In a study appearing in the April 26 edition of the international science journal Nature, Michigan State University zoology professor Kay Holekamp and Stephanie Dloniak along with Jeffrey French from the University of Nebraska, report that high-ranking, dominant spotted hyena mothers pass to their offspring high levels of certain hormones that make cubs more aggressive and sexually vigorous in other words more likely to survive, thrive and reproduce.

The study shows that alpha females have higher levels of androgen during the final stages of pregnancy than lower-ranking group members.

What this means is that there are gifts a mom can give to her baby, said Holekamp, who also is a recent recipient of a 2006 Guggenheim Fellowship for her work on hyenas. She can manipulate her offsprings behavior and help her kids to survive and reproduce successfully by transferring status-related traits via prenatal hormone exposure.

This research sheds light on mammalian reproductive biology and helps us imagine how evolution might have produced such a bizarre product, Holekamp said

The findings result from nearly two decades of National Science Foundation-funded research spent studying wild spotted hyena populations in Kenya. The paper outlines the first instance where researchers have shown that a female mammals hormones can influence her offsprings behavior and appearance.

Androgen is just one of the many hormones traveling across the placenta to the developing fetus. This hormone mediates masculine characteristics like aggression, muscle development and male-typical sexual behavior.

But its not just the male cubs that stand to benefit from the maculinizing effects of androgens. Females gain just as much.

Normally, when it comes to muscl
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Contact: Kay Holekamp
Holekamp@msu.edu
517-432-3691
Michigan State University
26-Apr-2006