James Rilling is a Professor in the Department of Psychology and the Department of Psychiatry and Behavioral Sciences at Emory University. He is also the Director of the Laboratory for Darwinian Neuroscience.
What’s the big idea?
A neuroscientist, who is a father himself, explains the evolution of human fatherhood: from the divergence of our species from the great apes to our modern world of changing paternal expectations. Father Nature is the story of what men can expect when they’re expecting.
Below, James shares five key insights from his new book, Father Nature: The Science of Paternal Potential. Listen to the audio version—read by James himself—in the Next Big Idea App.
1. Among our closest primate relatives, human males are unique in their degree of involvement in raising their offspring.
Xiao Qiang was born in southwest China’s Sichuan province with twisted arms and legs and a hunched back that prevented him from walking. At age three, his parents separated, and his father, Yu Xukang, decided to raise him alone. The only school that would accept his son and accommodate his handicap was nearly five miles away and inaccessible by public transportation. But Xukang was determined for his son to have an education. He would wake up at 5:00 a.m. to prepare Qiang’s lunch and then carry him on his back to school. He would then walk back home to go to work to earn the money needed to provide for the two of them, only to retrieve his son from school later and carry him home again. In all, he traveled almost 20 miles each day to provide Qiang with an education.
Now contrast this devoted human father with chimpanzee fathers. Adult males aggressively compete for dominance and the opportunity to mate with as many females as possible. They make war with neighboring chimp communities and rarely care for their young. In fact, they occasionally kill infants sired by other males.
In about 95 percent of mammals, including most primates, adult males do not provide any significant parental care. Instead, care is provided by the mother, and males use their energy to pursue mating opportunities. This is also true among our closest relatives among the primates, chimpanzees, and bonobos. Therefore, we think that our capacity for paternal caregiving evolved during human evolution.
No one knows for sure why this happened, but I suspect these were important factors. First, there was a need. In species where males do provide care, it is usually because the offspring will not survive with maternal care alone. When chimpanzee offspring are weaned by their mother, they can already forage for themselves and provide all the calories they need to survive. Partly because of the energetic requirements of our massive brains, human children are not self-sufficient after weaning and continue to need provisioning. Human fathers often help with this provisioning. It’s a major commitment since those children typically don’t produce as many calories as they consume until about age 20.
“In about 95 percent of mammals, including most primates, adult males do not provide any significant parental care.”
Another important ingredient for paternal care is paternity certainty. Across the animal kingdom, males are more likely to provide parental care when their probability of paternity is high—when it is likely they are the father. There are indications that at some point in human evolution, our species became more monogamous, which helped provide males with paternity certainty.
Beyond provisioning, fathers have the potential to carry, hold, feed, clean, nurture, and play with their children, and do so in many human societies. Fathers often seem to be part of a team of allomothers that help the mother with direct infant and child caregiving. The result of all this provisioning and allomaternal support is that human mothers can wean their infants much earlier than great ape mothers, which shortens maternal interbirth intervals and increases human fertility. Part of our species’ success stems from having out-bred other primates.
2. Paternal care matters for child development.
Research shows that children with positively engaged fathers tend to have better developmental outcomes. Children do best when their fathers are warm, nurturing, sensitive, and responsive, and if they set and enforce appropriate limits. Children with such fathers tend to have better mental health, fewer behavioral problems, do better in school, and have more friends. That doesn’t mean that a child cannot do well without an engaged father, only that the odds improve. It is probably no coincidence that most of this research has been done in modern, Western societies where many couples live as isolated nuclear families apart from their relatives, resulting in fathers often becoming the most available and most important helper.
But how and why does paternal involvement help children? For starters, good fathers seem to help children learn how to regulate negative emotions. This may be through modeling the behavior, explicit teaching, or rough-and-tumble play, which has myriad benefits for children’s psychosocial development. Many fathers also gravitate toward the role of what the developmental psychologist Daniel Paquette has labeled activating their children. That is, they tend to supervise and encourage their children’s exploration of the world outside the home. They help teach children that the novelty, unpredictability, and competition they encounter are not to be feared but embraced as an opportunity for growth and success. Mothers and other caregivers can also activate children and help them learn to regulate emotions. It’s just that fathers are often drawn to these roles.
3. Male physiology was modified during human evolution to endow paternal potential.
A lot of men like the idea of having high testosterone, but it is a double-edged sword. Testosterone can motivate the pursuit of mates and social status and support certain aspects of paternal caregiving when it requires intense aerobic or muscular exercise. However, it interferes with the sensitive and nurturing care of infants, and it siphons energy from maintenance, suppressing the immune system and accelerating aging. So, it makes sense that men experience a decline in testosterone when they become involved fathers.
Among fathers with infants, those with lower testosterone pay more attention to their infants, affectionately touch them more often, and are more involved with their instrumental care. Despite these lower baseline levels, testosterone spikes in response to infant crying, which may be a mechanism to prepare them to defend their infant if needed. There is also emerging evidence that new fathers experience increases in another hormone, oxytocin.
“Among fathers with infants, those with lower testosterone pay more attention to their infants.”
We think of oxytocin as a maternal hormone, but it also plays an important role in father-infant bonding. While mothers with higher oxytocin levels tend to be more affectionate with their infants, fathers with high oxytocin levels tend to physically stimulate their infants more. If you give fathers of infants or young children extra oxytocin, through intranasal administration, they touch their infants more and play with them in a sensitive and challenging manner. Oxytocin appears to be doing double-duty, since the same oxytocin that helps them bond with their infant also helps them bond with their partner. In fact, intranasal oxytocin has been shown to increase men’s attraction to their partner, improve verbal and nonverbal communication with their partner, and perhaps even decrease their interest in extra-pair mates.
The neural circuity involved in paternal behavior appears similar to that responsible for maternal behavior. This includes an ancient subcortical motivational system that relies on dopamine and helps us to find our offspring rewarding and to want to take care of them. There is also a series of cortical systems involved in empathy that help us understand our offspring’s emotions, intentions, thoughts, and needs. Finally, our prefrontal cortex helps keep our negative emotions, such as frustration and anxiety, in check so that we can be better parents. In animal models, new fathers experience neurobiological changes that tune their brains for parental behavior. Neurobiological changes in new human fathers are also being described now for the first time.
4. Paternal behavior is highly variable.
An array of factors influence paternal behavior, including developmental influences from when fathers were boys, such as paternal role models and the safety of their environment; current familial influences, such as maternal employment, maternal encouragement of paternal involvement, paternity certainty, and the availability of other allomothers; social-structural influences such as population sex ratios, the availability of paid paternity leave, and prison reform; and finally, sociopolitical and cultural influences.
“The qualities of the ideal, traditional father are remarkably consistent across nations.”
Among modern nation-states, the qualities of the ideal, traditional father are remarkably consistent across nations. Rather than warm and nurturing, traditional fathers in many nations were expected to be stern, authoritarian, and emotionally distant providers. However, another highly consistent trend across nations is that modern fathers are moving away from this traditional ideal toward one characterized by greater warmth and involvement. Overall, the research suggests that strategies to increase positive paternal involvement should include efforts to make neighborhoods safer, provide men with more job opportunities, paid paternal leave, reduced prison sentences for non-violent victimless crimes, and educating young people about the importance of positive paternal involvement.
5. Both children and fathers benefit from positive paternal engagement.
Having children is associated with increased longevity and slower brain and cognitive aging. In interviews I conducted with fathers from the Atlanta area, they mentioned several rewards of fatherhood. Many fathers enjoy teaching their children skills and values, and imparting knowledge to them. Many also enjoy witnessing the miracle of child development: how a single-celled zygote can ultimately develop into a human being who can walk, talk, think, and love.
Fathers also derive many important subjective rewards. These include feeling loved, seeing the world through their child’s eyes, vicariously experiencing their joy, seeing their child as an extension of themselves, and even as a chance to start over in life and correct mistakes they had made in their own. Many fathers told me how therapeutic it was to have someone listen to them about their experience as a father. A few men even cried, and those are the interviews that I remember best. The common theme was that becoming a father added great meaning and purpose to their lives.
To listen to the audio version read by author James Rilling, download the Next Big Idea App today:
