Was Toba really so bad?

There's an interesting article at New Scientist about what is possibly the most crucial issue of human prehistory: the Toba supervolcano explosion, which happened some 74,000 years ago.

There are two parallel debates: how catastrophic was Toba and were humans (H. sapiens) already in southern Asia then. They converge at the point on how could they survive the consequences of the supervolcano.

The debate seems to be quite hot and multifaceted: for some the catastrophe was really bad while for others only half that bad, for some humans were already in South Asia as evidenced by the toolkits so similar to African ones while others guided by the dubious molecular clock approaches prefer to consider a post-Toba out of Africa migration and yet others would push the dates of the migration back to c. 125,000 years ago, right at the Abbassia Pluvial, when there's abundant evidence also of H. sapiens in North Africa and Palestine.

A lot of information and synthesis of the various viewpoints can be found in the abstracts of the Oxford conference titled "The Toba Super-Eruption: A critical moment in human evolution?", which are freely downloadable as PDF.

New research may reinforce human continuity through the Toba event in India

Found first via Anthropology.net but ratified and complemented through search engines on my own.

The international archaeological team lead by Michael Petraglia, Ravi Korisettar and J.N. Pal, seem to be on the path of reinforcing with hard data the theory that humankind would have survived in India through the Toba supervolcano event, c. 74,000 years ago, as reported by Oxford University.

No human remains seem to have been found yet but the data on lithic tools and the remains of other animal species all point to continuity and not the massive destruction that the thick ash layer would have suggested.

All this suggests that the ancestors of Eurasians (and by extension also the native peoples of Oceania and America) were alive and kicking at least 74,000 years ago in India, more than 15,000 years before that the often misleading "genetic clocks" tend to suggest.

In the words of Michael Petraglia:

This exciting new information questions the idea that the Toba super-eruption caused a worldwide environmental catastrophe. That is not to say that there were no ecological effects. We do have evidence that the ash temporarily disrupted vegetative communities and it certainly choked and polluted some fresh water sources, probably causing harm to wildlife and maybe even humans.

See also:
· Petraglia's team website.
· M. Petraglia et al., Middle Paleolithic Assemblages from the Indian Subcontinent Before and After the Toba Super-Eruption. Science 2007.
· James B. Harrod, Synopsis of Paleo-India. OriginsNet.org, 2007 (PDF).

Aterian and the coastal migration model

It seems that Aterian, the North African paleolithic culture (attributable to Homo sapiens), occupies the whole range of dates between c. 85,000 BP to the Epipaleolithic, when new waves (Iberomaurusian, Capsian) may have arrived from Spain and Sudan.

Recently these findings have been confirmed by archaeological research at Taforalt, Morocco, that have yielded some of the oldest known ornaments, competing for that title with Skuhl cave (Palestine) and Oued Djebanna (Algeria).

Aterian tools

Fine so far. But there is a problem: the deepest genetic layer in North Africa seems to be mtDNA haplogroup U6, that is related with other U clades of West, Central and South Eurasia. This clade is believed to have arrived to North Africa with the earliest human colonists, much like its "sisters" U5 and U8a seem to have arrived to Europe too. But, while European early sapiens colonization may date to 48-40,000 BP, not being in contradiction with the mainstream model of colonization of Eurasia from a single out of Africa migration c. 75-60,000 BP, the Aterian very old C14 dates do.

And there is nothing between Aterian and the Epipaleolithic that can explain that.

So I am starting to question the coastal migration model too, or at least the dates attributed to it.

No hardcore conclussions yet but what if... the OOA event happened much earlier, maybe c. 120,000 BP, and had a westward branch via the Levant that ended up in North Africa? There are certainly H. sapiens remains in the Levant that are date c. 100,000 BP (though they are believed to have been replaced by Neanderthals, that are dated to c. 60,000 BP).

In South Asia (key area for Eurasian prehistory) archaeology can hardly differentiate between pre-sapiens and sapiens technologies. The divide between Middle and Upper UP is placed, somewhat arbitrarily, at c. 30,000 BP (much later than in Central and West Eurasia) and human or hominin remains are very scarce anyhow. But, like in West Asia, disconinued blade tools (preluding UP somewhat) are occasionally found with much older dates. In West Asia this was (more or less consistently) attributed to Neanderthals but it is very unlikely that the findings of India can be attributed to them too.

Check for instance Petraglia et al., 2007: Middle Paleolithic Assemblages from the Indian Subcontinent Before and After the Toba Super-Eruption:

We provide here firm chronological evidence that hominins were present in the Jurreru River valley, south India, immediately before and after the YTT eruption. Analyses of the archaeological industries recovered from the site indicate a strong element of technological continuity between the pre- and post-Toba assemblages. Together with the presence of faceted unidirectional and bidirectional bladelike core technology, these pre- and post-Toba industries suggest closer affinities to African Middle Stone Age traditions (such as Howieson's Poort) than to contemporaneous Eurasian Middle Paleolithic ones that are typically based on discoidal and Levallois techniques (Fig. 3). The coincidence of (i) evidence of hominins flexible enough to exhibit continuity through a major eruptive event, (ii) technology more similar to the Middle Stone Age than the Middle Paleolithic, and (iii) overlap of the Jwalapuram artifact ages with the earlier end of the most commonly cited genetic coalescence dates (21–23) may suggest the presence of modern humans in India at the time of the YTT event. This interpretation would be consistent with a southern route of dispersal of modern humans from the Horn of Africa (24); the latter, however, will remain speculative until other Middle Paleolithic sites in the Indian subcontinent and Arabian Peninsula (25) are excavated and dated.

Jwalapuram tools

And also:
- Modern Human Origins and the Evolution of Behavior in the Later Pleistocene Record of South Asia, by Hanna V.A. James and Michael D. Petraglia, 2005 (no link found).
- J.B. Harrod, Synopsis of the Paleolithic of India (PDF).

From this last paper (a list of Indian Paleolithic sites with brief descriptions), I specially noticed two sites from before the Toba event that show blade creation. One (Hokra 1-a and Gurha, Thar Desert, Rajasthan) is not dated but the other (Patpara, Middle Son Valley) has a C14 date of at least 100,000 BP. Blade based tools are also found after the Toba event in several sites that may be dated since c. 45,000 BP.

But even if the earlier blade industries are not really consolidated UP (like happens with Levantine Jabroudian, where stone blades were made long before UP apparently by Neanderthals without continuity), presence of anatomically modern humans does not need to be related to them anyhow (in fact that is the case in may other parts of the World). And the technoligical continuity in India an the very early dates of Sapiens-made Aterian in North Africa, strongly suggest an out-of-Africa event much earlier than Toba eruption. Maybe c. 100,000 BP. There was a warm peak (a more favorable climate probably) c. 105,000 BP that could account for such migration maybe.