Many researchers and theorists have been looking for an answer to these questions for several decades. Many have assumed that infants develop a sense of rhythm through their first couple years of life. However, a recent study in the Proceedings of the National Academies of Sciences shed some light on this issue. In this study, the researchers monitored the brainwaves of newborn babies while the babies listened to the consistent beats of music. They found that when the babies listened to a consistent rhythm that suddenly changed, the babies' brains were able to pick up on the change in rhythm (the brain produced something called a mismatch negativity, a brain wave that typically indicates a violation of expectations).
This research demonstrates that the ability to detect rhythm is present at birth and is not learned throughout childhood (as previously assumed). That is, the perception of beats is innate, or built-in, and is done by babies immediately upon birth. This result adds to a growing body of literature demonstrating that many of the components of music can be recognized (at least at the level of the brain) in newborn babies - an impressive feat for such a little one! If you want to jump-start your baby's appreciation of music, check out some of the best baby monitors on the market that can play lullabies and other music!
Winkler, I., Haden, G. P., Ladinig, O., Sziller, I., & Honing, H. (2009). Newborn infants detect the beat in music. Proceedings of the National Academy of Sciences, 106, 2468-2471.