I have been really anticipating the following study. The first press releases came out in March and in October, I introduced it here. It seems like the paper is finally ready to be published, but we still gotta wait until PNAS puts it up on their early edition section. It should be soon but I really can’t wait any more! It is almost torturous how PNAS teases us with press releases for such a long time prior to the actual publication being released. So in the mean time, I’m gonna have to make you suffer thru an extension of my October introduction.
The study ultimately originates from Jean-Jacques Hublin, director of the Human Evolution Department at Max Planck Institute for Evolutionary Anthropology in Leipzig. But the team of co-authors are an international group who studied growth patterns in Neandertal teeth. Similar to the rings around a tree are these unique growth lines both inside and on the surfaces of teeth that can be counted to estimate age and developmental stage at death. This form of tooth analysis is called dental anthropology.
As an undergraduate, I was friends with several graduate students at my anthropology department were studying this aspect of physical anthropology. My friend Josh studied animal teeth, specifically deer teeth, from archaeological sites to estimate the time of year that hunting took place. If I remember correctly, Vicki Wedel and Chelsey Juarez have also both used this form of analysis to estimate the age of human remains found in a forensic context.
The new study applies dental anthropology in a paleoanthropological context; Neandertals were analyzed to study their growth developmental patterns in comparison to humans. In October, only four hominids were reported in the analysis the Nean dertals from Le Moustier and Krapina and the early Homo sapiens from Qafzeh and Jebel Irhoud. In a press release issued today, the Scladina Neandertal child is also included in the study.
“The Scladina juvenile, which appears to be developmentally similar to a 10-12 year old human, was estimated to be in fact about 8 years old at death… The Scladina Neanderthal grew teeth over a shorter period of time, and has more teeth erupted… than similarly-aged fossil or living humans (Homo sapiens). This suggests that other aspects of physical development were likely more rapidly achieved as well, implying significant differences in the behaviour or social organization of these ancient humans. This pattern of development appears to be intermediate between early members of our genus (e.g., Homo erectus) and living people, suggesting that the characteristically slow development and long childhood is a recent condition unique to our own species.”
So Neandertal growth and development was much more accelerated than modern day humans. Very interesting conclusion. The following two tables document standard patterns of tooth development in modern humans, they were reconstructed from pages 32, 45, and 53 of Ash & Nelson, Wheeler’s Dental Anatomy, Physiology, and Occlusion. Note, this is not a fixed pattern for all humans, but rather a compilation of average times of tooth development. For example, my third molars (wisdom) teeth were completely developed and erupting when I just turned 14. This table says the norm for wisdom tooth eruption is 17-21 years of age.
So clearly my developmental pattern was ahead of the game as far as my wisdom teeth goes. What if that was the case then for this Scladina Neandertal? What if it was like me and developed its teeth faster? This here in lies the problem with limited samples. Sure, I don’t yet have the publication to see exactly how large the sample size was, but without large numbers (n = to 100 or larger) it is hard to get an accurate representation on what’s the normal accepted values for tooth variation. I know there ain’t that many juvenile Neandertal fossils as of yet.
If Neandertals were anything like us, and the genetic, archaeological, and skeletal evidence shows they were more similar than not, surely they a lot of variation that would affect the rates of development and life history… Just something to think about before the paper comes out.
One last thing, here’s the running title and citation to the paper,
“Rapid Dental Development in a Middle Paleolithic Belgian Neanderthal”
Tanya M. Smith, Michel Toussaint, Donald J. Reid, Anthony J. Olejniczak, Jean-Jacques Hublin
Proceedings of the National Academy of Sciences USA December 2007