|
|||||||||||||||||||||||||||||||||||||||||||||
![]() ![]() ![]() ![]() ![]() ![]() ![]() First | Previous | Next | Last | | Index | Home Slide 59 of 109 Knowing the variation of sequences between modern humans and Neanderthals is important in determining if Neanderthals contributed to the human gene pool. However, without a measure of the variation among ancient anatomically modern humans and between them and modern humans, the data is incomplete. The first of these studies was published in 2001, examining the mtDNA sequences of 10 ancient Australians (1). A summary of the HVR-1 sequence of these individuals (compared with the modern human reference sequence, modern Aboriginal polymorphism, Neanderthals, and chimpanzees) can be found in the Table, below. The first thing that one notices is that the sequence variation of ancient humans compared to modern humans is at most 10 base pairs (in LM3, the most ancient specimen), which is nearly equal to the average variation among modern humans population groups, which is 8 base pairs. LM3, dated at 40,000 years old (redated from the original estimate of 62,000 years old, 2), varied the most from the modern human reference sequence, but this variation included only three bases shared with Neanderthal specimens. Since LM3 was a contemporary (or lived even earlier than the Neanderthals sequenced to date), it is apparent that the human genome was already nearly "modern" before Neanderthals died out. Of the ten sequence differences between LM3 and the modern human reference sequence, five of those bases correspond to polymorphisms found in modern Aboriginal people, leaving only a five base difference - certainly within the range of that found among modern humans. Overall, the lack of "evolution" for humans over the last 40,000 years stands in sharp contrast to the large differences seen between modern humans and Neanderthals. A second study examined the mtDNA sequences of two Cro-Magnon specimens dated to 23,000 and 25,000 years old (3). One specimen (Paglicci-25) had no sequence differences from the modern reference sequence, and the other (Paglicci-12) only one substitution (see table below). It is remarkable that so little change in the sequence had occurred over the last 23,000 years of human "evolution."
References
|
Last Modified June 21, 2006