London, Nov 21 : A new research has suggested that aerial bombardments by Stone Age humans might have pushed Neanderthals to extinction.
According to a report in New Scientist, changes in bone shape left by a life of overhand throwing hint that Stone Age humans regularly threw heavy objects, such as stones or spears, while Neanderthals did not.
"The anatomically modern humans would have this more effective and efficient form of hunting," said Jill Rhodes, a biological anthropologist at Bryn Mawr College in Pennsylvania, who led the new study.
"A warmer Europe would have opened up forests, enabling longer range hunting," she added.
Rhodes and a colleague studied changes to the arm bone that connects the shoulder to the elbow - the humerus - to determine when humans may have begun using projectile weapons.
"If we're trying to understand whether anatomically modern humans had projectiles, then why not read the signature that it can imprint in the skeleton," Rhodes said.
Studies of elite handball and baseball players suggest that frequent overhand throwing from an early age permanently rotates the shoulder-end of the humerus toward an athlete's back, compared to people who haven't spent much time hurling.
This bone rotation only occurs in the throwing arm, so a difference between the right and left arm in fossils could be a sign of projectile use, according to Rhodes.
To find out, she and Churchill measured humerus bones from Neanderthals and ancient and modern humans.
They found some evidence for projectile use in male European humans from around 26,000 to 28,000 years ago - the middle Palaeolithic period - who would have been contemporaries of Neanderthals.
Their right humerus bones were generally more rotated toward their back than their left, while Rhodes's team noticed no such asymmetry in Neanderthal arms.
"These upper Palaeolithic men were doing something different with their arms than the Neanderthals were," she said.