Recently I wrote about grief in animals showing that many animals anguish over their losses and that we're not the only animals who bereave, display deep sadness, or who engage in rituals after losing close friends or loved ones. Now let's consider love, a troubling and mysterious emotion. People don't hesitate to say they love another human or nonhuman animal and then harm them. I'm glad they don't love me.
Animals feel a wide range of emotions, including each of Charles Darwin's six universal emotions: anger, happiness, sadness, disgust, fear, and surprise. It's important to remember that there differences among species in how they express their emotions (as well as perhaps in what they feel), and that there are also differences among individuals of the same species. Not all dogs or chimpanzees experience and express joy, grief, or jealousy in the same way. Research has shown that, as with humans, each individual has his or her own "personality." Animals can be bold, shy, playful, aggressive, sociable, curious, emotionally stable, or agreeable; they can be extroverted, introverted, dominant, or submissive. Individual and species differences make the study of animal emotions more difficult and challenging, but they also more exciting. As the saying goes, it takes all kinds of people to make the world go 'round, and the same is true about the different "personalities" within the social world of animals.
It's sometimes easier to see and understand emotions in animals than in humans because animals don't filter their emotions. What they feel is clearly written on their faces, publicized by tails, ears, and odors, and displayed by their actions. Animal emotions are raw and out there for all to sense — to see, hear, smell, and feel. Anyone can tell. For some, like the people who deliver packages to my home, it's a necessity.
Humans have struggled to understand and define love since the dawn of consciousness, so what possible hope is there that we can understand and define love in animals? And yet, though we don't truly understand love, we do not deny its existence, nor do we deny its power. We experience or witness love everyday, in a hundred different forms; indeed, grief is but the price of love. Since animals grieve, surely they must feel love too.
Love is perhaps the most complex of all emotions, given its bewildering variety of forms and shadings. On this landscape, where science and poetry meet, we find love that is romantic, parental, filial, and erotic, and we see love express itself as friendship, loyalty, affection, tenderness, devotion, commitment, and compassion.
If I were to chance a definition, one that we could use to examine animal behavior in search of love, I'd say that love means preferring the close company of another individual, seeking them out, and if necessary protecting and caring for them. It means forming and maintaining strong and close reciprocal social bonds and communicating your feelings with your loved ones. Not exactly poetry, but it's a start.
There's considerable evidence that many animals are capable of feelings that run the gamut of the varieties of love, and the latest science argues for the existence of love in many different species. The brain machinery of love — the microanatomy and neurochemistry that allow us to feel love — is similar or identical to that of numerous other animals. Once again, science is catching up with what our intuitions already tell us, and in the following sections, we will look at love that is romantic (that involves selecting and keeping a mate), maternal (that involves parent-child bonding), and filial (that involves love between siblings or friends).
Helen Fisher, author of Why We Love, put forth what she calls a "immodest proposal" concerning the evolution of love: "All these data lead me to believe that animals big and little are biologically driven to prefer, pursue, and possess specific mating partners; there is chemistry to animal attraction. And this chemistry must be the precursor to human love."
The most devoted mates are not necessarily our closest kin, the great apes, or other mammals. More than 90 percent of bird species are monogamous, and many mate for life. Fewer mammals are monogamous, and the nonhuman primates appear comparatively callous when it comes to commitment. Chimpanzee males, for example, don't spend much time courting, mating, or remaining with a female whose young they've fathered. When males aren't needed to provide protection or food for their mates or their offspring, they frequently try to mate with as many females as possible. Does that sound like any human males you know?
Animals communicate in a wide variety of ways including scent. Scientists may not be very adept at using their nose, but not so other animals. Scent can be a very powerful communicator, as is made clear in the following vivid description of a male elephant experiencing what is called "musth":
He is a hot-blooded, 30-year-old male in peak physical condition. He has mucus oozing from his cheeks and green urine streaming down his legs. His penis has a green sheen to it and he gives off a smell that can be picked up half a mile away. He wafts his ears back and forth and makes a low rumble. He looks confident: after all, many females find him irresistible. Sounds familiar? Hopefully not. He is a male elephant in musth — something like a state of rut. Sexually mature bull elephants go through musth for a one to two-month period every year. They don't exactly hide it, excreting a cocktail of chemicals from a bulbous gland on their cheeks that can swell to the size of a basketball, passing more than 300 litres of urine a day (equivalent to 24 buckets), and — not surprisingly — smelling like a herd of goats. What's more, during this dramatic advertisement of his sexuality the male appears to undergo something of a personality change; indeed, the word musth is derived from a Persian word meaning drunk. They become very aggressive and obsessed with sex, probably as a result of their high testosterone levels, which can increase by up to 60 times.
A male elephant in musth isn't an animal with whom you'd want to cross paths. What's interesting here is not only are there rapid and obvious personality changes during musth, but also that a male in musth can communicate his intentions clearly and openly to females in whom he's interested and to other males. "Musth is the elephant version of expensive aftershave and a flash car. It is thought to inform males and females alike of an elephant's age, status and reproductive health, and also increases a male's chances of reproductive success."l
The chemical that does it all is called frontalin, which is secreted by sweat glands in the elephant's cheeks and also shows up in their breath and urine. A male proclaims his intentions and prowess, females assess his reproductive fitness, and other males judge how strong he is before picking a fight. The precision of this signaling seems to be unique among mammals, but it's likely that non-mammals also use odors to show their intentions.
There's also compelling evidence that fish also make choices about mating. They're not automatons. University of Louisville biologist Lee Dugatkin has identified what he calls "guppy love." Dugatkin discovered that males change their behavior and become bolder in response to a predator when there is a female around, because females find bold males more attractive. Even among fish, it seems like males will risk it all for love.
