The human ability to keep a rhythm is down to the rhythmic values of our own existence, starting with the heartbeat of our mothers while we are in utero. After we are born, we become aware of our own heartbeat, which is different at first from our mother's. Then, as we become less aware of this, we become aware of the rhythms in the world around us: diurnal rhythms, the rhythms of varoius natural sounds, and so on.

Other animals are also capaable of keeping rhythms. The primates, of course, are our nearest relatives and there appears to be some evidence of their ability to keep rhythms. But look at any animal that utilizes singing or dancing in order to attract a mate, define or defend territory, and so on. These animals are demonstrating the same ability to keep rhythm as ourselves. Basically, any animal that is aware of its own heartbeat will demonstrate a rhythmic ability, being it only a wagging tail or an extravagant nautch dance.

Our world is full of rhythms. Rhythm of day and night. Rhythm of tides. Rhythm of the seasons. Waves.

So - animals also have internal rhythms. Heart beat. Walking. The different rhythms of various gaits of animals. Circadian rhythm. Beating of cilia in microscopic organisms.

Plants also have rhythms too.

So what counts as "keeping a rhythm" in an animal? Perhaps vocalisation, or body actions that are "leisure activities" not directly connected to survival as e.g. walking is or the heart beat?

If so then rhythm in the human sense of e.g. recognisable pattern of say 4 beats to a measure or 3 beats to a measure seems to be an especially human trait. Also ability of humans to synchronise with each other while playing music.

Some bird song may repeat in cycles, and anything which repeats in a cycle has a sound of rhythm to a human - but whether it really counts as rhythm I don't know - it might just be that the bird is repeating it like a recording in a loop. Similarly a woodpecker drumming - is that keeping a beat or is it just a repeating cycle, behaviour in a loop?

Some birds and animals can keep time with human generated music. Particularly, primates, elephants and parrots. Example, Snowball the dancing cockatoo:

http://www.scienceline.org/2010/02/they-got-the-beat/

I expect it has some survival value as it helps us to learn to cooperate and to work with each other. In many cultures people sing as they work and the singing helps with the rhythm of the work, also makes it pass more quickly and enjoyably and as a result you get more work done or do it better.

Though not everything we do has to have survival value. Evolution may lead to a creature with sense of curiosity, play, fun, sympathy etc and though in general taken as a whole, all those things probably have survival value for the species and on average for individuals within it, as we well know many things we do as individuals don't seem particularly oriented towards survival. I.e. survival of the fittest may have at least partly shaped our bodies and emotions - giving us bodes and ways of working with the world which make it on the whole easy for us to survive in our ecological niches. But survival doesn't need to motivate us as individuals, as we well know. E.g. thrill seekers, or altruistic people to give examples.

Same for animals, though fitted to survive, doesn't mean that everything they do is of survival value.

So - though it may well be of survival value, music doesn't have to have survival value to occur.