The retrieval of ancient DNA from two Neanderthal skeletons found at Mezmaiskaya in Russia and Feldhofer in Germany has fueled demand for more of the same. But a group of British experts has warned the science community to beware.In this week's Nature magazine (Brief Communication, Vol 410, pp771-2), the group says its calculations suggest that the DNA may have survived only because of unusually favorable circumstances -- the specimens are geologically young and the average temperature of their cave sites is low -- and that very few other Neanderthal sites could be expected to produce useful samples of DNA.
What concerns the group is that the successful retrieval of the DNA could spark a rush to analyze other Neanderthal samples, possibly to destruction.
"We recommend that any additional Neanderthal destined for destructive analysis should be carefully selected, taking into account its integrated thermal history," says the group, comprising Matthew Collins and Colin Smith, both of Newcastle University; Andrew Chamberlain of Sheffield University; Michael Riley of Birmingham University; Alan Cooper of Oxford University and Chris Stringer from the Natural History Museum in London.
The group calculated the likely deterioration of DNA for a series of fossils, less than 60,000 years old, which had been found at sites for which there was reliable climatic data. Since temperature is the critical factor, the likely rate of DNA deterioration was expressed in terms of its "thermal age."
Thermal age is defined as the number of years required, at a constant temperature of 10C, to produce the DNA degradation calculated from its thermal history.
The calculation showed that bones with a thermal age greater than that of the Feldhofer Neanderthal failed to yield DNA. When other Neanderthal sites from Northwestern Europe were subjected to the same analysis, only 9 of the 39 cave sites proved to be thermally younger than Feldhofer, and none strikingly so.
Dr. Matthew Collins of Newcastle University's Institute of Fossil Fuels and Environmental Geochemistry recently reported that proteins could survive in bones for much longer than previously believed (New Scientist 'In Brief', 06/01/01).
(Reference: Nature Vol 410, pp771-2.)
[Contact: Dr. Matthew Collins]
12-Apr-2001
