December 13, 2011

Of Elephants and Men

The same team described dental remains from Qesem cave.

The press release:
The elephant, a huge package of food that is easy to hunt, disappeared from the Middle East 400,000 years ago -- an event that must have imposed considerable nutritional stress on Homo erectus. Working with Prof. Israel Hershkovitz of TAU's Sackler Faculty of Medicine, the researchers connected this evidence about diet with other cultural and anatomical clues and concluded that the new hominids recently discovered at Qesem Cave in Israel -- who had to be more agile and knowledgeable to satisfy their dietary needs with smaller and faster prey -- took over the Middle Eastern landscape and eventually replaced Homo erectus.

The findings, which have been reported in the journal PLoS One, suggest that the disappearance of elephants 400,000 years ago was the reason that modern humans first appeared in the Middle East. In Africa, elephants disappeared from archaeological sites and Homo sapiens emerged much later -- only 200,000 years ago.
It would be useful to get something more substantial than teeth to estimate the presence of a new hominin lineage as proposed by the authors. In their earlier work they noted some Neandertal traits in their teeth sample, although, on balance, they linked the Qesem pre-200ka teeth with the much later modern humans from the Levant. The 400ka date is (roughly) when geneticists tell us modern humans and Neandertals had already began to diverge genetically.

Neandertal-like traits have been noted in European hominins (such as Atapuerca) well in advance of this age. A priori, the idea that the common ancestor of modern humans and Neandertals lived in the Near East seems attractive to me, since that is the area where the demarcation line between the two species appears to have been. While the authors' theory about the disappearance of elephants and the emergence of the Acheulo-Yabrudian merits attention, I don't think the evidence for it is strong enough yet.

PLoS ONE 6(12): e28689. doi:10.1371/journal.pone.0028689

Man the Fat Hunter: The Demise of Homo erectus and the Emergence of a New Hominin Lineage in the Middle Pleistocene (ca. 400 kyr) Levant

Miki Ben-Dor et al.

The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex – the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins. Qesem Cave thus provides a rare opportunity to study the mechanisms that underlie the emergence of our post-erectus ancestors, the fat hunters.


1 comment:

Maju said...

"The same team described dental remains from Qesem cave".

Both papers are quite bad: way too much speculation and way too few facts.