Infidelity in the monkey world
November 24, 1998
Web posted at: 12:35 PM EST
By Environmental News Network staff
(ENN) -- Most animals, even those
previously believed to be staunchly
monogamous, engage in extra-marital
affairs, according to research published in
the Nov. 21 issue of the New Scientist.
"Even creatures once considered as paragons
of fidelity will indulge in a fling if the
situation is right," writes Robin Dumbar, a
professor of evolutionary psychology at the
University of Liverpool, England.
"The animal world, it turns out, is full of
examples of cuckoldry, cheating and even
divorce, by supposedly lifelong mates as
they try to overcome what I call the
monogamists' dilemma," writes Dumbar.
Dumbar cites various examples of infidelity,
including the South American marmoset and tamarin
monkeys where "divorce" rates can be as
high as a third of all pairs in a given year.
This situation is explained via a high rate in
female mortality, resulting in an excess of males.
According to Dumbar, with females in short supply,
a male who cannot secure a mate of his own
may become a "helper-at-the-nest" and help rear
offspring that are not his own.
In turn, the father of the offspring will take
advantage of the male helper's presence by going off
in search of another female because he will be able
to breed again sooner than if he waited for his
current mate to come back into breeding condition.
The helper then mates with the female when she
comes into estrus. "And the females seem
indifferent to their mate's behavior: so long as
they have a male to help with rearing the
offspring, they don't seem to mind too much who he
is," Dumbar writes.
Other reasons for infidelity cited by Dumbar
include females choosing a mate who may be a good
provider but not necessarily endowed with good
genes. She will allow this mate most of her
conceptions, as she needs a male to invest in her
offspring, but keep a few reserved for better
quality mates when she finds them.
Dumbar notes the research of Andre Dhondt at
Cornell University who found that females often
instigate divorce when new and better mating
possibilities come along.
Extra-marital affairs are also used to keep a
relationship strong. Playing on the emotional
landscape of jealousy, a female may play one male
off against another to prevent the pair-male
from straying off in search of other females.
"Animals, every bit as much as humans, make choices
about whom to pair with and for how
long, and those decisions are influenced in large
part by whether they will do better by staying
with the current partner, by moving from one
partner to another or by playing a more subtle kind
of game," writes Dumbar in conclusion.
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