Fossils of early humans and their ancestors show how our species evolved gradually from ape-like ancestors in Africa. Three important finds are Ardi, Lucy and fossils found by Richard Leakey's team.
Ardi lived about 4.4 million years ago. Her foot had a big toe that could grip, so she could still climb trees, but her pelvis suggests she could also walk upright on two legs. Lucy lived about 3.2 million years ago. Her bones show she walked upright on two legs, which is described as being bipedal, but she still had a small brain.
Richard Leakey's discovery of fossils from 1.6 million years ago showed a body shape much more like ours, with longer legs and a larger brain than Lucy. Together these fossils show a gradual change over time, from climbing and walking to fully upright humans with bigger brains. Fossils are rare and often incomplete, so ideas may change when new ones are found.