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News Release 06-072

Hyena Mothers Give Their Cubs a Helpful Dose of Hormones

High androgen levels late in pregnancy give dominant mother’s cubs a head-start at being pack leaders

A sleepy female spotted hyena lounges with her seven-week old cubs in Kenya.

A sleepy female spotted hyena lounges with her seven-week old cubs in Kenya.


April 26, 2006

This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts.

Scientists have discovered that a dominant hyena puts her cubs on the road to success before they are born by passing on high levels of certain hormones that make her budding young leaders more aggressive and sexually advanced.

The report, published in the April 27 issue of Nature, is the first study in mammals to demonstrate a relationship between a female's social rank and her ability to influence her offspring's behavior through prenatal hormone transfer. Previously, this phenomenon had only been documented in birds.

Michigan State University's Kay Holekamp, together with her colleagues, spent almost 10 years sampling androgen levels from free-ranging hyenas in Kenya. Androgens are hormones, such as testosterone, that control development of typically masculine characteristics like aggression, muscle development and sexual behavior.

The team found that alpha females had higher androgen levels late in pregnancy when compared to the subordinate, pregnant females in the pack. Consequently, the cubs of the alpha females were more aggressive and exhibited more sexual play, characteristics that elevate the chances for life-success in both sexes.

In hyena packs, male-female social roles are reversed from what is normally found in nature--that is, female hyenas are larger, more aggressive and dominate the group. They even have deceptively male-like genitalia, leading to the misconception that they are hermaphrodites.

According to Jerry Wolff, the National Science Foundation manager whose program helped support this work, "this is a clear example of how the complex integration of genetics, physiology and social environment leads to reproductive success for this species."

Wolff believes that Holekamp's work will create a paradigm shift in how scientists view the establishment of dominance in mammals.

For more information about this work see the Michigan State University press release.

-NSF-

Media Contacts
Richard (Randy) Vines, NSF, (703) 292-7963, email: rvines@nsf.gov
Sue Nichols, Michigan State University, (517) 353-8942, email: nichols@msu.edu

Program Contacts
Jerry Wolff, NSF, (703) 292-8423, email: jwolff@nsf.gov

Principal Investigators
Kay Holekamp, Michigan State University, email: holekamp@msu.edu

The U.S. National Science Foundation propels the nation forward by advancing fundamental research in all fields of science and engineering. NSF supports research and people by providing facilities, instruments and funding to support their ingenuity and sustain the U.S. as a global leader in research and innovation. With a fiscal year 2023 budget of $9.5 billion, NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and institutions. Each year, NSF receives more than 40,000 competitive proposals and makes about 11,000 new awards. Those awards include support for cooperative research with industry, Arctic and Antarctic research and operations, and U.S. participation in international scientific efforts.

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