Chapter 14 The Major Motives of Life: Food, Love, Sex, and work 499that might explain why the males in some of these
species evolved from solitary living to monogamy.
The found that monogamy emerged in condi-
tions where females live in wide ranges that do
not overlap, so females are scarce and males can’t
prevent other males from mating with them.
Therefore, it became a better strategy to stay put
and look after their offspring (Lukas & Clutton-
Brock, 2013).
Further, contemporary differences in sexual
behaviors and attitudes are not as large or univer-
sal as the evolutionary stereotype would predict.
In Western nations, as gender roles have become
more egalitarian, men and women have become
more alike (Petersen & Hyde, 2010; Wells &
Twenge, 2005). Today, straight women are just as
likely as men to say they would accept a sexual offer
from a great-looking person (or an unattractive fa-
mous person, thus explaining the groupie phenom-
enon). And both sexes are equally likely to say they
would accept sex with friends or casual hook-ups
who they think will be great lovers and give them
a “positive sexual experience” (Conley et al., 2011).2
Cultural variation. Human sexual behavior is
amazingly varied and changeable across time
and place. Cultures range from those in which
women have many children to those in which
they have very few, from those in which men are
intimately involved in child rearing to those in
which they take no part at all, from those in which
women may have many lovers to those in which
women may be killed for having sex outside oftheorists, have challenged this conclusion on con-
ceptual and methodological grounds:
Watch the Video What’s In It For Me? The
Dating Game at MyPsychLab1
Stereotypes versus actual behavior. The behav-
ior of humans and other animals often fails
to conform to the stereotyped images of sexu-
ally promiscuous males and coy, choosy females
(Barash & Lipton, 2001; Birkhead, 2001; Fausto-
Sterling, 1997; Hrdy, 1994; Roughgarden, 2004).
In many species of birds, fish, and mammals, in-
cluding human beings, females are sexually ardent
and often have many male partners. The female’s
sexual behavior does not seem to depend only on
the goal of becoming fertilized by the male, either:
Females have sex when they are not ovulating and
even when they are already pregnant.
Further, in many species, from penguins to
primates to the golden lion tamarind, males do
not just mate and run. They stick around, feed-
ing the infants, carrying them on their backs,
and protecting them against predators (Hrdy,
1988; Snowdon, 1997). Originally, evolutionary
biologists thought that male monogamy evolved
among some mammals as a tradeoff: The male
gives up the chance to fertilize many females for
the increased likelihood of his own offspring’s
survival. This may be the case in certain species.
But it is also possible that male involvement in
caring for offspring didn’t cause monogamy, but
resulted from it. Two scientists examined 2,545
species of mammals, searching for any factorsAh, father love! Evolutionary approaches to sex assume that males across species have only a
minimal investment in caring for offspring. But there are many exceptions, including male snow
monkeys and lions, who are doting dads.