Encyclopedia of Evolution.pdf - Online Reading Center

social behavior
social behavior See altruism; behavior, evolution of.
Social Darwinism See eugenics.
sociobiology Sociobiology is the application of evolutionary
biology to human and other animal behavior. Charles
Darwin wrote of the relevance of evolution to understanding
human and other animal behavior (see Darwin, Charles),
but the formalization of sociobiology as a distinct science,
and the invention of the name, date from the 1975 book
by Edward O. Wilson (see Wilson, Edward O.). Wilson
explained the evolutionary basis of the behavior of a wide
range of different animals, then in the last chapter applied
these principles to humans. He expanded human sociobiology
into a best-selling 1978 book On Human Nature.
Wilson identified a number of human behaviors that
appear to be universal. If these behaviors were determined
entirely by the environment in which individuals developed
and on their personal decisions, they would be unlikely to be
universal. Wilson did not claim that environment and personal
decision had no effect on human behavior, but that
they did not influence them completely (see essay, “How
Much Do Genes Control Human Behavior?”). Wilson then
provided explanations of how each of those behaviors would
have proven beneficial to the fitness of humans, and therefore
would have been favored by natural selection (see
behavior, evolution of). The environment in which these
behaviors would have proven beneficial is not the modern
environment but the environment of evolutionary adaptedness,
during the hundred thousand years that Homo sapiens
existed prior to agriculture and civilization, and quite likely
the environments of earlier Homo and earlier hominin species.
These behaviors include:
• Incest avoidance. Human societies differ markedly in
reproductive systems, from (near) monogamy to the formation
of harems to (near) promiscuity. Societies differ markedly
in which behaviors they consider moral and immoral.
All human societies consider close consanguineous matings
(incest) to be immoral. The evolutionary benefit of the
“incest taboo” is that incest produces many offspring that
display detrimental genetic traits (see sex, evolution of).
• Recognition of discrete colors. Colors do not really exist.
Photons have a continuous range of wavelengths; wavelengths
between about 0.000015 inch (400 nm) and about
0.000028 inch (700 nm) are visible to humans. The recognition
of discrete colors results in part from the three kinds
of cones in the human retina (responding to wavelengths
humans recognize as red, green, and blue) and the interpretation
of nerve impulses by the human brain. Humans
of all cultures have brains that interpret very similar sets
of colors. Evolutionary advantages of color recognition
include the ability to recognize food sources and to use
color as a medium of cultural communication.
• Face pattern recognition. Humans of all cultures have
brains that recognize individual faces and do so on the
basis of mostly the same characteristics. The evolutionary
advantages include the ability to keep track of which
individual humans are friends and which are rivals within
a society.
• Facial expressions. Humans of all cultures produce and
respond to the same facial expressions in the same way,
including anger, terror, surprise, and happiness. Smiling is
not only universal but even individuals blind from birth,
and who could not possibly be imitating someone else,
smile. The advantages for social communication and cohesion
can hardly be overestimated.
• Specific sugar preferences. All human culture groups like
sugar and distinguish in a similar manner among different
kinds of sugar. Existing variation in sugar preference often
disappears when highly sugared modern food becomes
available to cultures to which it was previously unavailable.
Humans that liked sugar sought out and consumed
higher quality food than those that did not. As it turns out,
this universal trait is maladaptive under conditions of modern
civilization. Modern conditions began too recently to
influence human biological evolution.
• Fear of strangers (xenophobia). Every culture group has
feared and loathed people from other cultures. The advantage
that this provided was that people were willing to
fight against other cultures and acquire their land and
resources. The appreciation that the resulting conflicts are
counterproductive, and the growing sense that hatred of
people from other cultures is immoral, is a recent and cultural
development in the human species. The fear of strangers
within one’s own culture is also a recent phenomenon.
For most of the time the human species has existed, people
lived in small groups within which there were no strangers.
• Phobias. Phobias are fears that have no rational basis and
are seldom chosen or understood by the people who experience
them. Examples include the fear of spiders, snakes,
and heights. Wilson points out that these phobias correspond
to ancient, not modern, dangers. Phobias of guns,
for example, are not well documented. Spiders, snakes, and
falling out of trees (and later off of cliffs) were real and
continual dangers for the ancestors of modern humans.
The evolutionary advantage of phobias was that the person
could take immediate action without having to figure out,
or learn, the appropriate response—a behavior pattern particularly
valuable for young children.
Other researchers have added other apparently universal
behavior patterns. For example, men prefer women who are
young and pretty. Youth is an indicator that a woman has
a long period of potential reproduction ahead of her, and
beauty may be a reflection of health and therefore the ability
to resist parasites. These researchers also noticed that women
often prefer men who are older and as a result have more
resources. The difference in mate preferences between men
and women has been interpreted as an example of sexual
selection in which men maximize their fitness by inseminating
more females but women maximize their fitness by
access to more resources. Psychologists Leda Cosmides and
John Tooby say that humans are better able to figure out
social than logical situations, and have the ability to detect
nuances of character that may indicate dishonesty—and that