Fatherhood 'causes fall in level of testosterone'
(telegraph)
Updated: 2005-11-09 17:24

Fathers have lower levels of the male sex hormone than single men, according to evidence published today.

As well as revealing how levels of testosterone fall as a result of human "pair bonding", the study suggests that, when a marriage is not going well, men tend to have higher levels of the hormone, which has been linked to aggression, assertiveness and the drive to seek out women for sex.

Previous studies in America have shown that the levels of the hormone are lower when a man marries and has children, presumably to improve relationships with a long term mate and their offspring.

To see if this is a universal feature of male behaviour, and whether high levels can show if a marriage is in trouble, Dr Peter Gray from the University of Nevada, Las Vegas, and colleagues at Harvard studied men in Beijing.

For the study, published today in the Proceedings of the Royal Society, Biological Sciences, 126 men (66 unmarried, 30 married non-fathers, 30 married fathers) were drawn from a Chinese university community between the ages of 21 and 38.

The fathers had significantly lower testosterone levels in their saliva than unmarried men, the team reports, adding that this was the first time this effect had been seen outside America.

The team also found that in married men without children, a higher level of testosterone was linked with a lower level of satisfaction with the marriage.