Oh Great Baby Poo-bah! by Mikki Miranda

I love children - neonates and babies, in particular. As a way to comfort myself during my Mum's cancer battle a decade ago, my sister and I would usually visit the hospital's nursery and look at the newborns. Babies signify a new life and a new opportunity to see the world in another way. Indeed, they are helpless creatures who need someone to take care of them and lead them until they are finally ready to become independent. Holding these ideas and experiences, I know I am looking forward to two goals in the future: (1) to become a neonatologist, and (2) to become a mother. I am quite reluctant of the second one because of a few particular, and some rather shallow, things; aside from giving birth, I am scared of babies' poo and changing dirty diapers. 

Thanfukfully, researchers from Macquarie University in Sidney and University of Washington in Seattle studied disgust in terms of how mothers' react to the smell of poo of their own infants and to other peoples'. Disgust, as the researchers said, is a powerful behavioral adaptation that can act as a signalling force against pathogenic and infectious agents. Although disgust may serve as a behavioral guard against diseases, it is true that there are many circumstances in which disgust may come as a disadvantage. One of them is that a mother's disgust towards her baby's poo can pose a risk by obstructing her ability to care for her baby. (Case, Repacholi & Stevenson, 2006)

Their research consisted of two studies. In their first study, they administered a "Baby smell questionnaire" to 42 mothers of infants. The participants rated their reactions (with a 7-point scale) to questions relating to the last time they changed their baby's diaper. The responses ranged from "didn't feel sick" to "felt very disgusted" to "found the smell intolerable". Furthermore, the participants rated their reactions to the last time they changes the feces-soiled diaper of someone else's baby using the same scale. As the researchers predicted, the mothers rated the smell of their own baby's feces-soiled diapers less disgusting than those of someone else's.

Actually I have a greater aversion to adult diapers.

Their second study is basically a practical application of the first. The researchers presented mothers with actual feces-soiled diapers and they hypothesized that a bias would emerge even when mothers are blindly presented with the odor of their own baby's diaper and the diaper of another baby insofar as the mothers would label the former as less disgusting as the latter. With 13 mothers participating in the "Baby smell study", the experimental results supported the researchers' hypotheses. Even when the mothers were blind to the source of the diaper and social desirability was controlled, the mothers found the smell of their own baby's feces-soiled diaper as less disgusting compared to someone else's.

One possibility for this is the factor of repeated exposure which may subsequently result in selective habituation to a specific odor quality. Another possibility, the researchers claim, may not be because of exposure but rather a "detection of some quality that signals relatedness". Putting it in an evolutionary perspective, the idea that there are specific odors that signal kinship (even if they are disgusting) is a plausible way in maintaining genetic survival. 

It's such a comfort to know that changing dirty diapers is not as smelly as it seems, as long as it came from one's own. As a future doctor, I'm pretty reluctant to handle fecal material coming from children, or generally people, that I do not even know. All for the sake of science and goodwill, I guess I do have to face them with courage and dignity.

Yes.

Reference:
Case, T., Repacholi, B. & Stevenson, R. (2006). My baby doesn't smell as bad as yours: The plasticity of disgust. Evolution and Human Behavior, 27(5),357-365.