Lots of cognitive scientists are studying why humans like, make and listen to music. Carl Zimmer discusses some of the recent research in the Dec 2010 edition of Discover Magazine.

One of the scientists studying music is Robin Dunbar, and Zimmer describes Dunbar’s ongoing work (which extends his earlier work on verbal grooming):

Dunbar has spent much of his career studying bands of primates. One of the most important things they do to keep the peace is groom one another. Grooming triggers the primate brain’s hypothalamus to release endorphins, neurotransmitters that ease pain and promote a feeling of well-being. Our early ancestors may have engaged in similar behavior. As humans evolved, though, they started congregating in larger groups. By the time the average group size hit about 150, grooming was no longer practical.

Music evolved, Dunbar proposes, because it could do what grooming could no longer do. Large gatherings of people could sing and dance together, strengthening their bonds. In a few studies, researchers have found that listening to music can raise the level of endorphins in the bloodstream, just as grooming can.