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Maternal chemical signals help infants bond with strangers

A new study led by the Center of Developmental Neuroscience at Reichman University, Israel, has found that chemical signals in mothers’ body odor may have a significant role in supporting the development of infants’ social brains and make them capable of interacting with strangers from an early age.

While maternal body odors serve as important safety-promoting and social recognition signals, their role in human brain maturation has been largely unknown. A research team led by Yaara Endevelt-Shapira, a postdoctoral research associate at the Center for Developmental Neuroscience, has recently investigated in more detail the complex role of chemical signals in enhancing infant-adult brain-to-brain synchrony.

The scientists gave 62 mothers a cotton t-shirt each and asked them to use it as a pajama for two consecutive nights before the experiment. In a first stage of the empirical study, the mothers and their infants had electrodes placed on their heads and were seated initially back-to-back, then face-to-face. When they were facing each other, mothers and infants shown higher neural synchrony.

In a second stage of the experiment, 51 of the infants were seated face-to-face with a stranger – a woman with a similar age as their mothers who lived in a nearby area and had an infant of about the same age. While the infants interacted with this woman, they were exposed to either a clean t-shirt or the t-shirt that their mother used.

Infants who were exposed to a clean t-shirt showed a significantly lower inter-brain neural synchrony with the stranger than with their mother. By contrast, those exposed to the t-shirt with their mother’s body odor showed the same degree of neural synchrony with the stranger as with their mother. 

These findings suggest that scent preserves a chemical signal of the mother’s presence even in her absence, increasing the infants’ social capabilities and helping them survive in a constantly changing social environment.

“Human mothers use interbrain mechanisms to tune the infant’s social brain, and chemosignals may sustain the transfer of infant sociality from the mother-infant bond to life within social groups,” the authors concluded.

The study is published in the journal Science Advances.

By Andrei Ionescu, Staff Writer

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