Following the growth of biological knowledge in the past few decades, a few researchers now believe extension of the human lifespan might be within reach. Why do organisms – people included – age in the first place? Like machines, people wear out. However, a machine can usually be repaired. A good mechanic with a stock of spare parts can keep it going indefinitely, to the point where no part of the original remains. The question arises, of course, of whether the machine is worth repairing. It is here that people and nature disagree. From the individual’s point of view, survival is a must. You cannot reproduce unless you are alive. Since ageing is a sure way of dying, it is no surprise that people want to stop it from advancing. Moreover, even the appearance of ageing can be harmful. It reduces the range of potential partners who find you attractive – since it is a sign that you are not going to be around for a very long time to help bring up the baby – and this, in turn, restricts your ability to reproduce. There is a paradox, however: the individual’s evolved desire not to age is opposed by another evolutionary force, the disposable soma. The soma is all of a body’s cells apart from the sex cells. Its role is to get the sex cells, and thus the organism’s genes, into the next generation. But evolutionary logic seems to require the soma to age and die in order for a species to continue. There is thus a premium on reproducing early rather than conserving resources for a future that may never come.