The day our human ancestors figured out fire must have been a pretty exciting one.

But none of the evolutionary connections among human ancestors are clear.

"We might even have a common human ancestor somewhere way back."

This early human ancestor has been found nowhere else in Africa.

Also uncovered nearby are the remains of early human ancestors more than five million years old.

But before about two billion years ago, human ancestors branched off.

They no longer bear any physical resemblance to their human ancestors.

Our old- human ancestors didn't think they way we do.

Lucy may not even be a direct human ancestor after all.

Our earliest human ancestors appeared in Africa 2.5 million years ago.