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Alpha Females Made (by Androgens) AND Born

A recent study reported in New Scientist reveals that alpha females pump heavy amounts of male sex hormones to their in-womb puppies, something that the...

Joy  |  May 1st 2006


hyena pups

A recent study reported in New Scientist reveals that alpha females pump heavy amounts of male sex hormones to their in-womb puppies, something that the non-alpha females don’t do for theirs.

EVERY mother wants to give her offspring the best start in life – but it doesn’t usually involve pumping them full of hormones. Unless you’re a spotted hyena, that is.

These dog-like pack animals live in a strongly female-dominated society in which the most aggressive become “top dog”, and get first choice of food and males.

Zoologist Kay Holecamp of Michigan State University and colleagues carried out an analysis of the feces of animals living in the Masai Mara reserve in Kenya. They discovered that during the last few weeks of gestation the levels of male sex hormones or androgens in the top-ranking females rocketed. Pregnant females in subordinate ranks showed hardly any change in androgen levels.

This strong prenatal androgen shower produced significantly more aggressive cubs, ensuring that the females attained the same high status as their mothers. The male cubs would probably benefit too, the researchers say (Nature, vol 440, p 1190).

It is the first time that status-related traits have been shown to pass from mother to offspring in mammals, although it probably also occurs in primates, including humans, Holecamp says. “Nobody has thought to study it before.” She says there may be an optimum level of androgens, since super-aggressive females risk injury in fights.

Thanks to Jeannette W. for passing this article on to me.