There is a well-worn ‘bloke joke’ about pets. Who loves you more, your wife or your dog? Obviously your dog, because if you lock both your wife and your dog in the boot of your car, when you return it is not your wife that is glad to see you.

Why should animals love us, given the appalling treatment we mete out to the animal kingdom? Dogs have been selectively bred to be our friends and, having been bred for it, naturally excel at it. But other animals, too, show great affection for humans, affection that is warmly, sometimes passionately, reciprocated. Again, why?

Jacky Colliss Harvey brings an impressively eclectic mind to bear on this question. It has become fashionable to refer to pets as ‘animal companions’. Colliss Harvey neatly turns this idea around in her title and looks at us as closely as she looks at our pets. She studied