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Archive for 27 mayo 2013

Few days ago I read a M. Hauser (2012) paper reviewing 2011 archeological production. He highlighted that archeologist are paying more and more attention on dissonances trying to exploit them as an instrument to disturb the comfort of well-established theories about ancient human behavior. This is an indispensable procedure to pioneer in archeology and other sciences and therefore must be promoted and encouraged. In this case dissonance is, as the word says, some odd sound inside a structured symphony. By confronting the normal against the odd the pattern of normality arouses or changes. This is the way science advances. But can the odd explain human behavior? Or even, can isolated facts tell us something about global events?

Last week Ch. Austin et al. (2013) in a work published online in Nature presented the results of Barium isotope analysis made on a single Neanderthal tooth recovered in Scladina cave, Belgium. The comparison of these results with other obtained from actual humans and macaques suggested that changes in the Barium content in dental histological samples is a good proxy to assess the age of weaning. The result showed a pattern similar to those from macaques abruptly separated from their mothers during infancy. So the authors speculate that probably the Scladina Neanderthal child suffered some kind of accidental event that forced weaning. The strong point of this paper is that this new technique would “allow the evaluation of hypotheses that Neanderthal young routinely weaned at later ages than Upper Palaeolithic hominins” . This hypothesis, expressed by M. Skinner (1997), was based in the wear patterns observed in 165 Neanderthal teeth (28 individuals) and 338 UP Modern human teeth (54 individuals) and has important implications in the evaluation of reproductive rate differences among both species which supported a demographic explanation for Neanderthal extinction.

Of course the authors of the paper remain prudent about the explanatory extent of this analysis. A new technique is presented and its potential is evaluated (see the great post made by K. Hinde, one of the authors). Nevertheless some critics have been expressed about the Barium isotope use, concretely M. Richards the reputed isotope analyst from the Max Planck Institute of Leipzig declared for the NY Times that “the examination of trace elements, like barium, in archaeological samples went out of use in the 1970s and ’80s, as scientists showed that bone and teeth incorporated elements from the soil they were buried in, not necessarily from a lifetime diet”.

But, in my opinion, the most important critic is not for the paper itself, but for the media cover gave to it. For example S. Perkins entitles a report in Nature News this way: “Infant tooth reveals Neanderthal breastfeeding habits”. Isn’t this too much? First the authors of the original paper say that this is an anomalous example. Second it is a SINGLE individual analyzed. Neanderthals inhabited Europe and Near East for more than 150.000 years. Important differences among Neanderthal groups’ behavior and culture have been observed across time and space. Moreover, the amount of Neanderthal fossil remains is very high and allows population analyses.

This is one important question. Don’t we tend to overgeneralize anomalous or concrete behaviors? Saying that Neanderthals made that and this, based only in isolated evidence, creates a distorted image and neglects that there were many Neanderthal behaviors. In my opinion, behind this discuss lurks the need of confrontation between species, as a whole, that is in the basis of most explanations about Neanderthal extinction.

Summing up, the isolated or even anomalous evidences have a great explanatory power if they are confronted with more general knowledge and they are necessary to shake the firmly established theories. Also, methodological advances, as this one regarding weaning age estimation, are crucial to advance in the knowledge of paleolithic human behavior. But, overgeneralization goes against the understanding of the variability and richness of the different paleolithic groups, and this is a critical aspect for archeology and evolutionary analyses. General and repeated behaviors can be confidently seen as structural behaviors (All for one!) but isolated ones cannot be extended acritically to an entire population or species (one for All?).

By Joseba Rios-Garaizar
ResearchBlogging.org

Hauser, M. (2012). Messy Data, Ordered Questions American Anthropologist, 114 (2), 184-195 DOI: 10.1111/j.1548-1433.2012.01417.x

Austin, C., Smith, T., Bradman, A., Hinde, K., Joannes-Boyau, R., Bishop, D., Hare, D., Doble, P., Eskenazi, B., & Arora, M. (2013). Barium distributions in teeth reveal early-life dietary transitions in primates Nature DOI: 10.1038/nature12169

Skinner, M. (1997). Dental Wear in Immature Late Pleistocene European Hominines Journal of Archaeological Science, 24 (8), 677-700 DOI: 10.1006/jasc.1996.0151

Perkins, S. (2013). Infant tooth reveals Neanderthal breastfeeding habits Nature DOI: 10.1038/nature.2013.13047

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