But what happens when animals reciprocate the feeling? Well, it's not always so innocent.
You know the story: Dolphin falls in love with woman. Man gets in the way. Dolphin kills man. It's a tale as old as a Disney love story from a dystopian alternate dimension. In 1994, at a popular vacation spot in Sao Paulo, Brazil, a resident dolphin known for his peculiar friendliness towards female swimmers attacked two human males he apparently considered to be romantic competitors. One of the men died of internal hemorrhaging after being butted by the envious dolphin.
This tendency to engage in jealousy-triggered violence is most commonly witnessed in our avian friends. Pet birds such as parrots, cockatiels, parakeets, and even pigeons are widely known to become besotted with their owners. As renowned animal behaviorist and UW-Madison professor Dr. Patricia McConnell told me, parrots are especially susceptible. If the bird is never exposed to another member of its species at the time when it reaches sexual maturity, it may just fall in love with you.
This has some pluses and minuses. On the plus side, your pet parrot may regurgitate food and offer it to you (how nice!). On the negative side, if an unfortunate boyfriend or girlfriend gets in the way of this affection, the bird may squawk at, flap at, or even bite them.
But an animal's adoration for humans can also manifest itself in more healthy ways. Pet birds may be jealous creatures, but they're also known to be protective guardians. There are multiple reported incidents of parrots fighting off burglars, alerting others when a victim is choking, and even imitating fire alarms in order to save their owners.
But where fondness for humans is concerned, dogs are the unparalleled champions. As mankind's leading companion, dogs have kept us warm on the coldest, darkest nights, saved us from under mountains of piled rubble, and led us safely across busy intersections. Dr. Patricia McConnell has written extensively on canine-animal relations and has no reservations about calling a dog's affection for humans by what it really is: love.
"[A dog's] physiology for creating social attachment is so similar to ours, and they behave in ways that, if any human did it, we'd label it love, attachment," McConnell told WhyFiles.org.
Animal love can be both beautiful and terrible, just like the human form. It's a stark symbol of how closely humans and critters are related in the overall scheme of life.