Longer life for childless women

PEOPLE WHO are genetically destined to live a long life are also more likely to have fewer children, according to a study of 33,000 European aristocrats.

Scientists who analysed the longevity and family size of aristocrats born between 1740 and 1875 have discovered evidence to suggest that those who lived longer did so because their bodies were less suited to rearing offspring.

The findings fit in with a theory of Darwinian survival, which says that some animals are genetically programmed to die young and have many offspring whereas others are less fertile and so live longer.

Rudi Westendorp, of Leiden University in the Netherlands, and Tom Kirkwood, of the University of Manchester, obtained the records of 19,830 male and 13,667 female aristocrats to compare life spans against the ages when they had children, in addition to family size.

Professor Kirkwood, a biological gerontologist, was testing his "disposable soma theory", which predicts that any investment the body - or soma - makes in ensuring fertility and reproduction is diverted away from repairing the continual damage caused by the ageing process. This "trade off" has already been established by experiments on fruit-flies, which show that individual animals who are genetically programmed to have a long life are less fertile than those destined to die young.

The scientists found a clear correlation between extended longevity and small family size. Almost half the women who surpassed 81 had no children, yet fewer than one-third who died before this age were childless, they report in the journal Nature.

"We are not saying those people who choose to have fewer children are more likely to live longer," Professor Kirkwood said. "It is not conscious, but a biological trade-off between having offspring and living longer."