Donald Johanson

As an undergraduate, I had an opportunity to go on a number of archeological digs. So I had experience excavating, digging up remains of ancient Indian villages in the Midwest and in the Southwest.

One has to take initiative in life to achieve what he or she wants.

Most achievers I know are people who have made a strong and deep dedication to pursuing a particular goal. That dedication took a tremendous amount of effort.

Commitment, belief and positive attitude are all important if you're going to be a success, whether you're in sports, in business or, as in my case, anthropology.

All mammals undergo a certain degree of diversification. Darwin knew that. When he drew a family tree, it had many branches on it.

I was aware of it, but I grew up in a very a-religious family. My mother never went to church, she never had any religious training or background. It was never a part of our social interaction.

It's very hard for all of us, when we've committed ourselves to a particular interpretation, to change our minds.

You don't just magically flip some evolutionary switch somewhere and transmute a quadruped into an upright-walking bipedal human.

Lucy brought with her an image of our human ancestors that you don't get when you find a jaw or an arm bone or a leg bone. Here was 40 percent of a single skeleton.

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.

What's changed is we now have good anatomical, geological, archaeological evidence that Neanderthals are not our ancestors. When I wrote 'Lucy,' I considered Neanderthals ancestors of modern humans. We have gone back twice the age of Lucy, six million years. And we see that upright bipedal walking goes back that far in time.

There have been some friendships lost over this. That's the most difficult for me. I find it very uncomfortable to know that I was at one time close friends with someone, and because of jealousies and misunderstandings and so on, these friendships have dissolved.