We have language and they do not. Chimps communicate by embracing, patting, looking - all these things. And they have lots of sounds. But they cannot sit and discuss. They cannot teach about things that are not present, as far as we know.
I don't spend that much time being introspective, believe it or not. All I know is that I grew up not questioning God because that's how you are. God was there like the birds and the wind.
What you do makes a difference, and you have to decide what kind of difference you want to make.
I had been told from school onwards that the best definition of a human being was man the tool-maker - yet I had just watched a chimp tool-maker in action. I remember that day as vividly as if it was yesterday.
I think the most important thing is to keep active and to hope that your mind stays active.
It was because the chimps are so eye-catching, so like us and teach us so much that my work was recognised worldwide.