London, Jan 9 (IANS) The teeth of a child who died 30,000 years ago are shedding new light on the evolution of modern humans.

They are part of the remarkably complete remains of a child found in the Abrigo do Lagar Velho, Portugal and excavated in 1998-99 under the leadership of Jo㯠Zilh㯬 professor at the University of Bristol.

Classified as a modern human with Neanderthal ancestry, the child raises controversial questions about how extensively Neanderthals and modern human groups of African descent interbred when they came into contact in Europe.

Early modern humans, whose anatomy is basically similar to that of their modern counterparts, emerged over 50,000 years ago and it has long been the common perception that little has changed in human biology since then.

When considering the biology of late archaic humans such as the Neanderthals, it is thus common to compare them with living humans and largely ignore the biology of the early modern humans who were close in time to the Neanderthals.

With this in mind, an international team, including Zilh㯬 re-analysed the dentition of the Lagar Velho child (all of its deciduous -- milk -- teeth and almost all of its permanent teeth) to see how they compared to the teeth of Neanderthals, later Pleistocene (12,000-year-old) humans and modern humans.

Employing a technique called micro-tomography which uses x-rays to create cross-sections of 3D-objects, the researchers investigated the relative stages of formation of the developing teeth and the proportions of crown enamel, dentin and pulp in the teeth.

They found that, for a given stage of development of the cheek teeth, the front teeth were relatively delayed in their degree of formation, says a University of Bristol release.

The teeth of the Lagar Velho child thus fit the pattern evident in the preceding Neanderthals, and contrast with the teeth of later Pleistocene (12,000-year-old) humans and living modern humans.

These findings were published in the Proceedings of the National Academy of Sciences.