used phylogenetic tree reconstruction -- a method that uses mitochondrial DNA to place individual groups in relative relationship -- to check the results of their pair-wise DNA comparisons. The trees show that the Neandertal sequence branches before the divergence of the various human mitochondrial DNA lineages, but after the split from chimpanzees.This phylogenetic tree also shows that the first three branches of humans are of African origin, with only the fourth branch showing non-African sequences."The branching pattern indicates that the ancestor of the mitochondrial DNA gene pool of contemporary humans lived in Africa," says Stoneking of Penn State.The researchers are confident with their results, but they caution that they are derived from only one individual. They also warn that DNA may be difficult to extract from other specimens. While the results indicate that Neandertals did not contribute mitochondrial DNA to modern humans, it is still possible that they contributed other genes.**aem**EDITORS: For more information or interviews, contact A'ndrea Elyse Messer, science and research information officer, at (814) 865-9481 (office); 867-1774 (home) or at aem1@psu.edu by email.Contact:A'ndrea Elyse Messer (814) 865-9481 (o) (814) 867-1774 (h) aem1@psu.eduVicki Fong 814-865-9481 (o) 814-238-1221 (h) vyf1@psu.edu...
