Why do we live as long as we do? Why do mice live 2 years, and elephants 30? In the first of a new two part series, Andrew Luck-Baker investigates how and why we live as long as we do, and why different species have different lifespans.

Is there an advantage to living just one day like the mayfly, or has the bowhead whale got it right by living a whopping 200 years? He pays a visit to the one of the oldest organisms on the planet and talks to the scientists who are studying the biological switches that control when we die.

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In the second part of this series on why we live as long as we do, Andrew Luck-Baker investigates the science of ageing.

He talks to scientists who have uncovered the genetic switches that control when and how we age, and in doing so may have discovered the key to switching these genes off.

Already they've had remarkable success in prolonging the life of tiny worms.

Could the ultimate elixir of life be only a short way off in humans?