Walking Upright: A Key to Evolution

Our ancestors learned to walk upright way before their brains got big. For years,

everyone thought a big brain had to come first. But fossils like the famous "Lucy"

proved that wrong. She and her relatives had small, ape-sized brains, but their skeletons—from

their pelvis to their angled knees—were totally adapted for walking on two legs.

And they weren't alone! Other species, like the "Nutcracker Man," had massive

jaws and huge chewing muscles for a tough plant diet. It was a wild time of evolutionary

experiments. Ultimately, walking freed our hands, which led to making

tools and, much later, the big brains we have today.