During the next ten years he tried to fit the theories about how children develop with what mothers told him about their children.

VOA: special.2009.03.15

But it was on the Galapagos Islands off the coast of Ecuador that Darwin found creatures that made him wonder about how species develop and change.

VOA: special.2009.02.25

Genes decide how and when each kind of cell will develop in differing organs.

VOA: special.2010.03.23

"People can look at things and be curious about them, but if you are an explorer you want to know why and how and maybe develop an experiment to test the hypothesis."

VOA: standard.2010.06.21