Mark Ridley works in the Department of Zoology, Oxford University. He previously held posts at Emory University in Atlanta and at Cambridge University in England. His books include the standard college text Evolution and Mendel’s Demon. He has also edited anthologies on Evolution and A Darwin Selection. Simon Critchley is a best-selling author and the Hans Jonas Professor of Philosophy at the New School for Social Research. His many books include The Book of Dead Philosophers, Bowie, and Tragedy, the Greeks, and Us.