20
percent
fraction of day some
primates spend on
reciprocal grooming
90
percent
female vervet monkeys
(without infants) that
reciprocate grooming
9
percent
female vervets
(with infants) that
reciprocate grooming
Will groom mom
for baby cuddles
market forces govern infant’s
value within monkey groups
By Susan Milius
“Do my hair before you touch my baby” is
the rule among mother vervet monkeys
and sooty mangabeys when it comes to
letting a neighbor snuggle their infants.
As in some other primates, monkey
babies attract crowds of females eager to
touch, hold and make silly lip-smacking
noises at the little ones, says primatologist Cécile Fruteau of Tilburg University
in the Netherlands. Her novel study of
infant-touching etiquette in the vervets
and mangabeys adds them to the short
list of animals known to have “
markets” for baby fondling: Moms must be
groomed for a sufficient time before they
let the groomer touch the baby.
What makes this exchange a market is
the way sufficient grooming time changes
with the baby supply, Fruteau and her colleagues explain in a paper posted online in
Animal Behaviour . The price for access to
a group’s only infant, measured in grooming time for mom, fell when the number
of little cuties available for cuddling rose.
Price is sensitive to other variables as
well, says Fruteau, who documented for
the first time that infant age makes a difference in how much grooming the baby
attracts to mom. Newborns earn their
mothers the longest grooming sessions.
One newborn mangabey, for example,
the only baby in its group at the time,
earned about 10 minutes of fur cleaning
and combing for its mom. In contrast,
another lone baby didn’t even earn four
minutes of grooming once it had reached
the advanced age of almost 3 months.
Grooming time also correlated with
access to vervet babies but not with fondling time or the degree of familiarity
allowed. With enough grooming, moms
permitted pretty much any female in
their group to at least touch or sniff the
baby. But it was mostly females with a
history of grooming mom who could
actually hold the baby.
“Prices” for a baby encounter also
varied with rank, as in other infant-handling markets, Fruteau says. A female
ranking lower in the group hierarchy of
either species had to groom longer for
access than a high-ranked monkey did.
Grooming-for-cooing trades have also
been reported in chacma baboons and
long-tailed macaques. In spider monkeys,
the currency is hugging, not grooming.
Comparisons with markets can cer-
In South Africa, a baby vervet monkey
peeks out from mom’s embrace. Other
females must pay to play, grooming
mom for access to her infant.
tainly be useful, says primatologist
Rebecca E. Frank of Los Angeles Valley
College in Valley Glen, Calif., “but it just
leaves some aspects of female exchange
unexplained.” In her study of olive
baboons, about two-thirds of grooming encounters, even without babies
involved, don’t get promptly or obviously
reciprocated. These partners appear to
have long-term relationships that don’t
require immediate settling of accounts.
It remains unclear why babies stir such
urges to fondle, Fruteau says. For vervets
and mangabeys that’s largely a female urge.
Males interact more with older kids.
Slimy net foils biting pests
if you were to find yourself in the jungle without a mosquito
net, slathering yourself in snot might be a good course of
action. it works for fish: australian scientists found that some
coral reef fish are protected from biting isopods, a marine
equivalent of mosquitoes, by the blob of mucus the fish
don each night. it wasn’t clear how the coat served certain
parrot fish (shown) and wrasses. But when a university of
Queensland team put tiny parasitic isopods —bloodsucking
crustaceans closely related to lice—into tubs with parrot fish,
only 10 percent of fish with intact mucus cocoons had bites,
versus 94 percent of fish without cocoons. making the cocoon
is an efficient protection strategy, costing a mere 2. 5 percent
of the fishes’ daily energy budget, the researchers report
online november 17 in Biology Letters. — Rachel Ehrenberg
www.sciencenews.org
december 4, 2010 | science news | 9
