Chapter 15 Buss: Evolutionary Theory of Personality 453Moreover, some researchers have begun to uncover the genetic foundation of
animal personality traits (van Oers & Mueller, 2010). For instance, using the QTL
technique we described above, researchers have found genetic locations of exploratory
behavior and risk-taking behavior in fish (Boehmler et al., 2007; Laine et al., 2014),
birds (Fidler et al., 2007), and dogs (Ito et al., 2004).
In sum, just as eyes, ears, brains, and thermoregulation are evolved solutions
and are shared between species and genera of animals, personality traits are shared
solutions and found in almost all animals from the invertebrates, fishes, reptiles,
birds, and mammals (including primates). The more similar the genus and species,
the more similar the system—and this holds for personality. The personality structure
of primates is more similar than that of mammals in general, which in turn is more
similar than birds or invertebrates. This evidence supports the view that personal-
ity traits evolved long before modern humans and have their origins in a common
ancestor millions of years ago.
Critique of Evolutionary Theory of Personality
Evolutionary psychology in general and evolutionary personality psychology in
particular have stimulated a lot of controversy but also a relatively large body of
empirical research. The field has its own scientific society (Human Behavior and
Evolutionary Society, HBES), and its own scientific journal, Evolution and Human
Behavior. The discipline also rests upon other scientific disciplines, such as evo-
lutionary biology, ethology, behavioral genetics, and neuroscience, so there is a
solid empirical foundation to the field. Similarly, a quick search on GoogleScholar
generated more than 34,000 articles for the joint term “evolutionary psychology.”
The same GoogleScholar search on “evolutionary personality psychology” pro-
duced 660 articles between 1990 and 2012.
To the question of whether evolutionary personality theory is falsifiable the
answer is complex. Evolutionary theory in general is difficult to falsify in the strict
sense of the word (Stamos, 1996). Many critics of evolutionary theory are quick to
point out that the central tenets of evolutionary theory are inherently non-falsifiable
and untestable because evolution is a past event and it would take at least thousands
of years to observe the outcome of evolution in animals. Moreover, they argue that
evolutionary psychology is mostly after the fact (post hoc) explanations for any
given phenomenon—in short, evolutionary psychology produces plausible “just-so
stories” and many different plausible stories can always be constructed to explain
an evolutionary outcome (Gould & Lewontin, 1979; Horgan, 1995).
Yet, other scholars have argued this is both somewhat inaccurate and also not
completely the point. Defenders of evolutionary theory, for instance, have pointed
out that defeating a theory by contrary facts (falsification) is not the only way that
science proceeds (Ellis & Ketelaar, 2000; Ketelaar & Ellis, 2000). An alternative
criterion for scientific progress is whether it generates novel predictions and expla-
nations. By this standard, evolutionary theory does quite well.
In terms of how well evolutionary theory of personality organizes known knowl-
edge, we would argue the theory rates quite highly. Evolutionary theory is very broad
and long-range in its scope and in that sense it provides a range of explanations