with the environment to reproduce and pass their inherited characteristics on
to their offspring. The net result over many generations is the evolution ofspecies-specific features. Through the process of natural selection, those spe-
cies developing features that help them survive prosper, and those failing to
develop these features die out. In many cases, physical features evolve because
they provide solutions to a serious threat to species ’survival. For example, in
humans, the problem of disease was resolved by the evolution of an immunesystem, and the potential problem of bleeding to death when cut or woundedled to the evolution of blood clotting (D. M. Buss, 1991). This is not to say
that these features were created because they were needed. Rather, the theory
of evolution maintains that because of these changes our species was better
prepared to survive.
According to evolutionary personality theory, just as the natural selection
process has led to the evolution of certain physical characteristics in humans,this process is also responsible for what are called psychological mechanisms .
These psychological mechanisms are characteristically human functions that
allow us to deal effectively with common human problems or needs. Throughthe process of natural selection, mechanisms that increased the chances of
human survival and reproduction have been retained, and those that failed to
meet the challenges to survival have not.
Psychologists have identified a large number of these mechanisms. For ex-
ample, most humans have an innate fear of strangers. Evolutionary personal-ity psychologists argue that this fear evolved to meet the problem of attack by
those not belonging to the group or tribe (D. M. Buss, 1991). Similarly, anger
might have assisted our ancestors in such survival behaviors as asserting
authority and overcoming enemies (McGuire & Troisi, 1990). Thus it makes
sense that anger is a common human characteristic. Some psychologists argue
that humans have an innate need to belong to groups and form attachments
(Baumeister & Leary, 1995). It is not difficult to imagine how a species thatworked together would survive better than a species that did not. But whereas
the survival function of some human characteristics may be easy to explain,
the advantages of other psychological mechanisms might not be so obvious.We turn next to an example of one such mechanism.
Anxiety and Social Exclusion
Evolutionary personality theory maintains that human characteristics such as
anxiety evolved because they proved beneficial to the survival of our ances-
tors. But how can this be? Anxiety is an unpleasant emotional state, some-thing a normally functioning person would prefer to avoid. Moreover, anxiety
is almost always problematic. It interferes with our ability to learn new tasks,
remember information, perform sexually, and so on. How can something asdisruptive as anxiety help the species?
We can answer this question by looking at what causes anxiety. Some
psychologists have argued that one of the primary causes of anxiety is socialexclusion (Baumeister & Tice, 1990). These investigators propose that all
humans have a strong need to belong to groups and to be in relationships.
Consequently, when we experience exclusion or rejection from social groups, weEvolutionary Personality Psychology 237