Å®ÉúСÊÓƵ

A study of baboons in Kenya shows that the old adage ‘you are what you
eat’ is truer than might have been imagined. Stuart Altman, a primatologist
at the University of Chicago, has found that the quality of the nutrition
a young baboon receives determines its later reproductive success very closely.
Such success is a measure of Darwinian fitness.

‘By 70 weeks, before the completion of weaning, a female baboon’s lifetime
fitness is largely established,’ says Altman. ‘Yet, at that age they are
still nursed, still sleep in their mothers’ arms, are still three years
away from puberty, and about four years from when they will conceive their
first offspring.’ According to Altman, this is ‘a very surprising result’
(Proceedings of the National Academy of Sciences, vol 88, p 420).

Altman measured the food intake of a troop of baboons aged between 30
and 70 weeks, in Amboseli National Park on the border between Kenya and
Tanzania. He found that of all the nutrient criteria, the two that were
the best able to predict reproductive success were protein intake and energy
intake.

Altman focused on females in the troop, because it is easier to monitor
their reproductive success reliably than that of males. Reproductive success
is measured in terms of the length of the reproductive span, the number
of offspring produced, and the survival of those offspring to one year of
age.

Altman found that even though all the animals fell below ‘optimum diet’,
given the food resources available, those that came closest did best in
the end. This is not a case of individuals that are badly nourished failing
to reproduce effectively, he says. Instead, reproductive success is graded
and directly related to the quality of nutrition within a normal range.

‘Do some animals have higher fitness because they eat better, or do
they eat better because they are more fit?’ asks Altman. ‘I suspect that
both are true,’ he says.

There are, however, no good data to indicate whether reproductively
fit mothers produce reproductively fit offspring. Even if scientists could
demonstrate such a correlation, it would still be difficult to be certain
whether the effect were the result of social or genetic transmission. Experiments
of the most Draconian nature would be necessary to untangle these possibilities,
says Altman, ‘and you wouldn’t be able to do them in a natural setting like
´¡³¾²ú´Ç²õ±ð±ô¾±â€™.