Part of the show Cambridge Science Festival - Bioterrorism & Biological Weapons
Why do animals have to die ?
Dying actually serves a useful purpose because it is one way to eliminate weaker individuals, and the genes that they carry, from the population. If you inherit a bad gene which makes you less healthy and causes you to die at a young age, there is a lower chance of passing that faulty gene on to your future offspring, removing the gene from the population so that it cannot harm any of your descendents. But for most people the simple answer to why we die is because of the process of ageing. But if you ask why do we age, the simple answer is we don't know. It would appear that our bodies do not repair themselves adequately to the extent that we slowly accumulate damage to our cells and our DNA which eventually claims our lives. What we do know about ageing and longevity is that the process is heavily influenced by the genes that you inherit from your parents - in other words, if members of your family tend to live a long time, then you will too. One way to increase you life expectancy is to eat a diet which contains just enough calories to provide for your daily needs. Experiments on flies, monkeys and even people consistently show that low calorie diets like this can significantly increase your life expectancy, possibly by as much as 30%.