By Clare Wilson.
A skull was found in Ethiopia.
PvE and Alamy.
The extra-large canine teeth that are seen in most other male primate at least 4.5 million years ago may have been lost by male hominins. The researcher behind the finding says it's possible that females preferred less aggressive mates as male human ancestors became less aggressive with each other.
Modern-day human males have smaller canines than great apes. Males have larger canines than females for most other primate. Larger canines are more likely to fight for access to females.
It's not clear when the male canines shrank because the fossils that are millions of years old don't have a sex assigned to them. The change in tooth size is thought to have happened when the ancestors of humans and Chimpanzees split about 7 million years ago.
