Why do we still fear animals that pose no serious threat to us and how can the effect of that irrational fear be so overpowering? As Mike Williams discovers in this week’s Why Factor, the answers lie deep in our evolutionary past and deep inside our brains.

Mike faces his own animal fear at London Zoo, where we also meet people overcoming their fear of spiders. Arachnophobia is one of the most common animal phobias and American Psychologist Joshua New’s research suggests humans are better at identifying and locating spiders than any other perceived threat. Could our fear of spiders be a leftover from our evolutionary ancestors?

Neuroscientist Dr Dean Burnett reveals what happens in our brains when we’re frightened by animals, and this is not always by the traditional spider or snake. We hear from a woman in Greece who has a rather surprising animal phobia…

Presenter: Mike Williams Producer: Rose de Larrabeiti

Film clip: 1984 (1984) Umbrella-Rosenblum Films Production. Director: Michael Radford

Image: A tarantula spider. Credit : Credit: Miguel Rojo/Getty Images