1x4 - The Giraffe

July 20, 2009

Veterinary scientist Mark Evans acts as guide as a team of experts investigate the giraffe. Creationists question how this extraordinary creature could have evolved such a long neck, but for evolutionary biologist Professor Richard Dawkins the anatomy of the world's tallest animal provides some of the best arguments in favour of Darwinian natural selection. For example, one nerve takes a huge detour up and down the long neck, from the voice box to the brain, via the chest - hardly the work of an `Intelligent Designer'. And, despite its length, the neck still only has seven vertebrae - the same number as almost all mammals, from mice to humans and whales. But it's no wonder the giraffe has the highest blood pressure of any animal; with a heart not much bigger than our own it must pump blood at high pressure around a towering body. It has evolved thick skin that acts as a natural 'G-suit' and a complex circulation system to avoid passing out when raising and lowering its head. And as the dissection team piece together the remarkable evolutionary story of the giraffe, biologist Simon Watt observes them in the field as they eat, forage and fight.