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201514May13:01

Lemur females rule — thanks to testosterone!

Infor­ma­tion
pub­lished 14 May 2015 | mod­i­fied 14 May 2015
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Crowned lemur honeysuckleMales rule in most of the ani­mal world. But when it comes to con­ven­tional gen­der roles, lemurs — dis­tant pri­mate cousins of ours — buck the trend. Lemur girls behave more like the guys, thanks to a lit­tle testos­terone, accord­ing to a new study.

It’s not uncom­mon for lady lemurs to bite their mates, snatch a piece of fruit from their hands, whack them in the head or shove them out of prime sleep­ing spots. Females mark their ter­ri­to­ries with dis­tinc­tive scents just as often as the males do. Males often don’t take their share of a meal until the females have had their fill.

It’s strong evi­dence that hor­mones are play­ing a role
Joseph Petty, Depart­ment of Evo­lu­tion­ary Anthro­pol­ogy, Duke Uni­ver­sity, Durham, USA »


If a male lemur is enjoy­ing a patch of sun­light, for exam­ple, a female is likely to push him aside and take his spot,” said Joseph Petty, most recently a doc­toral stu­dent at Duke University.

Most female mam­mals that get their way over males are well-​armed to be the bul­lies. Dom­i­nant female spot­ted hye­nas, for exam­ple, are big­ger and heav­ier than males. But female dom­i­nance in lemurs remains a puz­zle. Female lemurs are no big­ger than males, and they don’t have antlers or big­ger fangs to give them a phys­i­cal edge over their mates.

Researchers at the Duke Lemur Cen­ter say females have sig­nif­i­cantly lower testos­terone lev­els than the males across the board. But when they com­pared six lemur species, they found that females of some species have higher testos­terone lev­els than others.

Petty and Duke pro­fes­sor of evo­lu­tion­ary anthro­pol­ogy Chris­tine Drea exam­ined behav­iour and hor­mone pro­files in nearly 30 ani­mals rep­re­sent­ing six closely-​related species in the genus Eule­mur. In four of the species, females are at the top of the peck­ing order, and in the other two species the sexes have equal sta­tus. The find­ings have been pub­lished on 7 May in open access jour­nal Sci­en­tific Reports.

The dom­i­nant females had sig­nif­i­cantly higher male hor­mone lev­els than the females from the two more egal­i­tar­ian species.

It’s strong evi­dence that hor­mones are play­ing a role,” Petty said.

Lemurs and lorises split off from the rest of the pri­mate fam­ily tree more than 60 mil­lion years ago, but the two species of egal­i­tar­ian lemurs didn’t evolve until much more recently, within the last 2 mil­lion years.

It could be that females are more sen­si­tive to the effects of testos­terone than males, stim­u­lat­ing aggres­sive behav­iour even though males still have more of the hor­mone, Petty said.



(Source: Duke­TO­DAY news release, 12.05.2015)


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