Even before this week, you had probably heard of Lucy, our famous Australopithecus afarensis ancestor. She lived in what is now Ethiopia, a little more than 3 million years ago — a time when we were just learning to stand upright and walk on two legs on the ground. Lucy lets us study how we evolved into the modern humans we consider ourselves today. We knew that Lucy died relatively young, and now we know physically how it happened: New evidence shows she died after falling out of a tree.
Lucy might have spent much of her life on the ground, but researchers believe she and her kind still climbed trees fairly regularly for safety and sleep. In the journal Nature, researchers concluded that a fall from a particularly tall tree caused Lucy to sustain the injuries, including multiple bone fractures, that killed her.
Cognitively, we’ve evolved significantly, but physically we’re still kinda one big soft spot. Compared to most of the animal kingdom, actually, we’re fairly lame. We’re not particularly strong or fast or durable. Nor are we becoming much more durable with time. We break extraordinarily easily; the last 3 million years haven’t changed that.
After Australopithecus afarensis evolved to walk on two legs, they became pretty terrible at tree-climbing; that was simply the trade-off as we continued to evolve. This may have been why Lucy tumbled to her death (though it should be noted that even more agile primates still die from falling out of trees today), stretching her arms in front of her in an attempt to break her fall, exactly as we would do today.
In other words, we now know how Lucy died. And weirdly, she died in a way that proves we humans still haven’t changed much.