Paternal care, paternal brain

I grew up in a family with traditional gender roles which emphasize a clear-cut division of labor between men and women. When I complained to my father that he was not spending enough time with me, he would always argue that my mother was my caretaker and nurturer, whereas his responsibility lied in providing financial means to the family. “People ought to do what they do the best” is what my father used to say. By saying that, he didn’t mean that he, as an individual, happened to have a knack for business while my mother happened to be loving and good with kids; he said that because he felt that men were not hardwired for child rearing.

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Traditional gender roles. Source: WhaleOil

As a society, the importance of paternal care had been somewhat neglected, and “the family guy” had been a rare occurrence. But things are changing. In an article from Scientific American written in 2012, the author, Emily Athens, noted that, in the U.S., there were three times more stay-at-home fathers than there were a decade ago. And according to a developmental psychologist studying American fathers and mothers starting from the 1970s, men had changed from “never bathed their children” to “would feel embarrassed to say they hadn’t changed their children”. The growing trend of men-women exchange on the work-home front is being justified by research evidence that reveals its inevitability.

First and foremost, there is evidence that men are as good as mothers at recognizing the cries of their baby (Gustafsson, Levréro, Reby, & Mathevon, 2013). The popular belief that women’s “maternal instinct” dictates that they should be better at this task turned out to be unfounded. Previous studies that claimed to have confirmed the “maternal instinct”

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Source: Parents Magazine

theory didn’t take into account that mothers spend an awful lot more time around their babies than fathers do in this society where women are still predominantly the primary caretaker. In this study, where “time” was factored in, researchers found that fathers were equally accurate as mothers at recognizing their baby’s cries. The ability to recognize baby’s cries is, therefore, not rooted in our genetic make-up but rather in experience. In other words, there is no innate predisposition for either gender to be more sensitive to the “distress call” of newborns; new parents pick up this skill by being exposed to their babies, tending to their needs, learning and memorizing their cries.

Speaking of learning and memory, now would be a good time to zoom in and look at what parenthood does to fathers’ brains. A little bit of background information first: being able to recognize own kin versus the others would greatly increase reproductive success and offspring survival (because if you cannot recognize your offspring, it would be hard to provide for them, and consequently, it would be hard to make sure that the genes you passed on would flourish and thrive, so to speak). Kinship recognition in rodents has been proposed to work by olfactory neurons picking up the unique pheromonal odor of another rodent individual. Rodents are typically more responsive to their own pheromonal odor. They could recognize kin in this way because closer relatives would have more similarities in genes that code for those odor signatures (Sapolsky, 2017).

Using a mouse model, two researchers found that the physical interaction between a father and newborn offspring stimulated neurogenesis in the father’s olfactory bulb and dentate gyrus; no neurogenesis was observed, however, if the physical interaction was

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Source: Squeaks and Nibbles

inhibited by a mesh barrier (Mak & Weiss, 2010). This again suggests the importance of experience and of being involved in pup upbringing to developing a “father brain”, which means, in this case, enhanced olfactory memory and higher sensitivity to pheromonal odors. It also demonstrates that “father brain” is as real as “mommy brain”— parenthood does elicit neurobiological adaptive responses on the father’s part in face of a newborn.

To drive home the point that actual experience of caretaking is crucial to developing a parental brain that is independent of biological gender, I share with you an fMRI

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Comparing percent signal change in amygdala and STS in PC-fathers, PC-mothers and SC-fathers upon viewing infant-related stimuli. Source: Abraham et al., 2014

neuroimaging study that examined brain activation pattern of heterosexual fathers, homosexual fathers and heterosexual mothers upon viewing infant-related cues. Homosexual fathers and heterosexual mothers are both primary caretakers (PC), in that they spend more time with their kids and are more intimately related to the child-rearing experience compared to heterosexual fathers, who are secondary caretakers (SC). And what did the researchers find? Lo and behold, when viewing the videotape of them playing with their babies, PC fathers had amygdala activation resembling that of PC mothers, and at the same time, had superior temporal sulcus (STS) activation comparable to that of SC fathers (Abraham et al., 2014). The researchers interpreted these results as reflecting the malleability of paternal brains, by which an alternative pathway of adapting to parental roles (i.e. co-activation of STS and the amygdala) could be provided by experience in care taking, compensating for the absence of the evolutionarily ancient “maternal care” pathway that is triggered by pregnancy, birth and lactation.

In all, experience is key. Child rearing and care taking are not functions unique to females. There is a whole set of adaptive changes in the male brain, ready on call, that could help men to assume the role of a father in a more engaged way, but only if the father spends time with his own child. I hope men are not held back by the popular but problematic belief that they are doomed to be clumsy and less attentive to their babies because they don’t have “maternal instincts”, and similarly, women should not be expected to take all responsibilities of child rearing because they are supposedly “born to be good at it”.

References

Abraham, E., Hendler, T., Shapira-Lichter, I., Kanat-Maymon, Y., Zagoory-Sharon, O., & Feldman, R. (2014). Father’s brain is sensitive to childcare experiences. Proceedings of the National Academy of Sciences, 111(27), 9792 LP-9797. https://doi.org/10.1073/pnas.1402569111

Athens, A. (2012). Family guy. Scientific American. Retrieved from https://www.scientificamerican.com/article/family-guy-2012-10-23/

Gustafsson, E., Levréro, F., Reby, D., & Mathevon, N. (2013). Fathers are just as good as mothers at recognizing the cries of their baby. Nature Communications, 4, 1698. Retrieved from https://doi.org/10.1038/ncomms2713

Mak, G. K., & Weiss, S. (2010). Paternal recognition of adult offspring mediated by newly generated CNS neurons. Nature Neuroscience, 13, 753. Retrieved from https://doi.org/10.1038/nn.2550

Sapolsky, R. M. (2017). Behave: The biology of humans at our best and worst.

Featured image source: thevince, http://www.flickr.com/photos/the_vince/3539324228/

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