Parents aren’t easily disgusted, but only once their child has started eating solids. The level of disgust that parents experience seems to change over time, which could have evolved to both protect their child and prime their immune system.
Disgust probably evolved as a way to avoid pathogens, such as those in faeces or vomit, as a sort of “behavioural immune system”, says at the Laureate Institute for Brain Research in Tulsa, Oklahoma, who wasn’t involved in the new research.
at the University of Bristol, UK, was therefore curious about how parents tolerate dirty diapers, or nappies, having recently become a father himself. “That’s obviously an ideal kind of natural experiment, where you’re faced with a lot of disgusting nappies,” he says. “What does that do to your disgust habituation?”
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To learn more, he and his colleagues recruited 99 parents and 50 non-parents, aged from 18 to 73, in the US and the UK. Nearly half of the parents had nappy-wearing babies, of whom most changed at least two nappies a day.
The participants completed a standardised – which asked them to rank their reactions to things like seeing a cockroach or touching a dead cat – as well as parenting-related questions, like changing nappies close to dinner.
Next, the researchers tested the participants’ disgust behaviour by measuring how long they looked at a repulsive image – such as vomit or soiled nappies – versus a more neutral image, like a sleeping dog or bowl of fruit.
The researchers found that the parents of babies who had already been weaned were less easily disgusted than non-parents and parents whose babies were still exclusively consuming milk. “It looks like the constant barrage of bodily effluvia that emanates from their children just presents them with such a disgust experience that seems to be associated with reduced disgust avoidance across the board,” says Dalmaijer.
But the parents of not-yet-weaned babies were slightly more easily disgusted than non-parents. This could be an unwitting way to protect younger babies from germs, says Dalmaijer.
The later acceptance of disgusting substances post-weaning might allow for a slight drop in parents’ protective barriers, which could help to prime their children’s immune systems, he says.
“These are fascinating findings shedding light on how disgust helps us face life’s challenges,” says Berg. “They suggest that this [disgust] system can self-modulate in an impressively nuanced way to meet the demands of parenting: doing the often dirty business of raising an infant, while also keeping yourself and your child safe, and helping your child develop their own strong immune system.”
PsyArXiv
