Earlier this month, Hopi Hoekstra gave a seminar on the genetics of behavior, a field she is expanding with her research on burrowing patterns in deer mice. In her talk, Hoekstra suggested that behaviors are heritable and, in the case of burrowing patterns, dependent on only a few key genes. Her research is considered revolutionary by many as it may help illuminate mysteries surrounding the origin of behaviors, and even personalities. The idea that certain behaviors could be linked to a few key genes has got me thinking about what these genes are and whether the inheritance of behavior is all that different from the inheritance of any trait. Are the genes actually coding for “behavior” or is the behavior an artifact of an inherited morphology or other trait?
Hoekstra suggested genes for dopamine receptors as being potential candidate genes that affect the burrowing behaviors she observed. But could there be morphological differences such as leg length, or musculature which also may contribute to a mouse’s burrowing ability? Could those few genes that appear highly correlated with burrow length actually be coding for physical traits which would then give rise to behavioral “artifacts?” This leads to the question of what is behavior and whether it is distinct from the physical traits we possess. I hesitate to agree with the idea that there are “behavior genes.” Rather, I wonder if we are confusing certain traits that are heritable with the behaviors that they may give rise to.
In 1958, Erwin Schrodinger wrote a book called Mind and Matter, which discusses the role that human consciousness plays in evolution (I put it on the list of “life-changing” reads). One topic he addresses, of particular interest in light of listening to Hoekstra’s talk, is the “genetic fixation of habits and skills.” Schrodinger’s perspective from half-a-century ago is not all that different from what we are potentially finding today in the field of behavioral genetics: behavior is heritable. But Schrodinger says something more: behavior and physique cannot be separated. “You simply cannot possess clever hands without using them for obtaining your aims … You cannot have efficient wings without attempting to fly. You cannot have a modulated organ of speech without trying to imitate the noises you hear around you. To distinguish between the possession of an organ and the urge to use it …. would be an artificial distinction,” (p.121). Is behavioral genetics making a field out of this “artificial distinction?” In our own lives we could think of the behaviors we have and ask whether these behaviors are more likely to be a consequence of “behavior genes” or genes for traits that make us more likely to have certain behaviors. I enjoy running. Did I inherit a “running enjoyment” gene or is it more likely that I inherited genes for a certain leg-type? or certain endorphin-craving brain receptors?
Because most things make more sense with analogies (at least to me), I like to think of it this way: Let’s say we have a ball of play-do. It is spherical, smooth and malleable as a consequence of its structural makeup. We place the ball of play-do on an incline slope and it rolls. Is the rolling behavior independent of being round? Would we still see rolling behavior in a flat or frictious environment? Probably not. In my opinion, the quest for “behavior genes” is not different than the same quest we’ve been on for the last century: understanding the distinction and interplay between all genes, their expression and the influence of environment.