Does Dogs have Personality?
What is personality? And, can animals have personality?
Personality is a set of attributes--such as sociability, aggressiveness, and
willingness to please--that come together to form the social behavior of a
species. What makes personality interesting is the variation of its expression
among animals within a species, population, or social group. Scientists working
on social behavior of birds or mammals are often struck by differences in
personality among their study animals. This is particularly true of primates,
canids, parrots and their relatives, crows and their relatives, and dolphins,
but such variation can be found in a broad, and sometimes surprising, range of
animals.
If personality varies among animals within a species,
what function might this variation have? Variation may be the expression of
different strategies, as predicted by game theory. Within this hypothesis,
there are two possiblities. First, it may well be that success as a dominant
animal calls for a different personality than does success as a subordinate, and
expression of personality depends on status within the social group. In this
type of system, an animal's personality may vary, depending on the
circumstances. Second, personality may be fixed, genetically, for a given
animal, but it may vary among individuals because strategies differ in their
success, depending on environmental factors. If personality varies among
animals, but is genetically fixed for an individual, then the study of
personality lies within the realm of behavioral genetics.
Among non-human animals, personality is best known in
chimpanzees and domestic dogs. In chimpanzees, personality is generally thought
to be described by these variables (Weiss et al. 2000):
- Dominance
- Extraversion
- Dependability
- Emotional Stability
- Agreeableness
- Openness
The last five of these dimensions are thought to describe
human personality (Bouchard 1994); their presence in both chimps and humans can
be thought of as representing the shared evolutionary history of chimpanzees
and humans. In both humans and chimpanzees, these personality traits have
relatively high heritabilities and show virtually no effect of rearing
environment. Human twins who are separated at birth and reared in very
different environments show startling similarities in personality. In their
study of chimpanzees, Weiss et al (2000) found a particularly strong
heritability on social dominance, and weak heritabilities for the other
dimensions of chimp personality. As in human studies of personality, Weiss et
al. (2000) found little effect of environment (in this case, different zoos) on
personality.
In dogs, Svartberg and Forkman (2002) identified the main
variables describing personality:
- Playfulness
- Curiousity/fearlesness
- Desire to chase
- Sociability
- Aggressiveness
They suggest that the first four factors are all
influenced by a single "broad" personality dimension, with
aggressiveness working separately. This is, interestingly, quite parallel to
the role of dominance in chimpanzee personality. Wilsson and Sundgren
(1997)show that dog personalities have substantial heritable components,
although their study isn't strictly comparable to Svartberg and Forkman's
(2002) study, as they use different descriptors of personality.
In sum, personality in animals is real, measuable, and
seems to be strongly influenced by genes. Variability in personality is, in a
sense, genetic variability. This suggests that different personalities can be
successful and persist in evolutionary time; if only one personality type were
succcessful, natural selection would eliminate this variation.
Image Source: http://www.sxc.hu/photo/1394407
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