Primate evolution driven by ambush hunting: study

A Chinese research group has put forward a new hypothesis for the evolution of today's primates -- the ancestral species took on their typical look as they adopted a more carnivorous diet by ambushing prey in trees.

Primates including monkeys and human beings are characterized by grasping hands and feet, reduced claws and closer eye sockets which give them enhanced forward-looking ability.

A well-known theory proposed that the convergent orbits of the tree-inhabiting, insect-eating common ancestor of primates could help them locate prey. But it's hard to explain why other predators like wolves and eagles didn't evolve such a facial feature.

The zoologists from the Northeast Normal University analyzed a slew of non-primate species with high orbital convergence such as cats, night owls and flatfish.

They found that these animals are all ambush predators, hinting that the appearance of our ancestors was adapted as they learned to launch sneak attacks, according to the study published on Thursday in the peer-reviewed journal Science Advances.

Further, they recorded the sounds of squirrels climbing trees before and after their claws were trimmed. It turned out that clawless squirrels were significantly quieter climbers, an experiment that may explain why still-hunting primate ancestors evolved reduced claws to relax the prey's vigilance.

"The work is an important attempt to answer the controversial question of how diet may have influenced the evolution of primates," Wu Yonghua, professor at the Northeast Normal University and one of the paper's corresponding authors, told Xinhua.