Tiny Knee Bone May Have Facilitated Human Upright Walking

Researchers suggest the lateral fabella evolved uniquely in humans, potentially aiding the transition from quadrupedalism to bipedalism.

The lateral fabella is a small bone found in the knee, present in around 39% of humans but not in all primates.
Scientists from King's College London analyzed 93 primate species to study the presence of the lateral fabella and other sesamoid bones.
The bone has been linked to osteoarthritis, being twice as common in individuals with the condition.
Findings indicate that the bone could have played a role in the evolution of bipedalism in early humans like Australopithecus.
The study points to an evolutionary process called exaptation, where existing structures take on new functions over time.