Petting. Your dog loves it. You love it. Which makes you watching your dog love it… a little weird. But the truth is, from humans to cats and dogs and beyond, social mammals adore being gently stroked down their bodies. Whether that body is furry or covered in the finest patina of hair, the results are the same.
California Institute of Technology researchers happened upon the reason for this phenomenon while studying a specific type of neuron commonly found in hairy or furry mammals’ skin. These cells had been discovered in 2007, but their usefulness to their possessors was not yet known.
The solution was to genetically modify mice so that these particular nerve cells would light up when stimulated. The researchers then used a microscope to see which type of stimulus would ring the bell, so to speak:
They tried various types of stimuli to see if they could get the cells to light up. For example, the scientists recorded each time they stroked the hindfoot of the mouse with an artist’s paintbrush. In this way, they could see if the touch was responsible for the nerve signal. Gentle stroking, but not poking or pinching with a tweezer, elicited a response, Anderson and his colleagues report online today in Nature.
Of course however pleasing and even amorous petting can be, science is not often romantic, and neurology even less so. To wit, the solution for determining whether the soft petting actually did feel good was – you guessed it – more genetic modification, rigorous testing and a healthy dose of drug abuse.
The researchers this time modified the mice so that an injection of a chemical would elicit the same response from the nerves as petting. Wow. Give me a shot of that.
So they put the mice in a three-chambered box. In one chamber, they’re shooting up and listening to the Velvet Underground. In the opposite chamber, diddley-shit and Pat Boone.
Guess what? After a few weeks of conditioning, the mice preferred the petting den. Whether this proves that mice prefer petting or have addictive personalities remains an open question in my mind.