Washington -
Neanderthal children grew up faster than humans, according a study on Monday that suggested that modern kids' lengthy childhoods may be a relatively new phenomenon that has boosted our longevity.
The study is the latest to highlight small but crucial differences in early development between modern humans and our closest cousins who became extinct about 28 000 years ago.
Researchers made the discovery after using a new “supermicroscrope” with an advanced X-ray technique to examine the teeth of previously discovered fossils of Neanderthal children.
“Young Neanderthals' teeth growth - a proxy for overall development - was significantly faster than in our own species, including some of the earliest groups of modern humans to leave Africa some 90 000 to 100 000 years ago,” said the study in the Proceedings of the National Academy of Sciences.
“This indicates that the elongation of childhood has been a relatively recent development.”
Scientists at Harvard University, the Max Planck Institute for Evolutionary Biology and the European Synchrotron Radiation Facility examined the remains of some famous Neanderthal children found in France and Belgium during their five-year study.
Using a highly developed “supermicroscope” that helped peer deeper into the dental fossils without damaging them, researchers found that the first hominin fossil ever discovered, that of a young Neanderthal girl found in Belgium, was actually about three years old when she died, not four to five as previously thought.
“Teeth are remarkable time recorders, capturing each day of growth much like rings in trees reveal yearly progress,” said lead study author Tanya Smith, assistant professor of human evolutionary biology at Harvard.
“Even more impressive is the fact that our first molars contain a tiny 'birth certificate’, and finding this birth line allows scientists to calculate exactly how old a juvenile was when it died,” she said.
“These new methods present a unique opportunity to assess the origins of a fundamentally human condition: the costly yet advantageous shift from a primitive 'live fast and die young' strategy to the 'live slow and grow old' strategy that has helped to make us one of the most successful organisms on the planet.”
Previous research has pointed to differences in maturation and lifespan between early humans and apes, whose females have shorter pregnancies that result in offspring that grows up faster and begins to reproduce at younger ages than humans.
For examples, chimpanzees on average bear their first babies at age 13, compared to age 19 in humans.
However, it is less clear when this evolutionary shift began to occur in the path of human development, and scientists have debated whether various development patterns differed between Neanderthals and homo sapiens, from which modern humans evolved.
The advances in examining the age of the teeth were possible by using what the study called a “supermicroscope” that employs “extremely powerful X-ray beams” developed at the European Synchrotron Radiation Facility in Grenoble, France.
The synchotron at Grenoble is the largest in the world, and has been “quietly” visited by museum curators and scientists bearing rare fossils from around the world so that they can be imaged and analysed anew, the study said.
A study released last week showed that the brains of Neanderthals, believed to be modern humans' closest ancestor, and humans were similar at birth but developed differently in the first year of life. - Sapa-AFP