What makes for good dads?

We have all experienced a mother’s unconditional love. What about our dads? Some of us have fathers who lend a helping hand in the kitchen, have polished our school shoes at night, made a cozy bed and put us to sleep. And then there are those in the opposite gang who leave everything for our mothers to do. Have we ever thought what makes dads good, more caring, and affectionate. And what could transform a ‘normal’ dad into one who kisses, hugs, and cuddles- just like mom!

Scientists at the HarvardUniversity, and Novartis Institutes for Biomedical Research, Cambridge, USA, seem to have an answer to these queries. With fascinating experiments in mice, they know what makes for good dads in these tiny creatures.

Young mice (called pups) depend on parental care to survive, just like humans. Mothers invariably take good care of pups while that from the fathers varies with species. Both sexes in some species of rodents like the Oldfield mice share parenting duties equally. In other related species like the Deer mouse, fathers contribute minimally to loving and raising pups.

Not just parenting habits, the two species also differ in their habitats. Oldfield mice are found in extreme harsh environments such as arid deserts and cloud forests. They live in small family-like groups, and seem to have adapted to their sparse environments by forming loving pair bonds, with both sexes sharing duties of parental care. The deer mice on the other hand, are widespread in their distribution and have a casual mating system.

Interestingly, both these species can interbreed and produce viable babies in the lab. This implies that scientists can use these animals to make a mixed family. Make babies that are half-oldfield and half-deer. It can also help them determine if the environment shapes a father’s behavior. 

The Deer mice (left) do not build nests, and fathers offer minimal care. Oldfield mice on the contrary (right) build nests, and both the mother and father take care of the young ones. Pups are seen in bright red color lying under the mother.

How do you know which mouse is a good dad? You can’t ask the pups, right? So how is that done?

Scientists do that quite fashionably. They give the breeding mice pair a home cage, lots of cotton to build a cozy resting place called nest, and observe their parental behavior.

 

They measure parental care by observing how fathers approach pups, move them with their front paws, lick them, huddle over them, and change their position to provide more comfort. This is done with the help of cameras that work day and night. The findings are published in Nature.

Scientists observe that Oldfield fathers offered care to the same extent as the mothers. The Deer mouse fathers did not take care of the pups.

Are these differences genetic? Or is it a result of how their dads loved them when they were kids? To address this doubt, scientists performed cross-fostering experiments. Oldfield pups were raised with deer fathers, and vice versa.

They found that the care a mouse received when he was a kid had nothing to do with the kind of dad he would become. This added weight to the possibility of a genetic link to being a good dad. But wait, what if oldfield pups need more care then deer pups? They demand it, so they get it. No, this isn’t the case either. Oldfield mice proved themselves to be awesome dads, irrespective of who the kid was- their own oldfield, or an adopted deer pup.

Hence, being a good dad is linked to genes. Scientists dug deeper into which genes make oldfield mice good dads? They found that the gene for vasopressin that controls nest-building behavior is expressed differently in these two groups of mice. Low vasopressin makes for good dads in mice!

With that information, can a not-so-loving deer dad be transformed into an awesome oldfield father? Yes. It can be done.

Inhibiting vasopressin neurons in the brain increased nest-building behavior in deer dads too! Alternatively, when high nest-building oldfield dads were given vasopressin injections in the brain, they stopped making nests, confirming that it was vasopressin that made them so different.

“Our genetic dissection of parenting opens new avenues of research for the understanding of a complex social behavior. Discovering how genes such as vasopressin may change specific aspects of behavior, will help understand how behaviors and the brain evolve”, signs off Hopi E. Hoekstra, Professor at the Howard Hughes Medical Institute, Harvard University, Cambridge, USA.

By Bhavya Khullar