November 15, 2006

scientists react to news of the neanderthal genome sequence to be published in Nature

American scientists have today published the results of a study conducted on DNA extracted from the thigh bone of a Neanderthal man who lived 38,000 years ago.

Dr Mark Thomas, Senior Lecturer in Human Genetics, UCL, said:

“The study is a very big leap in the right direction although to look at the really interesting questions about human and Neanderthal evolution, even more data will be needed. The authors hint strongly that this is exactly what they are doing. Two particularly interesting things that come out of this study are that:

1. It suggests that at the time when humans and Neanderthals split, around half a million years ago, the population size was small (less than 12,00 individuals Worldwide.

2. Their is a feint suggestion from the DNA that while Neanderthals did not spread their genes into the human species, humans may have spread their genes into the Neanderthal species at some period in the last 100,000 years.”

Fred Spoor, Professor of Evolutionary Anatomy, UCL, said:

“Identifying how the nuclear genomes of Neanderthals and modern humans compare will eventually show palaeontologists the genetic basis of the important differences in skull and body build between us and our closest biological relative. However, it is clear that the technical advances in sequencing ancient DNA are way ahead of our understanding of how genes affect large scale morphology. We obtain the script, but will need time to figure out how to read it.”

Professor Alan Cooper, Australian Research Council Federation Fellow at the Australian Centre for Ancient DNA, University of Adelaide, Australia, said:

“This work represents a major step forward in the study of our closest relatives, and promises to provide information that will allow identification of the critical changes that took place along the human evolutionary lineage, and produced the human species. The current study is limited by the difficulty that only one Neandertal specimen could be found which was not seriously contaminated with modern human DNA, and that the damage in the Neandertal sequences meant they could not be used in isolation. However the approach will be improved and applied to many more specimens, and we will soon be able to analyse Neandertal genomic organisation and variation.”

Professor Chris Stringer FRS, Research Leader in Human Origins and Director of AHOB, Dept of Palaeontology, The Natural History Museum, London, said:

“Using a particularly well-preserved fossil from Croatia and massive improvements in analytical techniques and computing power, two international teams of scientists have reconstructed significant portions of the nuclear genome of a Neanderthal for the first time, an achievement that seemed impossible even ten years ago. The results confirm the distinctiveness of the Neanderthals, and support estimates from mitochondrial DNA of a divergence time of about 500,000 years for their lineage and ours. This estimate also matches with the observation of Neanderthal features in European fossils from at least 400,000 years ago.

“But this research also promises breakthroughs in our understanding of their whole biology. Portions of DNA have already been recognised that originated from the Y-chromosome of the Neanderthal sampled, indicating it was a male individual, and this will provide valuable information for comparison with the extensive data from modern human Y-chromosomes that indicate a recent African origin for our species.

“Research can now extend to complete the whole genome of a Neanderthal and to examine Neanderthal variation through time and space to compare with ours. Having such rich data holds the promise of looking for the equivalent genes in Neanderthals that code for specific features in modern humans e.g. eye colour, skin and hair type, cognitive and language skills etc. It will be especially interesting to look for the microcephalin gene (a gene that contributes to the form of the brain) in Neanderthals, as it has recently been suggested that a variant of this gene was introduced into Homo sapiens quite recently from a distinct source, perhaps through interbreeding with Neanderthals.

“Having a Neanderthal genome will also throw light on our own evolution, by allowing a three-way comparison of the genetic blueprints that produced Neanderthals, and that today produce us and our closest living relatives, the chimpanzees. We should then be able to pin down unique changes in each genome to show how we came to be different from each other.”