A matter of sex and death: “Ageing and our own mortality could be the price we pay for
human fertility”, says Professor of Medicine and theoretician of ageing Tom Kirkwood.

The distinction between germ-line and soma enabled such
amazing advances in the evolution of life that we might almost
forgive the terrible price we have paid. For it was this, not sex,
that caused us to age and die. … To understand why the soma/germ-line distinction is so
important for ageing, we should know that the germ-line
cannot be allowed to fail in its duty of keeping going
indefinitely. If it did — if, for example, it permitted damage to
build up in its DNA sequence — it would rapidly become
extinct. Some change to the DNA sequence must occur, or
evolution would be stalled, but the kind of damage that builds
up in the somatic cells of our bodies would be intolerable in the
germ-line… But with the soma, there is no
corresponding requirement for somatic cells to keep their DNA
in good shape indefinitely. It does not matter, biologically, if
our somatic cells eventually fall apart. The somatic cells
comprise the individual and that is all that they will be required
to do. Life in the natural world is brutish and short. All that the
organism needs from its somatic cells is that they can keep the
soma in good shape until an age when the likelihood of still
being alive is negligible. When we factor in that the care and
repair of somatic cells does not come cheap, it makes sense to
cut back maintenance of the somatic cells and to divert that
energy into helping with reproduction. The result was that the
soma became disposable, and with that came ageing. The Times of London