Neuroscientists subjected volunteers with amusia -- difficulty telling different melodies apart and remembering simple tunes -- to shifts in pitch comparable to those that occur when someone plays one piano key and then another. The volunteers were unable to discern a difference between the tones. But the volunteers were able to track timed sequences of musical tones and perceive slight changes in timing.
The statements above, if true, most strongly support the hypothesis that whereas perception of timing can apparently be learned, discernment of pitch is most likely innate.