Washington, September 9 : A new study of Neanderthal skeletons has suggested that the species grew quickly but reached sexual maturity later than so-called modern humans-and quite possibly survived to a ripe old age.
According to a report in National Geographic News, the study also suggests that Neanderthals had a harder time of child bearing and possibly child raising, due to which, modern humans may have simply outbred their heavy-browed rivals.
By studying the skulls of Neanderthal babies, researchers were able to estimate how quickly the infants' brains grew.
They found that between birth and adulthood, a Neanderthal brain expanded faster than that of a modern human. The biggest growth spurt occurred in the first couple of years of life.
Neanderthal heads-and therefore brains-were already known to be larger than those of modern humans.
But that doesn't mean Neanderthals matured any faster.
"It shows that brain growth in modern humans and Neanderthals was quite similar and suggests that a fast pace of development was unlikely in the early years," said Chris Dean of University College London.
The University of Zurich's Maria Ponce de Leon and colleagues pieced together three Neanderthal skeletons: one newborn from Mezmaiskaya Cave in Russia and two infants aged 19 and 24 months, respectively, from Dederiyeh Cave in Syria. In addition, the scientists reconstructed the pelvis of an adult female Neanderthal skeleton, found in Tabun Cave in Israel.
By analyzing the skeletons, the team found that Neanderthal babies were born with similar-size skulls to those of modern human babies. However, the shape of the face was different.
"Even in a newborn (Neanderthal) baby, we could see the conspicuous protrusion of the forehead that distinguishes Neanderthals," said study co-author Christoph Zollikofer, also of the University of Zurich.
By creating virtual reconstructions of the Neanderthal skeletons, the scientists also investigated the birthing process.
"The birth would have been at the limit of what was possible, and the baby's head would have had to turn by a quarter in order to get through the narrow lower pelvis," Zollikofer said.
Young Neanderthals' rapid growth required lots of energy.
"Neanderthals must have had a rich diet in protein and fat for children to fuel rapid growth in (their) brains," said Holly Smith of the Museum of Anthropology at the University of Michigan.
Mothers also likely had to consume vast quantities of calories to produce enough breast milk.
According to Zollikofer, this energy-intensive child rearing may have caused somewhat longer interbirth intervals, or somewhat older mothers.
This may explain why modern humans eventually outcompeted Neanderthals.
"If one population reproduces just one percent more than another, then it can eventually replace the other population," Zollikofer said.