Wednesday, 25 April, 2001, 18:44 GMT 19:44 UK
Do Women Use Deceit To Keep Men Monogamous? Security for women, Sex
for men Are Basis for Monogamy
To love, honour and deceive
By BBC News Online correspondent Mark Ward
Long-term relationships are fundamentally dishonest. And it's all the
fault of females.
Scientists claim that monogamous relationships among many species,
including humans, only persist because females have found a way to
disguise whether they are fertile.
The researchers claim that by offering sex anytime, but no clues as
to whether they will conceive, females trick males into hanging round
for a long time.
The evolution of this deception is the only reason that monogamy has
developed.
Sexual deception
New Scientist reports that two zoologists claim to have uncovered the
dishonest heart of every faithful relationship.
Magnus Enquist of Stockholm University and colleague Miguel Girones
from the Netherlands Institute of Ecology have been modelling the
development of monogamous relationships and claim that the state only
develops when females start deceiving males about their fertility.
In many species females often advertise their fertility with visual
or chemical cues and, as a result, only suffer the amorous attentions of
males when they are likely to conceive.
They typically avoid too much sex because it takes energy and leaves
them at the risk of contracting disease.
This behaviour also helps males decide who to mate with, and when
they can move on and try to spread their genes elsewhere.
In many other species, such as humans, birds and porcupines, females
hide their fertility and so keep males hanging round on the off-chance
that they will conceive.
Roguish behaviour
This deception also discourages males from seeking other mates
because they are just as likely to be fertile as the female the male has
shacked up with claims Mr Enquist.
The pair tested their theory in a mathematical model and found that
males only stopped their roguish bachelor lifestyle when females start
hiding their fertility.
"Classical explanations of sexual behaviour always focus on the
male," Mr Enquist told New Scientist.
"But this gives stronger focus on the woman."
Source:
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1296000/1296607.stm
Wednesday April 25, 2001 4:03 PM ET
Women stay monogamous for security, Men stay for sex
LONDON (Reuter) - Women stay in monogamous relationships for security
and men stay in them for sex, a science journal said on Wednesday.
``It's a cynical view of human relationships, but researchers now say
it is the driving force behind the evolution of monogamy -- and women
started it,'' New Scientist magazine said.
In most species, females only have sex when they are fertile and males
know through visual and chemical cues when the time is right. When it is
not, males look elsewhere.
But in birds, porcupines and humans, females have sex whether they are
fertile or not, making it more likely that the males will stick around
because fertility is no longer an issue.
``There is a search cost. It takes some time to find a female,'' Magnus
Enquist of Stockholm University told the magazine.
Enquist and his colleague Miguel Girones of the Netherlands Institute
of Ecology in Nieuwersluis developed a mathematical model to test their
theory. They found that monogamy is often the top choice when fertility is
hidden, even among males who are used to having many partners.
``Classical explanations of sexual behavior always focus on the male.
But this gives stronger focus on the woman,'' said Enquist.
Sex, lies and monogamy
At the heart of all long-term relationships lies a
fundamental deception - disguised fertility
Exclusive from New Scientist magazine
Women only stay with men for security, and men only
stay with women for sex. It's a cynical view of human relationships, but
researchers now say it is the driving force behind the evolution of
monogamy - and women started it. By offering sex all the time, females
in monogamous species disguise whether they are fertile and trick males
into sticking around.
In most species, females only have sex when they are
fertile. This is because sex takes energy, and carries the risk of
disease. But it also means males can easily tell which females are
fertile, so they don't waste time on mates that won't get pregnant.
Indeed, males usually give females no help in raising
their offspring. "The male strategy is to stay with the female for as
long as she is fertile, and then to leave," says zoologist Magnus
Enquist of Stockholm University.
But in some species, including birds, porcupines and
humans, the girls have wised up. By cutting down on visual and chemical
cues, and by having sex all the time, they stop males from telling
whether they are fertile. "The male has no cue," says Enquist. "All he
can see is the behaviour of the female."
Once males are blind to a female's condition, he
says, it's no longer worth their while chasing lots of partners, because
the one they're with is as likely to be fertile as any other. "There is
a search cost. It takes some time to find a female."
Female focus
Although this idea makes intuitive sense, until now
it was a mystery whether the trick works. Normally, a male choosing a
stable relationship over a philandering lifestyle would have fewer
offspring, putting him at an evolutionary disadvantage. Would women
hiding their fertility by offering sex continuously be enough to tip the
balance?
Enquist and his colleague Miguel Girones from the
Netherlands Institute of Ecology in Nieuwersluis decided to investigate.
They created a mathematical model to test the theory, and found that
under certain conditions, monogamy is the preferred option. Even in a
population where males were used to having many partners, if females
started to conceal their fertility, the males settled down into
long-term partnerships.
"Classical explanations of sexual behaviour always
focus on the male," says Enquist. "But this gives stronger focus on the
woman."
Evolutionary biologist Anders Møller from the CNRS,
France's centre for scientific research in Paris, agrees. "This is
driven by females," he says. "When ovulation becomes concealed, the
males stay with the females longer."
Best of the bunch
But animal behaviour expert Mike Siva-Jothy of
Sheffield University argues that tricking males into being monogamous
isn't the only reason for females' high sex drive. Having lots of sex
with lots of different males might ensure that at least some of their
offspring were fathered by good-quality mates.
Although this idea doesn't fit with the traditional
view of monogamous societies, Siva-Jothy points out that even in species
where pairs bond for life, the females cheat. "When avian biologists
went out and looked at the DNA profiles of the offspring, they found
that everyone was having a romping time," he says.
But so long as females can fool males into thinking
they are being faithful, their strategy of hidden fertility will still
work. "They have to be cryptic because they don't want their partner to
find out," says Siva-Jothy.
Source:
http://www.newscientist.com/
In relationships men want sex, and women security
By Robert Uhlig
Telegraph Technology Correspondent
UK Daily Telegraph
AT the heart of all long-term relationships
lies a fundamental deception, scientists say today. Women stay with men
for security, and men remain with women for sex.
Researchers in Holland and Sweden say in New Scientist that the
deception is the driving force behind the evolution of monogamy. By
offering sex all the time, they say, females in monogamous species, such
as humans, birds and porcupines, disguise whether they are fertile and
trick males into staying.
The result is that men haplessly become monogamous, unable to move on
to a new partner because they cannot determine whether their most recent
coupling has resulted in pregnancy. Although it intuitively makes sense,
scientists had no explanation why men were mainly monogamous, whereas
males in most species seek to mate with as many females as possible to
maximise the number of children they father.
Usually, a male choosing a stable relationship over a philandering
lifestyle would have fewer offspring, putting him at an evolutionary
disadvantage. Now, Magnus Enquist, a zoologist at Stockholm University,
and Miguel Girones of the Netherlands Institute of Ecology have made a
mathematical model proving that under certain conditions monogamy makes
more sense than sleeping around.
Prof EnquistIn said most species, females only had sex when they were
fertile because it took energy and risked disease. "The male strategy is
to stay with the female for as long as she is fertile, then leave." This
meant that males could easily tell which females were fertile to avoid
wasting time on mates that would not conceive.
Males usually gave females no help in raising their offspring. But
humans, birds and porcupines were more sophisticated, Prof Enquist said,
because the females did not use visual or chemical clues to indicate when
they were fertile. Instead, women had sex at any time to prevent men from
telling when they might be fertile.
Once males were blind to a female's condition it was no longer worth
their while chasing lots of partners, because the one they were with was
as likely to be fertile as any other.
Source:
http://www.telegraph.co.uk/
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