Our Ancestors Were Knuckle-Walkers

Updated August 5, 2020 | Infoplease Staff

And other recent science discoveries

by Otto Johnson

More Discoveries

A new study by Brian Richmond and David Strait of George Washington University that scrutinized the fossilized wrist joints of two of our earliest known human ancestors, A. afarensis (best known as “Lucy”) and A. anamensis, concluded that our earliest known human ancestors probably walked on their knuckles in a way similar to modern chimpanzees and gorillas.

Did Humans Evolve From Tree-Dwellers or Animals on Ground?

This discovery lends support to the theory that humans didn't evolve from tree dwellers, but from ancestors who were already adapted to walking on the ground.

It's All In the Wrist

The researchers compared the fossilized wrist joints from known human ancestors with the wrist joints of other primates. The wrist anatomy of Lucy and her cousins resembles that of chimpanzees and gorillas in having features that buttress the wrist joint and help to lock the wrist into a stable position so that the animal can support its weight on its fingers. It was not until the later species, A. africanus, at 2 to 3 million years ago, that evidence of a more humanlike, flexible wrist joint exists.

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