By Michael Alan Park, Ph.D
.
Central Connecticut State University
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written consent of McGraw-Hill Education.
McGraw-Hill
Chapter 7
Reproduction: The Sexual Primate
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written consent of McGraw-Hill Education.
7-2
As You Read, Consider:

How does human sexual behavior differ from that of most mammals?

How did this difference evolve?

What are the psychological and social implications of ‘sexual consciousness’ in humans?

How do human males and females differ, and how might these differences be explained
evolutionarily?
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How does the role of sex differ for bonobos compared to human society?
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In what ways does bonobo sexual behavior offer insight in the evolution of human sexuality?

What is the difference between sex and gender?

How do folk taxonomies differ in other cultures concerning sex and gender categories? What
are some examples?

How might our sexual behavior have influenced some of our cultural/social institutions?
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7-3
Sex and Human Evolution
In most mammals, sexual activity takes place only when it can do
what it’s supposed to do- make baby mammals. Sex is geared to the
reproductive cycle of the female, and eggs can only be fertilized at
certain intervals.
 Egg maturation (‘ovulation’) has two results—hormonal changes make
females sexually receptive to males, and olfactory or visual signals are
sent to stimulate the males. Females are in estrus. This is true for most
primates.
 Humans have nondetectable ovulation. They have replaced
unconscious, innate sexual signals with sexual consciousness.
Sexuality has become part of our conscious thought.
 Sexual expression in humans takes the form of individual
personalities, and respond sexually and according to culturally
determined standards of behavior and attractiveness (personal
appearance, intelligence, clothing styles, athleticism, advertising, etc.).

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Sex and Human Evolution
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No absolute difference exists between human and other animal’s expression of
sexuality. Bonobos and chimps both express a degree of sexual consciousness.
Sex occurs on a conscious level in both and is not used for reproduction alone
in either species.
Bonobo sexual behavior may shed light on the theory of the evolution in
humans of continual receptivity and conscious sexuality. Protohominid males
may have been involved in the raising of offspring within a peaceful,
cooperative, group, and allowed females to raise more offspring.
Sexual interest and conscious social interaction strengthened psychological,
personal commitments of males and females and was related to reproductive
success.
Natural selection extended sexual receptivity by concealing ovulation and
linking sexual behaviors directly with the conscious parts of the brain. The
human sexual pattern helped provide additional motivation for the
cooperation needed to share resources, strengthen the group, and successfully
raise future generations.
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Definitions
 Ovulation: The period when an egg cell
matures and is capable of being fertilized.
 Estrus: In nonhuman mammals, the period of
female fertility or the signals indicating this
condition.
 Olfactory: Referring to the sense of smell.
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7-6
The Importance of
Development and Child Care

Human infants are born earlier in their development than other
primate infants because bipedalism produces a pelvis that makes
childbirth more stressful.

After birth, the larger brain of humans simply take longer to
develop, so the period of dependency on the parents is longer.

Anthropologist Sarah Blaffer Hrdy hypothesizes that alloparenting,
or the shared caring and provisioning of the young by other
group members, became a necessity at a time when more, and
more varied, food was required to supply larger bodies and
brains.

This would set the stage for the mutual cooperation among our
families and societies.
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7-7
Vive La Différence

All sexually reproducing species display differences between the
two sexes; The sexes need different anatomical features for their
respective reproductive functions. This is referred to as sexual
dimorphism.

Human males and females differ at the genetic level. The X
chromosome is the female chromosome, and larger that the Y
male chromosome. The X carries genes for nonsexually related
traits as well. The Y chromosome appears to carry only genes
related to male sexual characteristics. Females have twenty-three
pairs, including a pair of X chromosomes. Males have twentythree pairs, including the twentieth-third pair with an X
chromosome from his mother and a Y chromosome from his
father.
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Vive La Différence

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Human males are generally larger and more heavily muscled that females.
They are like the ape and some of the monkeys. Differences are less
pronounced in humans.
Dimorphism is more pronounced in more terrestrial primates like
baboons. This is likely for purposes of group protection and may represent
an earlier human adaptation in Africa. Female pelvises are wider for
carrying and giving birth to children.
The male heart and lungs are more robust, but males are more susceptible
to disease. Speech disorders, ulcers, vision hearing, and skin problems are
greater as well.
Females mature faster, have more body fat, and exhibit earlier puberty.
They have less disease and recover faster when they do. Females are more
sensitive to touch and pain and sound.
Dimorphic features are not completely understood. There is overlap in
range of variation of traits. Tendencies suggest an African terrestrial
adaptive explanation.
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7-9
Vive La Différence
 Males have more facial and body hair than females
and may be related to individual identity
 Lips and lip color may be another indicator and
related to signaling arousal.
 The location of human body hair (ancillary and pubic
regions) may be related to courtship and mating
related to olfactory signals of estrus
 These traits and attitudes about them are manipulated
by culture.
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7-10
Definitions
 Sexual Dimorphism: Physical differences
between the sexes of a species not related to
reproductive functions.
 Aprcrine Glands: Specialized sweat glands that
secrete an odorous substance thought to be
related to sexual stimulation
 Pheromones: A chemical substance secreted by
an animal that conveys information and
stimulates behavioral responses.
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7-11
Sex and Gender
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Male and female are two biological categories that are objectively real and
common to all human groups. As these two categories are incorporated
into various cultural systems, however, differences arise.
The identity and role of males and females under different cultural
systems vary depending on the nature of those systems. Cultural
interpretations of sex categories is referred to as gender. There is a great
deal of variation in gender identity and gender roles cross-culturally.
Changes in gender roles in the last 100 years in the US illustrate this.
Hutterite gender roles have remained static.
Folk Taxonomies represent the relationship among culturally constructed
sets of categories. Gender is an example. A society orders its world in
ways that reflect its particular cultural needs as an objective reality as its
people see and understand it.
Comparison of the Fore of Papua, New Guinea, the hijras of India, and
the bedarche among traditional Native American cultures each provide
illustrations of differences in folk taxonomies.
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7-12
Definitions
 Folk Taxonomy: A system of classification
based on the relationships among cultural
categories for important items and ideas.
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7-13
Sex and Cultural Institutions
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Cultural universals are behavior patterns found in all societies. They are
among the most interesting (and sometimes the most puzzling) of cultural
phenomena.
Humans have the ability to invent behaviors and change them at will, and
most behaviors show a good deal of variation. Marriage and the incest taboo
are two examples.
Marriage exists with a great deal of variability across cultures. Its
universality can be explained in much the same way as sexual
dimorphism—a biological origin later translated into a variety of cultural
interpretations.
The incest taboo is a part of every culture, and prohibits sex and marriage
within the nuclear family. The genetic defect rationale and avoidance of
sexual conflicts within the nuclear family are a possible reason for
universality, but its more likely related to also a biological basis
underneath its cultural expression—related to close proximity and
familiarity to ‘turn off ’ sexual attraction.
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Definitions
 Marriage: A set of cultural rules fro bringing
men and women together to create a family
unit and for defining their behavior toward one
another, their children, and society.
 Nuclear Family: The family unit made up of
parents and their children.
 Incest Taboo: A cultural rule that prohibits
sexual intercourse or marriage between
persons defined as being closely related.
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7-15
Questions for Further
Thought
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Examples of the conscious and cultural dimensions of sexual behavior in
humans abound. As an experiment, the next time you watch TV for an
extended period, keep track of how many advertisements, out of all you see, use
sex as a “hook.” How many of these are for products that have nothing to do
with sex ?
For better or worse, TV is a reflection of our culture. Watch a current TV show,
perhaps a sitcom. Then find a rerun of a sitcom from maybe the 70s, 60s, or
even 50s.
Read “The Five Sexes” and “The Five Sexes Revisited” by Anne FaustoSterling. What do you think about so-called “intersexes,” people who do not
unambiguously fit either the male or female category? Are they “abnormal,” or
do they, as Fausto-Sterling suggests, deserve their own category or categories?
If so, how would this affect various aspects of our society?
Issues of sexual orientation have been very much in the news lately. Consider
the issue of so-called “gay marriage.” Does the information in this chapter shed
any light on this contentious question? Has it perhaps changed your mind on
the matter?
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written consent of McGraw-Hill Education.
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