Killer whales live in multi-generational family groups. Each family is led by an old matriarch, often well into her 80s. The rest of the group are her daughters and sons, and grand-children. Especially intriguing to Darren is that female orca go through something like the menopause - an extremely rare phenomenon in the animal kingdom, only documented in just five species of toothed whales and of course in humans. Halting female reproduction in midlife is an evolutionary mystery, but it is one which Darren Croft argues can be explained by studying killer whales.

Darren is Professor of Animal Behaviour at the University of Exeter. He talks to Jim Al-Kalili about his research on killer whales, his previous work revealing sophisticated social behaviour in fish, his life on the farm, and the downsides and upsides of being dyslexic.

Presented by Jim Al-Khalili

Produced by Andrew Luck-Baker