Neanderthals and Humans: No Kissing Cousins?

May 5, 2008 -- A new, simplified family tree of humanity has dealt a blow to those who contend that the enigmatic hominids known as Neanderthals intermingled with our forebears.

Neanderthals were a separate species to Homo sapiens, as anatomically modern humans are known, rather than offshoots of the same species, the new organigram published Sunday by the journal Nature declares.

The method, invented by evolutionary analysts in Argentina, marks a break with the conventional technique by which anthropologists chart the twists and turns of the human odyssey.

That technique typically divides the genus Homo into various classifications according to the shape of key facial features -- "flat-faced," "protruding-faced" and so on.

Reconciling these diverse classifications from a tiny number of specimens spanning millions of years has led to lots of claims and counter-claims, as well as much confusion in the general public, about how we came to be here.

Various species of Homo have been put up for the crown of being our direct ancestor, only to find themselves dismissed by critics as failed branches of the Homo tree.

The authors of the new study, led by Rolando Gonzalez-Jose at the Patagonian National Center at Puerto Madryn, Argentina, say the problem with the conventional method is that, under evolution, facial traits do not appear out of the blue but result from continuous change.

So the arrival of a specimen that has some relatively minor change of feature as compared to others should not be automatically held up as representing a new species, they argue.

The team goes back over the same well-known set of specimens, but uses a different approach to analyze it, focusing in particular on a set of fundamental yet long-term changes in skull shape.