Free The Dangerous Passion: Why Jealousy Is as Necessary as Love and Sex by David M. Buss Page A

example, before consenting to sex,
or look for signs that the man is “playing the field,” such as how much his
attention is diverted from their conversation when an attractive woman walks
by. They might develop tests of a man’s commitment, such as asking that he
cancel watching the Monday night football game with his friends to attend to
her needs.
    As women developed the ability to detect deception, they imposed
selection pressure on men to become better deceivers. And so the
co-evolutionary spiral continues, with each increment in one sex producing
reciprocal evolutionary change in the other. Adaptations in one sex lead to
counter-adaptations in the other, and those in turn lead to further
counter-adaptations and counter-counter-adaptations. As long as the strategies
of the sexes are in some degree of conflict, this co-evolutionary spiral will
continue unabated. At the current moment in time, we are poised in the middle
of this spiral, with women being excellent detectors of deception, as indicated
by factors such as their superiority over men in decoding nonverbal signals.
Men, in turn, can be notoriously skilled at deceiving women.
    Jealousy provides the perfect example of the power of the
co-evolutionary spiral, and it starts with the evolution of love. Sustained
romantic bonds pose a special problem: how to defend against the possibility
that “poachers” lurk in the wings and might succeed in luring a partner away.
One popular song captured the essence of the poaching problem, albeit from a
man’s point of view: “When you’re in love with a beautiful woman, watch your
friends.” The more desirable your partner, the more intently interested
potential interlopers will be to intrude.
    Jealousy evolved as a primary defense, a co-evolved response to
threats of a partner’s infidelity and abandonment. It becomes activated
whenever a person perceives signs of defection—a strange scent, a sudden change
in sexual behavior, a suspicious absence. It gets triggered when a partner
holds eye contact with someone else for a split second too long, or when a
rival stands a tad too close to your loved one or suddenly seems fascinated by
the minutiae of his or her life. These signals do not inevitably mean that a
partner will stray, just as the annoying blare of a fire alarm does not
inevitably mean that a fire is blazing. Alarms may be false. But these signals
alert us to the possibility of infidelity, since they have been statistically
linked with relationship loss over the long course of human evolutionary
history.
    This is where co-evolution kicks in again. Jealousy, which gives
us sensitivity to signals of betrayal, produces partners who conceal their
defections and would-be poachers who conceal their interest in your mate. A
classic case of misdirection occurred in Vladimir Nabokov’s novel
Laughter
in the Dark
. The central character is a wealthy, respectable businessman
named Albinus, who pursues art and cinema as hobbies. After a long period of
fantasizing about it, Albinus leaves his wife and starts to live with his young
mistress, named Margo Peters. Unbeknownst to Albinus, Margo begins to scheme to
fleece him of his money. In time, Albinus hires an artist named Axel Rex to
indulge his fantasy for producing a new kind of movie. Albinus remains in the
dark about the fact that Rex and Margo had previously been lovers. Before long,
Margo and Rex resume their torrid affair. Axel Rex delights in carrying out the
deception right under Albinus’s nose. When Albinus begins to grow suspicious,
Rex uses an interesting ruse—he pretends to be gay. Margo joins Rex in the
deception, declaring her contempt for Rex’s feminine mannerisms. With these
deceptions in place, Margo and Rex succeed in allaying Albinus’s suspicions,
and Rex is allowed to become a common presence in their household while
cuckolding Albinus at every opportunity.
    Co-evolution continues. Concealment, which evolved as a response
to a partner’s