Scientists examining fossils have discovered that Neanderthals were exposed to more testosterone during development which is likely to make them more unreconstructed in their behaviour.
That means they were more likely to start fights over mates and hierarchy in the group and more likely top have multiple partners.
The team from Liverpool, Oxford, Southampton and Calgary Universities, studied the fossilised finger bones of extinct apes, Neanderthals and hominins – extinct members of the human family – to learn more about their hormonal activity.
It is known that the longer the ring finger is compared to the index finger is a mark of how much testosterone exposure there was in the womb.
High levels of the hormones increase the length of the fourth finger in comparison to the second finger, resulting in a low index to ring finger ratio.
The team found that the fossil index fingers of Neanderthals were longer compared with the ring finger than most living humans, which suggests that they had been exposed to higher levels of testosterone.