GIRLS who have a good relationship with their father hit puberty later than
those who don鈥檛 get on so well with dad, say researchers in the US and New
Zealand.
Although genes and factors such as diet and exercise are known to affect the
timing of puberty, little is known about social influences. So Bruce Ellis of
the University of Canterbury in New Zealand and his colleagues at Vanderbilt
University in Nashville, Tennessee, studied 173 girls and their families in
three towns in Tennessee and Indiana. The families were first interviewed eight
years ago, before the girls entered kindergarten at the age of 5, and the girls
have answered detailed questionnaires each year since then.
At the start of the study, the researchers conducted two interviews of least
two hours each in the girls鈥� own homes. The interviewers also watched the
families during a meal, for instance, to assess how the parents鈥� interacted with
each other and with their daughters and find out if there was a lot of
encouragement and affectionate contact or discipline and harsh words.
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As the girls grew older, their annual questionnaires asked about the onset of
puberty鈥攊f they had any pubic hair, if their breasts were starting to show
or if they had had their first period. Most girls had had a period by age 13,
says Ellis, but there was a great deal of variation.
The researchers found a striking association between how well the girls got
on with their fathers when they were little and how old they were when they
entered puberty. The interaction between the girls and their fathers seemed to
have a far more significant effect than the girls鈥� relationship with their
mothers.
Girls from families where there was no father, or where the father was
abusive and disruptive, tended to develop early compared to girls whose fathers
had been actively involved in raising them (Journal of Personality and
Social Psychology, vol 77, p 387). 鈥淎 father鈥檚 investment is important,鈥�
says Ellis. 鈥淚t鈥檚 not only behavioural, it鈥檚 physiological.鈥�
Ellis suspects that paternal investment early in life gives girls
physiological cues about what kind of reproductive strategy to pursue. 鈥淟ong
ago, it might have benefited girls to be early reproducers in response to low
investment from their fathers,鈥� he says. But he cannot yet rule out the
possibility that the girls who reached puberty early were simply following their
mother鈥檚 pattern. Ellis is collecting data from the mothers to see if this is
the case.