One can easily imagine how, in some contexts, the progenitors of domestic dogs were best served by boldness (being the first to venture near a human settlement) or by caution and timidity (letting a littermate be the one to go play with that big, fuzzy animal that humans call lions). What is not clear yet is how much of a dog’s physical appearance is linked to behavioral tendencies. Holly looks more like a Border Collie than does her sister Kit and, in general, we know that shyness is relatively common in many of the herding breeds. Could there be a link between looks and personality?
There has been shockingly little research on the links between physical appearance and behavioral tendencies, but Swedish ethologist Kenth Svartberg did some interesting work on personality in dogs while at Stockholm University. One of his studies found “large behavioral differences between breeds in the traits [of] playfulness, curiosity/fearlessness [similar to the “shy/bold” continuum mentioned earlier], sociability and aggressiveness.” Clearly, there appear to be strong genetic links between looks and behavior. Does that mean that more of Holly’s genes relate to the Border Collie in her? Could be. Of course, we’ll never know, but it is certainly possible and biologically logical to predict links between a dog’s appearance and her personality, even within a litter.
Starter Houses. Beyond an understanding of the role of genetics, research is increasingly focused on the effect of in-utero experiences on the development and, ultimately, the health and behavior of an individual. Until recently, our developmental considerations have focused on the influence of genetics and the environment during “early development”—the old nature/nurture argument, as it were. The period we defined as “early development” began at birth and followed an animal through infancy, childhood, adolescence and adulthood. However, new information has alerted us to the important influence of in-utero experiences, an environment we’ve never before considered as having an affect on an adult animal. Much of the research I’ll mention here was done on humans, but there is no biological reason to not generalize it to canids.
In general, the influence of a mother’s experience on her fetus is profound: her sleep pattern teaches the developing child about the cycle of day and night. Her food preferences influence her baby’s after birth. If the mother is seriously deprived of food, her infant will be predisposed to diabetes and high cholesterol as an adult. Most relevant to a fearful puppy, a mother suffering from extreme anxiety puts her offspring at high risk of being anxious and fearful, even as an adult. Apparently, high levels of the stress hormone cortisol produced by the mother result in fewer cortisol receptor cells in the pup (or child or monkey, etc.). This low number of receptor cells means that the pup’s brain is unable to perceive and respond to high levels of cortisol in his own body until the system is overloaded with it. Then the brain goes on red alert, sending the emotions into full panic mode, even in situations that would be only mildly stressful for an average individual.
In addition to the significant influence of a mother’s influence on her young, we also know now that the experience of each individual within the uterus is different. Minor differences in nutrients, for example, have long been known to be a factor in major differences in the size and health of animals within a litter. Even genetic clones—identical twins for example—aren’t behaviorally identical. Though they may look alike, they usually have remarkably different personalities. Since they developed with the same set of genes, only in-utero experiences can account for their behavioral differences. Developmental psychologists are learning that for twins, development in the womb is a kind of dance between the two that, by the time they are born, has shaped their personalities.