Scientists have discovered the oldest fossilized remains of a human ancestor. It’s about a million years older than Lucy, it’s female, and is named “Ardi” (unfortunately not after a Beatles song).

All previously known hominids—members of our ancestral lineage—walked upright on two legs, like us. But Ardi’s feet, pelvis, legs, and hands suggest she was a biped on the ground but a quadruped when moving about in the trees.

They also theorize that bipedalism allowed the male to carry and bring food back to the female, which was a move away from brute strength towards monogamy.