An oft-repeated, and understandable, assumption in such research is that it's a 'tolerance' factor as opposed to some other, less anthropomorphically satisfying, and potentially unpalatable, variable. There is a dearth of research on the motivations behind the feline inclination towards literally biting the hand that feeds.

The violent and aggressive feline reproductive spectacle provides the uncomfortable theory that this 'tolerance' factor may actually be 'arousal'. Pitching this research topic has not yet yielded any funding; or at least any funding that didn't come with conditions with which the researchers felt they could comply.