Did Our Ancestors Sleep in Trees?

It happened fast—that’s all we know.

Perhaps the young girl fell out of a tree or was struck by an illness. Maybe she drowned. But 3.3 million years ago, a roughly 3-year-old Australopithecus afarensis died in modern-day Ethiopia.

From her misfortune has sprung a wealth of knowledge. She fossilized quickly, likely because she tumbled into a stream bed or rushing floodwaters. The movement of rocks and water were kind to her skeleton, leaving it largely intact and whole. And soon after her skull was spotted sticking out of a cliff wall in 2000, anthropologists realized they had something unprecedented on their hands.

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