Jimmy Doherty continues to work his way through Charles Darwin's series of experiments that formed the basis of On the Origin of Species, like feeding human urine and sausage to Venus flytraps to see which the plant prefers. Some experiments are more tricky, though, requiring Doherty to catch a peacock or fiddle about with a flower's stamen and pistil. Interestingly, it seems that Darwin had a personal reason for investigating the problems caused by interbreeding. He was married to his first cousin Emma (not the only cousins within their families to marry) and was concerned that this was the reason three of his ten children died at an early age.