Critters engage in considerable social grooming which has led scientists to wonder about and to investigate underlying mechanisms as well as the origin and evolution of these behaviors. The 31 January 2013 cover of the British journal Nature shows two monkeys on the beach of a river in Cambodia engaged in such behavior. The title of the cover is "At a Stroke."
Below you will find the citation of the accompanying article and the editor's summary plus a reference to the abstract which I urge you to take a look at. The abstract is abstract but we know it means something, but what? There are several barriers, e.g., the specialized language of the discipline, the audience for which it is aimed (scientists) and the experience (training, education, skills, experience) of the investigators.
I don't know how this happened but some "creatives" translated using critters I love from a wonderful site, "LOL Cats." I've included that connection at the bottom. It is beautifully done and is a good primer on doing science. If you watch it, watch all of it, right to the end.
Sophia Vrontou, Allan M. Wong, Kristofer K.Rau, H.Richard Koerber & David J. Anderson (2013) Genetic identification of C fibres that detect massage-like stroking of hairy skin in vivo. Nature 493:669–673
'Massage' neurons make it good to be stroked
Pleasant stimulation of skin serves important social functions in mammals, but has received less attention from molecular neurobiologists than the response to noxious stimuli. Now David Anderson and colleagues have used calcium imaging in live mice to show that a small population of sensory neurons in hairy skin — expressing the G-protein-coupled receptor MRGPRB4 — responds specifically to strokes from a small paintbrush intended to simulate natural stroking or grooming, but not to pinching or poking stimuli, which activate a different population of sensory neurons expressing MRGPRD. Pharmacological stimulation of MRGPRB4+neurons elicits positive reinforcing behavioural effects. The 'stroke-sensitive' neurons resemble C-tactile afferents, unmyelinated mechanoreceptive neurons found in hairy skin of humans and other mammals. The functional characterization of this novel population of neurons opens the way to identifying molecular transduction mechanisms and neural circuitry associated with a positive affective state — or pleasure.
Here is a video summary from Scientific American
The complete abstract may be read here: