How Neanderthals' teeth grew
AMONG ANTHROPOID primates there is a close relationship between brain growth and tooth eruption.
Neanderthals, predecessors of modern humans, who first appeared in Europe approximately 200,000 years ago and became extinct about 25,000 years ago, have always been considered genetically closer to us than any other members of the genus Homo.
X-ray studies
Scientists from the United Kingdom, France and Italy have studied teeth from Neanderthals with X-rays from the European Synchrotron Radiation Facility (ESRF).
They found that the dental development of Neanderthals is very similar to modern humans, according to an ESRF press release. Their results are published in a recent issue of Nature.
Scientists used the ESRF X-rays to study the enamel dentine junction of a deciduous and a permanent Neanderthal molar tooth (approximately 130,000 years old) that was found on a site in France.
Teeth express genetic differences found between individuals and different populations more efficiently than any other tissues preserved in the fossil record.
Studies with teeth can identify a timescale on the entire period of dental development that occurs from before birth until adulthood.
The researchers noticed that the samples showed more complex folding of the enamel dentine junction than their modern human counterparts.
Some of the unique surface morphologies of Neanderthal molars clearly showed a deep embryological origin and are likely to have been functionally significant.
Crown, root growth
Thin ground sections of the same Neanderthal molars revealed that the crowns and roots did not grow faster than those of modern humans.
The permanent molar tooth studied had completed its root growth at about 8.7 years of age, which is typical of many modern human children today.
Changing physiology
Almost all deciduous teeth contained an accentuated birth line, or neonatal line that results from the changing physiology and stress of birth.
The Neanderthal deciduous also showed a neonatal line with evidence of the usual perinatal physiological stress but with no signs of additional postnatal stress.
Scientists predicted that the first permanent molar eruption in this Neanderthal (6.8 years) fits a dental development schedule similar to those found in modern humans. — Our Bureau
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