Evidence of the health benefits of masturbation have bolstered both the religious and evolutionary arguments for jerking off. Recent studies have shown that regular ejaculation can improve fertility, which means that pleasuring yourself isn’t all about instant gratification; it’s also about fulfilling the evolutionary imperative (and for many, the religious obligation) to procreate.
So, asks Slate writer Daniel Engber, if jerking it helps us procreate, wouldn’t it be a positive behaviour from an evolutionary perspective in animals as well? Indeed, he answers. Which is why every creature, from horses and dogs to turtles and birds, are known to do it as well.