Does Your Dog 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):
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:
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.
Bouchard T J 1994 Genes, environment, and personality SCIENCE 264 (5166): 1700-1701
Svartberg K, Forkman B 2002 Personality traits in the domestic dog (Canis
familiaris). APPLIED ANIMAL BEHAVIOUR SCIENCE
79 (2): 133-155
Weiss A, King JE, Figueredo AJ 2000 The heritability of personality factors in chimpanzees (Pan troglodytes) BEHAV GENET 30 (3): 213-221
Wilsson E, Sundgren PE 1997 The use of a behaviour test for selection of dogs for service and breeding .2. Heritability for tested parameters and effect of selection based on service dog characteristics. APPLIED ANIMAL BEHAVIOUR SCIENCE 54 (2-3): 235-241
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