly suspect.

[sunfish]

@Exapno Mapcase

But the whole notion of the Toba supervolcano 74,000 years ago knocking out humanity seems to have vanished.

With good reason. One of the troubling things about that disaster scenario was its selectivity - you would have expected a “global catastrophe” to push many species toward the brink of extinction, with resultant genetic bottlenecks. However, there’s no evidence for any such bottleneck in other species that were around at the same time. It’s rather odd that omnivorous humans, in a better position than many other creatures to survive major losses in food supplies, would be the only species affected.

A comment published last fall underscores this point:

If the putative Toba induced volcanic winter resulted in an environmental catastrophe strong enough to cause a bottleneck in a species as resourceful and adaptable as modern humans, one would expect that other, more environmentally sensitive taxa (with more specialised ecological requirements) would have suffered at least a similar population crash and that many would have become extinct. It appears that there has been no mammal extinction associated with Toba (A. Currant pers. com.), and [Erwin and Vogel, 1992] examined the hypothesis that super-eruptions (including that of Toba) have caused mass extinctions and found no evidence for this.

Gathorne-Hardy, F.J., and Harcourt-Smith, W.E.H., 2003, The super-eruption of Toba, did it cause a human bottleneck? Journal of Human Evolution 45:227-230.

[Exapno_Mapcase]

Good points, sunfish.

There’s a general principle involved here. Unfortunately, it’s:

Never get your scientific information from a TV documentary.

The corollary is:

Never get any other type of information from a TV documentary either.