Wednesday, September 12, 2007

Clean-toothed Neanderthals

In case you haven't heard, two Neanderthal molars were recovered at the ca. 68.4 kya Spanish site of Pinilla del Valle, near Madrid. While finding any Neanderthal remains is always good news to me, the spin taken on those two (and, presumably, the reason which such a comparatively small find wound up being news on Reuters and El País) is that they display grooves that have interpreted as evidence for habitual toopicking. Martín Cagliani and John Hawks have already mentioned a 2003 paper by L. Hlusko to make the point that this discovery should come as no surprise since there is suggestive evidence of toothpicking going back to about 1.8 mya (on the Omo L 894-1 RP3 specimen).

I agree with them that the discovery as such should come as no surprise. However, I'd alo like to point out another CA paper on the topic of toothpicking,- this one by Agger et al. (2004), which has a set of altogether different implications. Agger et al. (2004:403)) argue "that toothpicking behavior may represent indirect evidence for the evolution of the biological capacity for language." Briefly, this is due to the presence of cranial nerve V, the largest branch of which controls (among other things) lingual movement and makes the teeth and gums extremely sensitive to various irritants. And toothpicking is one way to remove small irritants lodged between the teeth and/or in the gum. They conclude that:

"As anyone who has had small pieces of food caught between his or her teeth or has developed a tooth chip is aware, such occurrences cause a sensation out of proportion to the size of the food matter or tooth defect. This exquisitely sensitive neural pathway for conveying proprioceptive information to higher brain centers can only be routed via a developed and functioning cranial nerve V. As a result, oral dental sensations promote the obligatory postprandial toothpick, at least in modern times and plausibly in early hominids. The proprioceptive information is not only protective but critical feedback for the tongue posturing necessary for speech.

Thus it appears that both a highly developed afferent cranial nerve V (trigeminal nerve) and VIII (auditory nerve) are needed for input to the Broadman's area along the perisylvian fissure of the human brain, the region of the brain that is critical for the formulation of speech. We hypothesize that the ability to sense and remove food particles between teeth occurred approximately 2 million years ago as a result of selective pressures driving the evolution of complex vocalization of the hominid frontal-parietal lobe." (Agger et al. 2004: 403).

So, if Agger et al. are correct, the Pinilla del Valle discovery might imply not only that Neanderthals could and did practice some form of dental hygiene, but also - and perhaps mostly importantly - that they had the capacity for speech, as is also suggested by the presence of an essentially modern hyoid bone in the Neanderthal larynx (Arensburg et al. 1989).


Agger, W. A., T. L. McAndrews, and J. A. Hlaudy. 2004. On Toothpicking in Early Hominids. Current Anthropology 45:403-404.

Arensburg, B., A. M. Tillier, B. Vandermeersch, H. Duday, L. A. Schepartz, and Y. Rak. 1989. A Middle Palaeolithic Human Hyoid Bone". Nature (338): 758-760.

Hlusko, L. J. 2003. The Oldest Hominid Habit? Experimental Evidence for Toothpicking with Grass Stalks. Current Anthropology 44: 738-741.


archaeozoo said...

If that is the case, then it is a very intriguing notion as I believe there has been debate for some time now as to when speech evolved.

Julien Riel-Salvatore said...

Hi Archaeozoo,
thanks for your comment!

I agree with you: it is a very intriguing notion, and there has indeed been a lot of debate about when the capacity for modern language evolved. I thought that the Agger et al. paper put an interesting spin on the potential implications of this discovery, so I wanted to mention it. As for whether Neanderthals had fully modern speech, well, we have the neural set-up, the laryngeal set-up, the brain capacity, evidence for altruistic social behavior, evidence of complex technological tasks, all of which combine to suggest to me that it is very likely that Neanderthals had something very much like modern speech.

Of course, detractors will suggest otherwise - before the Kebara hyoid was found, it was assumed they didn't have the morphology - afterwards, it was argued it didn't necessarily mean anything since pigs have hyoids similar to humans' (if I remember correctly). Now, all the talk is about genes like FOXP2 and the like, but we really don't know.

I'm not aware that there has been any debate over the Agger et al. paper or any refutation of the arguments they proposed. This is why I felt it might spur some good discussion to bring it up in light of this recent discovery, precisely given how contentious the debate over the linguistic capacities of Neanderthals can get!

Tim said...

Very interesting post Julien, I'd never have made a connection between tooth-picking and language, thanks for the link.