The assumption here is that there is a sort of sampling going on. I doubt the ears sample, they act like a filter as stated earlier. If anything samples its likely the brain, but if there's a prefilter on what we're sampling then aliasing is unlikely to occur.
I don't understand the anatomy, so its just best guess. But for aliasing to occur there has to be sampling. I am curious, however, how the eyes alias. What is it they alias? What is their sampling rate, what do you define as aliasing?
Are they aliasing in spatial frequency? Are they aliasing spatial objects? Certainly they don't have very fine resolution otherwise they'd act like a microscope, but coarse resolution doesn't imply aliasing.