Think of the labrum as a ring of soft tissue that holds the ball of the femur, or thighbone, snugly in the hip joint's socket.

CNN: Gaga's injury related to 'being active'

And recent computed tomography (CT) scans of the thighbone of a six-million-year-old Kenyan creature known as Orrorin tugenensis suggest it might have had quite a human gait.

BBC: NEWS | Science/Nature | Scientists unearth early skeleton