Meet the Neanderthals

Neanderthal child (model reconstruction: E. Daynčs, Paris)

By BBC News Online's Helen Briggs

Reconstructions of Neanderthal skulls add to growing evidence that the creatures were not close relatives of modern humans.

The distinctive features of the Neanderthal skull were established in early infancy - possibly even in the womb - say researchers in Switzerland.

Most of what makes a Neanderthal and what makes a modern human is already present in the infant

Christoph Zollikofer, University of Zürich

Their conclusion is based on sophisticated computer graphics charting the cranial development of Neanderthals, from babyhood to adult life.

The findings support the idea that Neanderthals did not interbreed with early modern humans and contributed little or nothing to the present human gene pool.

'Sister' species

Christoph Zollikofer and Marcia Ponce de León of the University of Zürich used fossils to construct 3D virtual computer images of the skulls of Neanderthals and early modern humans.

Physical differences in skull development - such as the Neanderthal's receding chin and low, sloping forehead - were fixed by the age of two years, said Dr Zollikofer.

A modern human child (left) and a Neanderthal child (right)

"Most of what makes a Neanderthal and what makes a modern human is already present in the infant," he told BBC News Online.

This suggests that Neanderthals were a separate "sister" species from modern humans.

"We don't see any evidence of gene mixing at all," he said. "But we can't prove this."

Mysterious demise

Neanderthals were an ancient group of hominids that lived in Europe, the Near East, Central Asia, and probably western Siberia more than 100,000 years ago.

Their mysterious demise about 30,000 years ago has been the subject of much debate and speculation.

Some believe that the Neanderthals were killed off by a new type of human, which began to take over their hunting grounds during the middle of the last Ice Age.

Another theory is that the Neanderthals disappeared through interbreeding with humans.

Recent DNA analysis of three Neanderthal skeletons suggests that they were not our ancestors but a sidebranch of human evolution.

The Swiss research, published in the scientific journal Nature, seems to support that view.

Modelling the soft tissue

Virtual and stereolithographic reconstructions of a Neanderthal child

Clinical CT and MRI data (left) were used to construct the face of an adolescent Neanderthal

All images copyright M Ponce de León and Ch Zollikofer, MultiMedia Lab, University of Zurich.