New Near-Neanderthals Complicate the Human Family Tree

DNA recovered from a 40,000 year old pinkie bone found in Russia’s Denisova cave links a newly-described extinct line of Neanderthal-like human ancestors to Melanesian populations of the South Pacific.

The Denisovans remain an exceedingly enigmatic branch of the human family tree. Evidence of their existence consists of two bones: the pinkie, which scientists believe was that of a girl who died around 6 years of age; and a single tooth from another individual, an adult. DNA sequencing from those samples suggests that the Denisovans separated from the Neanderthal line some 350,000 years ago, and that they passed some four to six percent of their genetic material to humans living in present-day Melanesia, according to a study published in Nature. With a previous study showing that one to four percent of of all modern human DNA can be traced to Neanderthals, the picture of humankind’s ancient past becomes complicated indeed.

Paleontologists have long suspected that populations of what seemed like difference species of Homo interbred throughout evolutionary history; the proximity of Homo sapiens and other groups over long periods of time provides powerful circumstantial evidence. But only these recent studies have offered crucial genetic confirmation of such matchings. Such evidence also calls into question the species designations of Neanderthals and a broad variety of other near-human relatives discovered in recent years�if they were truly separate species, their offspring could not have reproduced to pass on a complicated genetic heritage to the present day. It’s a reminder that the tent of human evolution is very big, with lots of room for connections to be forged over the shifting millennia. [via National Geographic]