One might talk about it from the perspective of birdsong, which is used by mates to judge sexual fitness. First a tutee bird learns from a tutor bird, and then

One might talk about it from the perspective of birdsong, which is used by mates to judge sexual fitness. First a tutee bird learns from a tutor bird, and then eventually applies variability to the original song. It's strongly suspected that anterior forebrain pathway (AFP) may be a source of behavioral variability. We naturally age over time, including our vocal musculature, so in some sense we must constantly relearn how to use our muscles to deliver a song. When a bird is deafened its birdsong will naturally drift, but when we precisely damage the AFP along with deafening we find that birdsong remains stable for a longer period of time, until of course inevitably it must drift due to aging vocal musculature.