The place: sun-baked Olduvai Gorge, eastern Africa. The date: July 17, 1959. British archaeologist Mary Leakey noticed a piece of bone she thought might be part of an ancient human skull.
When Leakey and her team excavated the skull, they knew they had found something incredible. The skull was 1.7 million years old.
It was older than any skull found up to that point and showed that human-like beings had been around much longer than anyone had considered possible.
Older skulls have since been discovered, but Leakey’s find changed people’s understanding of human evolution.