Post by Shadow on Feb 3, 2006 8:42:41 GMT -5
New Scientist
# 11:05 01 February 2006
# NewScientist.com news service
# Gaia Vince
Dads-to-be pile on the pounds during their partners’ pregnancy too – at least in some monkey species, new research suggests. The findings may illuminate the biological changes that occur in men to encourage effective fatherhood, since the primates studied are exceptionally good parents.
Pregnancy is something that not all expectant fathers miss out on – male "sympathetic pregnancies" have been reported in humans but never systematically studied. They are often regarded as psychosomatic events.
Do human males act differently when their partner's belly swells?
Discuss this story >>
Now a US team has studied the parental weight patterns of common marmosets and cotton top tamarins – two squirrel-sized, monogamous primate species – from conception to birth. Each month the 25 prospective dads and 33 pregnant mums were weighed. The creatures’ food supply was maintained but not increased during the gestation periods for the marmosets (five months) and tamarins (six months).
"We found that the males gained on average an extra 10% of their body weight during the pregnancy," says Toni Zeigler who led the research at the University of Wisconsin-Madison National Primate Research Center. The weight gain was not as pronounced as for the females, but was acquired earlier in the pregnancy – about midway. The majority of female weight gain occurred during the final weeks of gestation.
Monkey on his back
"Weight gain is beneficial for the males because it prepares them for the higher energetic costs involved after the babies are born," Zeigler explains. "The monkeys usually have twins and they are born fairly large – about 20% of their adult weight – and the father mostly has to carry them on his back."
The males' weight gain is probably a result of their producing greater levels of prolactin – the same hormone that encourages milk production in the females. "Our earlier studies showed that prolactin levels increase in males halfway through pregnancy, when the females experience a hike in corticosterone – a hormone involved in sending and receiving pheromones," she adds.
# 11:05 01 February 2006
# NewScientist.com news service
# Gaia Vince
Dads-to-be pile on the pounds during their partners’ pregnancy too – at least in some monkey species, new research suggests. The findings may illuminate the biological changes that occur in men to encourage effective fatherhood, since the primates studied are exceptionally good parents.
Pregnancy is something that not all expectant fathers miss out on – male "sympathetic pregnancies" have been reported in humans but never systematically studied. They are often regarded as psychosomatic events.
Do human males act differently when their partner's belly swells?
Discuss this story >>
Now a US team has studied the parental weight patterns of common marmosets and cotton top tamarins – two squirrel-sized, monogamous primate species – from conception to birth. Each month the 25 prospective dads and 33 pregnant mums were weighed. The creatures’ food supply was maintained but not increased during the gestation periods for the marmosets (five months) and tamarins (six months).
"We found that the males gained on average an extra 10% of their body weight during the pregnancy," says Toni Zeigler who led the research at the University of Wisconsin-Madison National Primate Research Center. The weight gain was not as pronounced as for the females, but was acquired earlier in the pregnancy – about midway. The majority of female weight gain occurred during the final weeks of gestation.
Monkey on his back
"Weight gain is beneficial for the males because it prepares them for the higher energetic costs involved after the babies are born," Zeigler explains. "The monkeys usually have twins and they are born fairly large – about 20% of their adult weight – and the father mostly has to carry them on his back."
The males' weight gain is probably a result of their producing greater levels of prolactin – the same hormone that encourages milk production in the females. "Our earlier studies showed that prolactin levels increase in males halfway through pregnancy, when the females experience a hike in corticosterone – a hormone involved in sending and receiving pheromones," she adds.