As I put the over-long article away I said to myself, “Did I really just read 10 pages on rhythmic entrainment?”
Entrainment is simply the ability we humans have of synchronizing with a rhythm. . The concept seemed somewhat interesting at first, but the more I read about it, the more pervasive and important it appeared to be. And so I kept digging.
Oddly, there may be only two species that are able to 'entrain' to music: humans and parrots! While other creatures may enjoy music and will often attempt to move in time, parrots are the only sub-humans that can truly move to the groove.
There are some interesting aspects to entrainment. For example, if you set a few metronomes at different tempos and then put them on a surface that can move a bit, the metronomes will entrain to one tempo regardless of the tempo setting (don't know if anyone's tried this with parrots).
We also see entrainment in everyday situations. People in close proximity often synchronize their breathing, and people living together may entrain their sleep (and other) cycles. Entrainment seems to be everywhere.
A central focus of the above-mentioned article was how entrainment might even apply to ethno-musicology. Rather than inundate you with details, let me focus on two aspects.
Societies tend to have culturally-specific rhythms, which are ingrained from an early age. It’s even possible to determine someone's cultural background by what rhythms they are more comfortable with. For example people who grew up with polyrhythmic music -- as can be found in parts of Africa and India -- can join in instantly, whereas polyrhythms might mystify someone from a western music culture.
There's also the issue of identification. There's a good chance your social group likes the same sort of music. This isn't surprising -- it's the music that people of a similar age and social background grew up with.
Musical preference can also serve as a test for who belongs to the tribe and who is an outsider. My own generation thrived on music, and to this day we seem to be of one mind when it comes to the music of our teens. We lucked out and lived in the golden age of rock, but if you ask around, you’ll likely find that every tribe is pretty sure their music is also the best .