We meet probably the most famous of all our early ancestors. She is Lucy, from the species Australopithecus afarensis and she lived 3.2 million years ago. Lucy's species traded life in the trees for life on the ground, but walking upright came at a price and it is one we are still paying today.We meet probably the most famous of all our early ancestors. She is Lucy, from the species Australopithecus afarensis and she lived 3.2 million years ago. Lucy's species traded life in the trees for life on the ground, but walking upright came at a price and it is one we are still paying today.