Ubiquitous in Darwin's time, the idea of an unceasing improvement in life insinuated its way into evolutionary theory from the first. In interviews with today's major figures in evolutionary biology - including Stephen Jay Gould, Edward O. Wilson, Ernst Mayr, and John Maynard Smith - and in an intimate look at the discoveries and advances in the history and philosophy of science, Ruse finds this belief just as prevalent today - however it might be denied or obscured.

His book traces the delicate line between those who argue that science is and must be objective and those who deem science a "social construction" in the fashion of religion or the rest of culture. It offers an unparalleled account of evolutionary theory, from popular books to museums to the most complex theorizing, at a time when its status as science is under greater scrutiny than ever before.