Social grooming is a behaviour in which social animals, including humans, clean or maintain each other's body or appearance. The grooming is present throughout the animal kingdom, from bees to humans. The grooming that occurs between two individuals of the same species is called conspecific grooming or allogrooming.
It can be found in horses, for example. "Put several horses together in the meadow, and very quickly you can observe two of them in a strange position, head to toe, scratching each other at the withers, or then near the croup, the base of the tail or simply along the back. It is above all a social act, practised between horses who appreciate each other or who maintain harmonious relations. The grooming is thus a method of choice to establish a hierarchical bond, but it also has an essential soothing function." Émilie Gillet
"Practised by many primates, delousing (social grooming) helps to strengthen the bonds between the members of the group. Delousing relationships can take place between a mother and her child, or between adult monkeys. Living in group is sometimes harsh, and many monkeys use their delousing services as money to obtain favours or to gain access to things that can improve their esteem. Grooming relieves the tensions created by competition. Too much stress reduces female fertility: stress hormones block the action of reproductive hormones such as oestrogens and progesterone (ovaries no longer release eggs and pregnancy can be compromised). Delousing provides a balance; it stimulates the production of opium-like substances that annihilate the effects of stress hormones."
We have all heard of this psychologist from the United States, Harry Harlow, whose experiments with young macaques in 1958, although controversial, showed the importance of care, conspecific physical contact and accompaniment in cognitive development. Those who were deprived of them refused to eat and went into a state of emotional shock. When they were offered an adoptive mother, they preferred the furry mother, who had no milk, to the iron wire mother who had water and milk. So that's the importance of the feeling of softness and comfort! Let's think about it next time the little one misplaces his security blanket…
For us humans, touching the other can quickly take on different connotations from the intention we had at the beginning. For example, it is not socially permitted to hug your boss or gently pet your banker's back. In some societies, it is very frowned upon to only get a little too close to the other, or worse: to touch him. However, the need to be touched is no less great in humans; the caress, which is granted profusely to our dear pets, appears as a flagrant lack in so many of our fellow creatures. Humans have therefore adapted conspecific touch to make it socially acceptable: hair salons, beauty salons, spas and massage, body care centres have always been the latest chic in all societies for thousands of years. And then, of course, part of manual therapy, when it is pleasant, is also a form of social grooming.
Houlala! I can already hear the reaction: "Social grooming manual therapy??? Not possible !! What is she saying???" Well, yes, it is! This is social grooming and social grooming is GOOD and NECESSARY to health.
A team of Swedish researchers presented a comprehensive book in 2016 on all aspects of the C-Tactile afferent fibres, those that "carry" this pleasant, emotional touch message from the periphery to the central nervous system: Affective Touch and the Neurophysiology of CT Afferents, Hagar Olausson, Johan Wessberg, India Morrison, Francis McGlone, Editors. We will develop the subject in other articles. However, this fibre, the C-Tactile afferent fibre, was first described in 1939 in furry animals, and it took 50 years for it to be described in humans. It's a C-type fibre, so it's Group IV. This is also important because Group IV fibres tend to travel up to the parabrachial area of the brainstem and activate homoeostasis regulation centres. This makes sense, if we go back only 4 paragraphs where we learn that the told that social grooming stimulates substances that inhibit stress hormones...