201104 milk tooth

Neanderthal milk teeth reveal their secrets

Neanderthal children grew and were weaned in much the same way as Homo sapiens, new research suggests.

Virtual rendering of a milk tooth. Credit: Stefano Benazzi

This contradicts a previous hypothesis that Neanderthals weaned their children later than modern humans do, and that such late weaning may have limited population growth and contributed to their decline.

An Italian-led team analysed milk teeth from three Neanderthal children who lived between 70,000 and 45,000 years ago. They were found in separate caves in the northeast of Italy, between the provinces of Vicenza and Verona.

Teeth grow and register information in form of growth lines – akin to tree rings – that can be read through histological techniques.

Combining this with chemical data obtained with a laser-mass spectrometer, the scientists were able to show, they say, that these Neanderthals introduced children to solid food at around five to six months of age. The findings are presented in a paper in the journal PNAS.

“The beginning of weaning relates to physiology rather than to cultural factors,” says Alessia Nava, from the University of Kent, UK.

“In modern humans, in fact, the first introduction of solid food occurs at around six months of age when the child needs a more energetic food supply, and it is shared by very different cultures and societies. Now, we know that also Neanderthals started to wean their children when modern humans do”.

Neanderthals are well studied, but their pace of growth and early life metabolic constraints are still highly debated.

“This work’s results imply similar energy demands during early infancy and a close pace of growth between Homo sapiens and Neanderthals,” says Stefano Benazzi, from Italy’s University of Bologna.

“Taken together, these factors possibly suggest that Neanderthal newborns were of similar weight to modern human neonates, pointing to a likely similar gestational history and early-life ontogeny, and potentially shorter inter-birth interval.”

Time-resolved strontium isotope analyses also led the researchers to report that Neanderthals were less mobile than has been suggested.

“The strontium isotope signature registered in their teeth indicates in fact that they have spent most of the time close to their home: this reflects a very modern mental template and a likely thoughtful use of local resources,” says Wolfgang Müller from Germany’s Goethe University.

Related reading: Clues in a Neanderthal’s milk tooth