Scientists in the SF Bay Area have succeeded in analyzing DNA of the homo Neandertalis (Neanderthal). The remains of bones from Europe were airlifted to a lab in Walnut Creek, run by the U.S. Dept of Energy. The scientists conducting the investigation suspect that the tiny differences between homo sapiens and neandertalis, which account for no more than 1/2 of 1% of the genome, was enough to provide the characteristic differentiation between the 2 species, such as the prominent brow ridge of the neandertal and the more slender sapiens. While there is no evidence that there was any intermingling of the species, both species co-habitated until approximately 30,000 years ago.
Background links: article in wikipedia
mitochondrial DNA of the sapiens and neandertalis
Another contribution of man's altered DNA was enhanced cognitive ability, which seems to appear suddenly in the archaeological record.