Time of Our Lives by Tom Kirkwood, Weidenfeld & Nicolson, 拢20, ISBN
0297842471
TOM KIRKWOOD was soaking in the bath one winter night in 1977 when it
suddenly dawned on him why we age. It was one of those ideas that seems so
simple and obvious you wonder why no one thought of it before. 鈥淭he reason that
you and I will grow old and die, I am sorry to say, is that we are disposable,鈥�
writes Kirkwood in Time of Our Lives.
In the late 1970s, most gerontologists believed that our bodies are
programmed to age, having evolved an in-built 鈥渟uicide鈥� mechanism for preventing
overpopulation. Animals in the wild rarely age, however鈥攖hey live fast and
die young. The programmed death theory also overlooked the fact that natural
selection acts on individuals, not populations. Even if there were a genetic
ageing program, an animal with a damaged program would tend to live longer and
have more offspring than its rivals, whether or not the population was
overcrowded.
Advertisement
As Kirkwood lay in his bath, he realised that quality control is the key.
Given that there is a risk of 鈥渁ccidental鈥� death in the wild, through disease,
predation, starvation and so on, it is in our genes鈥� best interests to economise
on the repair and maintenance of DNA and proteins in the vast majority of our
cells, the non-reproductive 鈥渟oma鈥�, investing just enough to see us through to
sexual maturity in reasonable shape. Then, alas, we are heaved onto the scrap
heap. Nothing is too good for germ cells, though, which are charged with
perpetuating our precious genes. Gametes get Deluxe Quality Control.
Kirkwood鈥檚 hunch was that cellular repair and maintenance are expensive in
energy terms, and biochemists have since proved him right. It is as if our genes
are unscrupulous factory owners, skimping on quality control and exploiting
their workforce to earn the profits needed to spread their empires. But the
鈥渄isposable soma theory鈥� of ageing is not all gloom. 鈥淥nce we realise what are
genes are up to,鈥� Kirkwood says, 鈥渨e can start to discover what actually causes
补驳别颈苍驳.鈥�
Since his bathtime breakthrough, Kirkwood has become Britain鈥檚 first
professor of biological gerontology at the University of Manchester and a world
authority on ageing. His disposable soma theory has entered the mainstream,
though it has been known to surface on the other side of the Atlantic under
different guises. In Time of Our Lives, Kirkwood describes the latest
insights into the cellular basis of senescence, along the way revealing why
women tend to live longer than men and the deep connection between cancer and
ageing.
He debunks the 鈥渆xtract of monkey gland鈥� school of eternal youth and also
gives short shrift to the idea that the secret to reversing senescence lies with
a few 鈥渁geing genes鈥�. Instead, he argues that each new discovery of genes linked
to the ageing process is only a small piece of a bigger picture: ageing does not
have a single cause, but is the result of an accumulation of molecular errors at
all levels, simultaneously affecting different parts of the body in many
different ways.
Kirkwood has written a popular classic that can be read and understood by
anyone who has looked in the mirror and groaned. His writing is rich in stories,
anecdotes and thought experiments. For example, as an illustration of the
dilemmas facing a rapidly greying society, he asks us to imagine we are a
helicopter pilot who must choose whom to rescue first from a slowly sinking
boat. Should it be the 42-year-old father of three, or the hard-working
64-year-old who is just beginning to enjoy a well-earned retirement, or the
18-year-old student with no dependents and no fixed plans? Healthcare providers
working with limited budgets already face agonising decisions such as this, and
the pressures can only get worse. By 2008, there will be more pensioners than
children living in Britain, according to the latest projections from the Office
for National Statistics.
All this and we haven鈥檛 even begun to challenge the underlying biological
causes of senescence. But ageing itself, asserts Kirkwood, 鈥渋s neither
inevitable nor necessary鈥�. And as he points out in the epilogue, a short
whimsical story set hundreds of years hence, conquering ageing will create a
whole new set of problems. 鈥淭he only known strategy to cope with this awesome
prospect, short of mind-numbing drugs and escapist diversions, was to cultivate
and preserve an exaggerated love of oneself.鈥�