Biology and Paternal Care
by Jack Kittredge
Somewhere over 95% of earth’s mammal species rely almost exclusively on the mother to nurture and raise the young. A good number of studies have been done on the biological basis of this nurture. Most animal behavior is mediated by chemicals in the brain and maternal care is located in a brain region called the mPOA (medial preoptic area) of the hypothalamus, which undergoes dynamic hormonal and epigenetic remodeling during pregnancy.
Very little research has focused on paternal care by males, however, either ‘sexually naïve’ ones without breeding experience or ‘sexually experienced’ ones, whether interacting with their own biological offspring or as ‘alloparents’ (think uncle) dealing with another male’s offspring. When witnessed, male paternal activity can range from care and attention to violence and even cannibalism.
A team of researchers from Princeton decided to investigate this field and have published in Nature a study of cues which regulate paternal behavior. They chose African striped mice as the subjects, a variety of rodent that has been observed exhibiting diverse behavior from grooming to attacking their young.
They placed various male mice with striped mouse pups. Not surprisingly, as with the mothers, this precipitated neural activity in the male’s mPOA. Heightened activity corresponded to periods when the mouse was exhibiting helpfulness; when lower, hostility. This response had nothing to do with the past sexual experience of the subject: ‘naïve’ as well as ‘allo’ mice showed the same reaction as biological fathers.
Encouraged that the study found a correlation between brain activity and behavior, the team went further and looked at the changes in behavior and their connection to brain biochemistry. The more caring mice showed lower levels of a gene called Agouti, which is traditionally associated primarily with metabolism and skin pigmentation. The study showed that solitary males possessed a lower level of Agouti, compared to those who lived in groups.
To determine causation: whether a high Agouti level was the driver of hostility, or if the emotion somehow increased the gene’s prevalence, the team artificially boosted Agouti through gene therapy. Previously nurturing mice became less interested in the pups or even volatile regarding them. Later, mice relocated from communal to solitary living conditions experienced lower Agouti levels and became more interested in the pups again.
What can we make of all this? The team of course properly calls for more research and discourages early conclusions. But what appears possible, at least in mice, is that fathers, who Nature does not always grant a positive attitude toward caring for their offspring, can be moved in that direction by biological means.
Whether this flows from less stressful living conditions, better nutrition, or other environmental conditions, perhaps human behavior can occasionally be improved by altering the way we live.
All of us know people who had an absent or abusive father and who are suffering thereby. If we could prevent even a small portion of that, and replace it with a natural level of caring, how much pain on both sides could be removed?
