Suzana Herculano-Houzel

The advantages of licking your young


Everyone knows that receiving affection feels good. But in recent years, neuroscience has discovered why: the brain has a specialized system for detecting caresses – touches that glide gently over the skin – and reporting their occurrence both to regions that take care of the body’s sense of well-being, and to others that then inhibit various stress responses.

Of course, a system of sensitivity to affection has its attractions for adults, but it is in newborn babies that its importance becomes most evident: it works like a powerful mother-detector. After nine months in the comfort of the womb, with a home, food and warmth, frequent cuddling is the best indication that someone is around to feed, warm and protect the baby – and that someone is usually the mother.

Not receiving affection, therefore, is a sign of not having a mother around – and the lack of activation of the mother-detectors sets off the alarm with a generalized stress response. With the stress hormones, the body and brain go out of “development” mode, into “survival” mode, storing reserves, and only come out of it when the brain detects affection that indicates that someone has started to take care of the baby. That’s why premature babies left alone in incubators, with medical care, food, oxygen and warmth but separated from their mothers, don’t grow, have various health problems and take a long time to be discharged. Fortunately, it’s nothing that affection can’t solve.

But the benefits of affection go beyond allowing the baby to develop peacefully. A group from McGill University in Canada has been showing for the last ten years that rats that are properly licked by their mothers during the first week of life become calmer and less anxious adults than rats raised by unaffectionate mothers; they have healthier hormonal and behavioral responses to stress; and they in turn become affectionate mothers to their own offspring. Experiments with adoptive mother rats have shown that the determinant is the behavior of the mother, biological or not: affection begets affection.

It’s a highly desirable vicious circle, where affection is self-propagating. Be treated well and cuddled in childhood and, as well as enjoying all the benefits of a healthier response to stress as an adult, you’ll cuddle your children too, offering them the same benefits. Cuddle your children, therefore, and you’ll already be taking care of your grandchildren’s well-being!

Originally published on Folha de São Paulo on June 16th, 2006. 

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