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Paleontology

Neanderthals Not our Ancestors

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© Courtesy of G. Focant, M.R.W.

Right profile of the external mandible found in the Scladina cave.


 

Catherine Hänni and Ludovic Orlando of the Laboratory of Paleogenetics and Molecular Evolution (LBMC)1 recently achieved the extraordinary feat of obtaining a DNA sequence from a 100,000 year-old specimen.2 The sequence consists of 123 base pairs of the mitochondrial DNA of a 10 to 12-year-old Neanderthal child, whose remains were recently excavated from the Scladina cave in Belgium. One of the reasons why this specimen was used is because it was discovered very recently, so the few individuals who were in contact with it could be identified and genotyped, excluding any possible sample contamination. The DNA was extracted from a tooth, amplified by PCR, and sequenced.

This sequence is the oldest Neanderthal DNA sequence ever reported, and is the only one that predates the probable cohabitation of Neanderthals and modern man. Indeed, all the other available sequences are from Neanderthals living in Europe only 30,000 to 40,000 years ago, during the period when modern man appeared on the continent. There are two explanations for the subsequent and abrupt disappearance of Neanderthals

from Europe: either they were displaced–or replaced–by modern man and became extinct; or they interbred with modern man, leaving just one species–us. Comparisons of mitochondrial DNA sequences from Neanderthals and modern man can help discriminate between these two hypotheses.

The 100,000 year-old sequence reported by Catherine Hänni and her team diverges somewhat from the other and more recent Neanderthal sequences. This indicates that the genetic diversity of Neanderthals was broader than previously suspected. Nevertheless, all the Neanderthal sequences, including the 100,000 year-old sequence, are more similar to each other than they are to those of modern man, whether European, Asian, or Amerindian. Similarly, all sequences from modern man are more similar to each other than to any Neanderthal sequence. There is therefore no evidence that Neanderthals were our ancestors, but rather that they were an independent species that disappeared by replacement rather than through interbreeding.

 

Alex Edelman

 

Notes :

1. Laboratoire de biologie moléculaire de la cellule (LBMC) (CNRS / Ecole Normale Supérieure de Lyon joint lab).
2. Orlando et al., “Revisiting Neandertal diversity with a 100,000 year old mtDNA sequence,” Current Biology. 16 (11): R400-2. 2006.

Contacts :

Catherine Hänni
LBMC, Lyon.
Catherine.Hanni@ens-lyon.fr


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