Tiny knee bone linked to osteoarthritis ‘may have helped humans walk upright’

Researchers discovered that primates with these bones were 50 times more likely to have ancestors who also had them

The lateral fabella of different sizes on the back of a human knee (Imperial College London)

A tiny knee bone often found in people with a common type of arthritis may have helped humans evolve from walking on all fours to standing upright, scientists believe.

Not much is known about the mysterious lateral fabella – a bone about the size of a sesame seed that is found in around 39% of the population but absent in others.