Charles is an Associate Professor in the School of Life Sciences, University of Lincoln, UK. Charles has worked on egg biology and incubation in a variety of roles for 40 years. Charles is interested in avian and reptilian incubation in a range of wild and commercially important species and has an interest in better understanding what the fossil record can tell us about reproduction of extinct species. Charles has edited four key texts on avian and reptilian incubation. The mathematics of egg shape put Charles off egg shape for years until geometric morphometrics allowed him to quantify shape in a relatively simple way, which piqued his interest in how egg shape was established.