When we look for the origins of all humanity today, let's not just look at Europe, because I think Africa was the cradle, the crucible that created us as Homo sapiens.

We are placed in the genus of Homo, which is Latin for man - Homo sapiens: supposedly wise men. I sometimes think - wonder - whether we really are wise men.

The right question to ask from a Darwinian prospective is what was it about bipedalism that was so advantageous? Why did it lead to a - why did that adaptation ultimately lead to a species Homo sapiens that has come to dominate the planet today with six and a half billion people?

I think that many of my ideas are correct, but I'll bet you, before my death other discoveries will be made that will prompt me to alter various ideas I have about human evolution.

When I realized, in 1978, that Lucy did represent a new species of human ancestor, and that I had an opportunity to name this new species, I realized this was a revolutionary step in understanding human origins.

I find a tremendous receptivity among the public for the subject matter of, 'Where did we come from and how did we get here?' People are thirsty and hungry for information on our origins. I feel a responsibility as a major figure in the area... to convey to the public the knowledge of human origins in a way that is understandable to them.