3. Chilling Out

In the third of her Christmas Lectures, Nancy Rothwell reveals how humans and animals alike have evolved to keep their body temperatures constant, even when the temperature of their habitats is changing. After journeying down to the chilly depths of the ocean to tell us how sharks keep warm, Nancy returns to the warm climes of the Arabian desert to explain why some Bedouins still wear dark robes despite knowing that black absorbs more heat than white.