Inside Nature's Giants

The thoroughbred racehorse is one of the greatest athletes on the planet, galloping with incredible speed and stamina for such a large animal. It is the result of unnatural selection, and exists on a knife edge between glory and catastrophic failure. The team explore how this animal has been biologically engineered for speed. They dissect an elite racehorse to reveal the extraordinary spring system that propels it to 45mph, its super-sized organs and built-in turbo-booster. Simon Watt visits the top breeding centre in Europe to find out how to produce a champion; and Mark Evans investigates the science behind their phenomenal performance and their vulnerability to injury

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.

In this episode experts dissect a 65-foot, 60-ton fin whale - second only in size to its 'cousin' the blue whale - that has died after being stranded off the coast of Ireland. It's a race against time as whale anatomist Joy Reidenberg flies in from New York before the animal's decomposition causes it to explode on the beach. Veterinary scientist Mark Evans helps investigate why the animal died and explores its extraordinary anatomy. Using whale-size machinery, Joy and the team set to work amidst gale force winds, driving rain, blood, intestines, evil smells and freezing conditions. Meanwhile, advancing tides threaten to engulf the whale, as the team struggles to complete the operation. Beneath the blubber, the whale's unique anatomy holds vital clues to its evolution. Using a combination of dissection and computer graphics, the programme discovers an animal whose closest living relative is the hippo. Meanwhile, evolutionary biologist Richard Dawkins explains why the whale's ancestors may have taken to the water and the evolutionary problems that had to be overcome to transform a land-based mammal into an animal that swims among fish.