Encyclopedia of Evolution.pdf - Online Reading Center

altruism
which the animal is not closely related. Reciprocal altruism
will not work unless there is a minimal level of intelligence.
This is because reciprocal altruism is susceptible to cheaters.
There must be some punishment for the individual that keeps
all its resources while accepting the help of others. The other
animals need to have enough intelligence to remember who
the cheaters are. This could be one of the major contributing
factors in the evolution of human language and human
intelligence. Evolutionary biologist Robin Dunbar suggests
that language evolved largely because it allowed humans to
keep track of the intricacies of social structure, which would
include the ostracism of cheaters.
In animal species with strong social hierarchies, the subordinate
males receive no benefit for being altruistic toward
the dominant males. Altruism between social classes conveys
no benefit in those species. The males may, however, benefit
greatly from carrying out acts of reciprocal altruism that win
allies from their social peers. Because of the need both for
paying back the altruism and for punishing cheaters, reciprocal
altruism works best in animal species that are intelligent,
social, and long-lived.
Indirect Reciprocity
Neither kin selection nor reciprocal altruism can explain
altruism toward individuals who are unlikely or unable to
reciprocate. While such altruism is rare in nonhuman species,
it is very common among humans. Evolutionary biologist
Geoffrey Miller points out that, in modern human charities,
the recipient is often indigent and unable to reciprocate, and
the recipient seldom knows who the donor is anyway. The
donors often are not interested in the efficiency of resource
transfer to the recipient. It would be much more efficient if
a rich person continued to earn money, then donated that
money, rather than working the equivalent number of hours
in a soup kitchen. What, then, could be an evolutionary
explanation for this kind of altruism?
The key to this kind of altruism may be whether or not
another animal is observing it. The altruist can obtain greater
social stature by being altruistic toward individuals that are
unrelated or that cannot repay. Mathematicians Karl Sigmund
and Martin Nowak have produced calculations that
demonstrate this advantage. Human donations of time and/or
money to charities, says Geoffrey Miller, more closely resemble
a display of wealth than a calculated plot to get reciprocal
benefits. Altruism, like conspicuous consumption, may
constitute a message to the population at large. Conspicuous
charity proclaims, “I am rich enough to give away some of
my resources. This tells you that I am not only rich but also
that I am a good person.” Conspicuous consumption tells the
observers only the first of those two things. The reputation
of being a good person might yield enough social benefits to
compensate for the cost of the altruism.
In particular, the altruist may gain advantages in mate
choice. sexual selection could favor a conspicuous display
of altruism, whether through charity or through a heroic deed
to benefit the community. It is usually the males that display
and the females that choose. Although among humans sexual
selection has been more mutual, it is still the males who show
off, and the females who choose, more often than the other
way around. Conspicuous altruism is not merely showing
off; it is actually useful information to the individual (usually
the woman) making the choice of a mate: Such a man
must have good resources and must be a good person who
will be good to her. Displays of altruism need to be excessive,
or prolonged, or both, in order for the woman to know
the man is not faking it. Geoffrey Miller uses the example of
Ebenezer Scrooge, the character in a novel by British writer
Charles Dickens. Before his transformation, Scrooge not only
did not participate in kin selection (he was not generous to
his nephew) or in reciprocal altruism (he was not generous to
Bob Cratchett), but also it is no surprise that he was single.
Sexual selection can, and routinely does, produce adaptations
that are costly to the individual, whether it is human altruism
or the tail of a bird of paradise. Miller uses sexual selection
as an explanation not only of the peculiarly human excesses
of altruism but all aspects of human intelligence (see intelligence,
evolution of).
Because altruism can provide fitness benefits, natural
selection has also favored the evolution of emotions that
reinforce altruism. Altruism feels good, in a number of ways,
including feelings of satisfaction for being altruistic, gratitude
toward donors, and rage toward cheaters. Neurobiologists
have measured brain activity in human subjects involved in
simulated situations of cooperation. They found that altruistic
cooperation activated the same brain regions (such as the
anteroventral striatum, also known as the pleasure center)
as cocaine, beautiful faces, good food, and other pleasures.
They also found this response when the subjects participated
in sweet revenge against cheaters. The idea that the enjoyment
of altruism has a natural basis is not new. American
president Thomas Jefferson wrote in a letter to John Law in
1814, “These good acts give pleasure, but how it happens
that they give us pleasure? Because nature hath implanted in
our breasts a love of others, a sense of duty to them, a moral
instinct, in short, which prompts us irresistibly to feel and to
succor their distresses.”
Evolution can therefore explain the tendency toward
altruism in three ways: kin selection, reciprocal altruism, and
indirect reciprocity. Since it is the proclivity, rather than the
act itself, which evolution explains, humans can perform individual
acts of self-sacrifice that yield no fitness benefit. But if
such acts were common, the tendency to perform them would
be selected against. A person can sacrifice herself or himself
in a totally unselfish fashion—and there are numerous examples
of such saints and heroes—because the behavior pattern
evolved in the human species as a result of people sacrificing
themselves in a selfish fashion.
Evolutionary altruism has also influenced the evolution of
ethical systems (see evolutionary ethics). Humans not only
behave altruistically but believe that this is the right way to
act. Evolutionary ethicist Michael Shermer indicates that, during
the course of human evolution, feelings of affiliation with
others and affection for others have evolved as reinforcements
of altruism, first through kin selection within extended families
and then through reciprocal altruism within communities.
These feelings, being the product of natural selection, have a