452 Part V Biological/Evolutionary Theories
but it does not fit into any of the Big Five categories. These ratings of animal person-
ality were made by one of two behavioral observation techniques: either by animal
trainers who had extensive knowledge of the individual animals or by trained observ-
ers with no history with the animals but who were trained until they could reliably
evaluate the dimensions in question.
It may not surprise you that primates and other mammals tend to share the
largest number of personality traits with humans (Weinstein et al., 2008). For
instance, chimpanzees, our closest relative, share with humans a distinct “conscien-
tiousness” dimension. Such a finding suggests that conscientiousness—which
involves impulse control and therefore requires highly developed brain regions capa-
ble of controlling impulses—is the most recently evolved personality trait. Thus, with
the exception of chimps and horses, animals other than humans do not possess the
required brain structures to control impulse and organize and plan their activities in
advance. Even with chimps, the conscientiousness dimension was somewhat nar-
rowly defined as lack of attention, goal directedness, and disorganized behavior.
It may be surprising, however, to see wild birds, fish, and even octopus on a
list of animals that possess humanlike personality traits. For instance, in a study of
a European bird resembling a chickadee, when researchers placed a foreign object,
such as a battery or a Pink Panther doll, into the cage, some birds were consistently
curious and explored the novel object while others consistently withdrew and avoided
the object (Zimmer, 2005; cf. Dingemanse et al., 2002). The researchers called these
differences in birds “bold” and “shy.” These differences are much like those psy-
chologists observe when they place an infant in a room with a stranger. Approach–
boldness and shyness–avoidance are also dimensions of human temperament.Most animals, including a chickadee, have unique and stable ways of behaving—in other words, they
have personality. © NPS Photo by Jim Peaco