What makes massage feel so nice, physiologically?
Research Scientists have been massaging mice with little paintbrushes to find out...
It was already understood that massage affects the body's CT afferent neurons ("pleasant-touch nerves") which switch on the 'feel good' factor and switch off anxiety. What this batch of research pinpointed was the specific genetic marker for that response & then linked it behaviorally back to evolutionary selective advantage in animals who socially-groom with the effect of calming the group.
Meaning, that animals (like mice) which tend to live in social groups had better chances of survival if they enjoyed engaging in social grooming which has the effect of calming everyone in the group down, keeping them together and thus providing protection and the potential for passing that same genetic marker on to their offspring.
Massage undoubtedly makes most people feel more relaxed and less anxious, and therefore overall probably more sociable. The fact that this response is down to a single evolutionary genetic marker in our DNA, one that we probably share with most mammals, is rather amazing, don't you think?
Source: The Scientist magazine, referencing work by The California Institute of Technology, 2013