"We're talking about humans, not trees"

3 minute read

What an excellent line from Clive Finlayson, quoted in this story about that high-mobility Neandertal tooth:

Analysis of the tooth -- part of the first and only Neanderthal remains found in Greece -- showed the ancient human to whom it belonged had spent at least part of its life away from the area where it died.

I don't really understand why Neandertal mobility is a controversial topic, although I can attest that it is one. There is no large carnivore or omnivore (and precious few large mammalian herbivores) that aren't very mobile. With this specimen, they determined the ratio of two strontium isotopes (strontium-87 to strontium-86), a ratio that differs across different geographic locations because of soil and bedrock geology. An individual picks up the distinctive strontium isotope ratio of his or her local surroundings through the food chain.

The study has been online for a while; here's the abstract:

We report here direct evidence for Neanderthal mobility through the measurement of strontium isotope ratios in tooth enamel using laser-ablation, which allows us to use much smaller samples than traditional methods. There has been a long-standing debate over the extent of Neanderthal mobility, with some arguing for Neanderthals having a very limited geographic range and others for more substantial, and even seasonal, lifetime movements. We sampled across the enamel of a Neanderthal third molar from the site of Lakonis, Greece, dating to ca. 40,000 years ago. The tooth was found in a coastal limestone cave, yet the strontium isotope values indicate the enamel was formed while the individual resided in a region with bedrock consisting of older (more radiogenic) volcanic bedrock. Therefore, this individual must have lived in a different (more radiogenic) location during this period of third molar crown formation (likely to be between the ages of 7 and 9 years) than where the tooth was found. This strontium isotope evidence therefore indicates that this Neanderthal moved over a relatively wide (i.e. at least 20km) geographical range in their lifetime.

I can see some rationale for the suggestion that Neandertals weren't very mobile in this context -- for example, they didn't transport shellfish very far inland. Starting from a tooth at a coastal site, you might hypothesize that most of its diet had been local. But there is abundant evidence from other sources that they moved a lot. I wrote about this last year, citing work by Slimak and Giraud that shows transport distances of more than 250 km for some Mousterian artifacts from Champ Grand. Recent hunter-gatherers historically have had very large home ranges, with occasional travel over much longer distances, and a high rate of intermarriage between groups. All of these things can result in people dying at some distance from the place where they grew up.

So I would be amazed if Neandertals weren't mobile enough for an individual to die 20 km from his or her birthplace. I suppose the quote indicates that Clive Finlayson would be surprised, too:

"The technique is interesting, and if we could repeat this over and over for lots of (individuals) then we might get some kind of picture," he said.
"(But) I would have been surprised if Neanderthals didn't move at least 20 kilometers (12.5 miles) in their lifetime, or even in a year ... We're talking about humans, not trees."

Still we shouldn't minimize the result, which really is constrained by the limits on this kind of data. The authors report just a minimum for this individual -- all they are claiming is that the individual's strontium ratio is inconsistent with the local geology, and there is no consistent geology within 20 km. The individual may have come from much further; we cannot say.

In that context, I would suggest that this study is a test of the idea that coastal resources were not used exclusively by coastal-living Neandertals, but that instead wide-ranging groups of Neandertals used coastal resources when they were at the coast. This was the hypothesis advanced by Mary Stiner in her Honor Among Thieves, which documented coastal resource use in the Italian Mousterian.

Maybe it's not too profound, but I think it's an important point to limit the naive interpretation that coastal sites were occupied by "culturally different" groups of Neandertals, or that Neandertals were somehow not behaviorally flexible enough to master the use of different resource bases.