A handful of ancient human remains from Israel garnered a huge burst of media coverage this week, as claims that the finds could “rewrite the history of human evolution” were quickly followed by a backlash from the blogosphere.
Many of the initial reports were based on a Tel Aviv University press release about a paper published in The American Journal of Physical Anthropology by Israeli and Spanish scientists. The paper detailed the discovery, in Qesem Cave near Tel Aviv, of eight human teeth dating to between 200,000 and 400,000 years ago. This makes them among the oldest significant early human remains found anywhere in southwest Asia.
According to the paper, the teeth cannot be conclusively identified as belonging to a particular species of human, whether Homo sapiens— the first modern humans — Neanderthals, or other humans. But the press release and some of the articles that drew on it state that the teeth are evidence that Homo sapiens lived in the Levant as early as 400,000 years ago. This contrasts with the prevailing view of human evolution, which suggests that Homo sapiens arose in Africa roughly 200,000 years ago.
The discrepancy between the media coverage and the paper was seized upon by science bloggers Carl Zimmer and Brian Switek, who objected to the hype around the research.
Nature spoke to Avi Gopher, an archaeologist from Tel Aviv University and a co-author of the paper, about the discovery and its press coverage.
Do the teeth that you found in Qesem Cave really provide evidence that Homo sapiens did not evolve in Africa?
We don’t know. What I can say is that they definitely leave all options open. There’s been a tendency for people to get so accustomed to the “out of Africa” hypothesis that they use it exclusively and explain any finding that doesn’t fit it as evidence of yet another wave of migration out of Africa.
Were you surprised by press reports making claims that didn’t appear in your paper?
I told all the reporters I spoke to, to be very cautious what they wrote. But that’s what happens. [Gopher also defended the press release as being worded “more sharply” than the paper but that “it was not incorrect”]
But your paper clearly avoids saying the teeth came from modern humans, although it points out traits that overlap with Neanderthal characteristics. Is there enough evidence to link them with a specific species of early human?
Teeth contain a lot of information. At this point we’ve gone as far as we can on the level of basic analysis [looking at the shape and wear patterns of the teeth]. Because we wanted to preserve the teeth, we haven’t yet tried to extract DNA or, for example, to dissect the teeth to get information about diet.
What I’ve done, with Israel Hershkovitz, Ran Barkai, and my other Israeli colleagues, is compare them to a large database of early human teeth compiled by our Spanish collaborators. The best match for these teeth are those from the Skhul and Qafzeh caves in northern Israel, which date later [to between 80,000 and 120,000 years ago] and which are generally thought to be modern humans of sorts.
If we were to take your teeth out and my teeth out and put them on a table together with early human teeth, we’d find that some of our teeth are very like some of the early human teeth. There is a range of variation and no single unique trait that identifies a tooth unambiguously as modern or archaic or Neanderthal. We offer the most reasonable conclusion based on the statistical evidence: that they represent the same population as the Skhul and Qafzeh finds, thus pushing the date for that type of early man back to a much earlier time.