Maternal Behavior in Virgin Mice: Mommy Brains, Mommy Rats, and Monkey Business

So babysitting can make you maternal. Maybe give you "mommy brain."

But before you get the idea we can we turn women with nary a maternal instinct into full-fledged breast-feeding, Baby Bjorn-wearing, brownie-baking super nurturers, let's back track.

What we got is a new rat study out of Tufts University published in Brain Research Bulletin. What, you've let your subscription lapse? No worry, seems virgin rats who hung out with newborns started caring for the rat pups, acting all motherly, most of them anyway. Researchers also noticed the "moms" developed new neurons that migrated to their olfactory nerves. In other words, the rats turned into mothers by virtue of being with needy babies, possibly due to a better sense of smell allowing them to recognize and bond with their adopted broods.

One of the researchers offered another explanation to ScienceDaily. Something, possibly the hormone prolactin, might have produced both the maternal behavior and the increased olfactory nerves. So starting to care for the young might stimulate prolactin production and lead to new behavior and brain cells.

Obviously the exact relationship between the increased maternal behavior and the brain could use some fine tuning.

But that didn't stop some folks from jumping to conclusions about human moms and wanna-be moms.

Elizabeth Richards over at Slate's suggested women should seek out a small kid to get those maternal urges brewing (Taking Care of Babies May Change Your Brain):
For women who are bent on procreating but need a neuronal nudge, the rat study (if it proves to be an accurate model for humans) implies that hanging out with your niece or nephew might help provide it. Scientists have long observed that exposing many species of animals to youngsters generates nurturing impulses. (That also applies for cute cross-species photos of dogs taking care of ducklings). Think of it as an internship in mothering. Among some primates, young females are often eager to babysit infants in order to learn how to take care of them, explains Sarah Blaffer Hrdy, professor emeritus of anthropology at the University of California-Davis, who has studied the practice among the langur monkeys in India. This readiness to bond with nonbiological offspring explains why human adoption works so well.
Last I checked, my female friends were so like rodents and langur monkeys. Especially when it comes to complex behaviors like parenting. The last languar I met was so overprotective, a real helicopter parent, reminded me of my sister-in-law. After her maternity leave ended, the conflicted monkey momma struggled with going back to work. She wanted another baby, but her mate wasn't so sure. I mean, they lived in a small tree and didn't have many fruits and nuts.

Now I love a good rat study as much as anyone who's taken experimental psychology and had to snooze through all those maze studies from the 1950's. But, honestly, it's hard to attribute on-going maternal behavior, the staying up all night, the wiping of snotty noses, shopping for new school shoes, etc. to neurons in women's olfactory nerves. I don't discount smell plays a large role in our lives, I took that course too. It's just there's so much involved in tending to babies and the sense of smell is but one factor. Trust me, I have like zero sense of smell and I do all that stuff with love in my heart if not always a smile.

Let's face it, extrapolating the rat study to humans takes some effort. Maybe the act of caring for small children instills some confidence in our nurturing skills. Not hard to believe it could nudge the mothering instinct and baby plans along. Or maybe babysitting is simply practice that hones the soothing and wiping skills. We just get better at it.

I'm still having trouble with the women who want to be mothers and want to improve their maternal instincts (emotion). The rat study tells us nothing about these women, only that possibly, being with babies might produce more mothering behavior, not emotion per se. We don't know if the new "momma" rats feel more maternal. We certainly don't know if they're longing for more babies and getting a fuzzy feeling inside.  No one asked them. The research team observed their behavior. We've no idea if simply being with young children and babies makes people, women, feel more warmth, more protective, more responsible, more love, that is, more maternal.  Nor if it makes them wanna get knocked up or actually gets them knocked up. At least, this study cannot tell us this. 

So to the women who want that "neural nudge" (I guess to feel warm and gushy inside at the prospect of cuddling a newborn?) - my advice, don't rush out to the nearest playground on the basis of this data. 

Much love to the rats and their researchers, but maybe we should work out some of the details before we start attributing maternal bonding and behavior to our noses and rent out our kids to kinfolk who kinda- sorta-wanna procreate. 

FYI: Except for the occasional birthday party invitation I don't turn down, my kids are available most evenings and weekends.

DOI: doi:10.1016/j.brainresbull.2009.08.011

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