“... maybe you don’t want to be on contraceptives
when you’re picking your mate.”— Su SAn JenkS
lemurs on the pill make less scents
By Susan Milius
Putting a female lemur on birth
control turns her normally
informative scents to nonsense.
Doses of Depo-Provera, a
human contraceptive also used
in zoos and animal research,
shift the odor secretions of
female lemurs so dramatically
that their scents no longer give
clear cues to kinship, identity
and genetic quality, says study
coauthor Christine Drea of
Duke University in Durham,
N.C. A female lemur whose hormones
are disrupted by contraceptives may
have real trouble attracting a compatible mate, Drea reported July 26.
Drea and her colleagues have identified more than 300 compounds in
the scent secretions of female lemurs.
Glands on the forelimbs, tail and other
ring-tailed lemurs (shown at the Duke university
lemur center) communicate using scent.
parts of the body secrete chemical cues
that the lemurs rub onto branches or
other community bulletin boards where
neighbors sniff out the news.
Working with 12 adult female ring-
tailed lemurs at the Duke Lemur Cen-
ter, Drea and colleagues studied female
genital odors by analyzing secretions
chemically and observing animals’ sniff-
ing behaviors. The researchers collected
scents before and after giving the lemurs
a form of the hormone progestin called
medroxyprogesterone acetate, or MPA,
sold as Depo-Provera. Details of the
study were published online July 28 in
the Proceedings of the Royal Society B.
natural male
enhancement
ducks’ penises grow longer
with increased competition
New measurements find that the length
of a duck’s penis depends on the company he keeps. And in this case, it’s his
fellow males who make the difference.
A drake’s penis substantially wastes
away at the end of one breeding season
and then regrows as the next season
begins. Among lesser scaup and ruddy
ducks, the regrowth varies in length or
timing depending on whether males have
to compete with a bunch of other guys,
said Patricia Brennan of Yale University.
Her new measurements offer the first
evidence in vertebrates that social circumstances influence penis growth, she
reported July 29.
In many birds, males don’t grow special-
ized organs to deliver sperm. But ducks’
Among the scaup, males com-
peting in groups grew penises
15 percent longer, and some-
times up to 25 percent longer,
than drakes with no mating
rivals, Brennan reported.
Among ruddies, penis length
2 cm
did not differ overall between males in
competitive crowds and those in lucky
privacy. What did differ was timing.
In the competitive groups, a few big
males grew prodigious organs. Other
males grew more moderate
penises, which started wasting
away weeks earlier than those of
dominant males or males with
no competition.
In a crowd, a ho-hum male
apparently doesn’t bother sustaining a big investment in tissue that’s not going to pay off.
“Elegant,” said evolutionary
ecologist Maydianne Andrade
of the University of Toronto
Scarborough. The new experimental results show that ducks
“are essentially engineering
their own phallus in response
to social challenges.”
the corkscrew-
shaped penis of
a ruddy duck.
