0.10 Biology and personality  (Page 6/22)

…It appears that mothers who protect their high reactive infants from frustration and anxiety in the hope of effecting a benevolent outcome seem to exacerbate the infant’s uncertainty and produce the opposite effect. This result is in greater accord with the old-fashioned behavioristic view than with the modern emphasis on the infant’s need for a sensitive parent. (pg. 205; Kagan, 1994)

In support of Kagan’s studies, Fox and his colleagues have demonstrated a specific gene-environment interaction that predicts behavioral inhibition in children aged 14 and 84 months (young 1 year-olds and 7 year-olds; Fox et al., 2005). Although it is difficult to describe such studies in simple terms, suffice it to say that children with a combination of the short 5-HTT allele (a gene for the molecule that transports the neurotransmitter serotonin) and low social support are at an increased risk for behavioral inhibition. When the children were 1 year old, behavioral inhibition was measured in terms of the latency to approach novel objects and unfamiliar adults, and when the children were 7 years old it was measured in terms of their disconnection from a group of children at play. The short allele of the 5-HTT gene has been associated with increased anxiety, negative emotionality, and relatively strong coupling with the amygdala. Therefore, in the absence of social support, children with the short allele are more likely to experience stress in the presence of novelty and strangers (Fox et al., 2005). Moffitt, Caspi, and Rutter have written an excellent review of how psychologists and other scientists approach this important new field of gene-environment interactions, and in that review they suggest that it is most likely that such interactions are common in psychopathology (Moffitt et al., 2006).

Discussion Question: Jerome Kagan studied temperament, and found that approximately 10% of children are shy and inhibited and approximately 20 percent of children are curious and adventurous, and these temperaments are most likely to continue into adulthood. Consider the people you know. Have their basic temperaments remained constant throughout their lives? What about you?

Sociobiology and Evolutionary Influences on Behavior

Sociobiology is a relatively new field of study that applies evolutionary biology to social behavior (Barash, 1977; Wilson, 1975). Although much of the research underlying sociobiology has been conducted with non-human animals, the value of this research and its applications to understanding human behavior and personality should not be underestimated. Samuel Gosling and his colleagues have demonstrated that a wide variety of other animal species have personality traits similar to those of humans (Gosling, 2001; Gosling&John, 1999; Gosling, Kwan,&John, 2003; Gosling&Vazire, 2002; Jones&Gosling, 2005; Mehta&Gosling, 2006). When the ethologists Nikolaas Tinbergen, Konrad Lorenz, and Karl von Frisch shared the Nobel Prize in 1973 it was the first Nobel Prize awarded for the study of behavior. Sociobiology, a field similar to ethology, has offered valuable new perspectives on human behavior, perspectives on behaviors that do not always seem logical at first. As an aside, sociobiology also allows us to address an exciting variety of human behaviors, including the apparent evolutionary and neurobiological bases for laughter (see Panksepp, 2005).