Darwin assumed that emotions like mother love are available to at least some animals.
A gorilla holds her newborn in her arms and slobbers it with gooey kisses.
A chimp risks her life to protect her newborn twins from a gang of murderous females.
A baby monkey dies. For minutes on end, the mother looks stunned. Then she cradles it, stroking it tenderly and clutching it even more tightly whenever others approach. She carries its body for the rest of the day.
Humans are primates. We know we are capable of mother love. But are non-human primates capable, as well? Are other animals?
Charles Darwin, the nineteenth-century English “father of evolutionary science,” thought that animals closely related to humans can feel love. Whether he was right or wrong about that, he came to appreciate some of the complex similarities between humans and other animals as a result of closely observing a three-year-old female orangutan named Jenny.
In 1838 when Darwin visited the London Zoo, he was struck by how much Jenny’s behavior resembled that of a human child. Jenny was one of the Western world’s first captured apes. On that first warm day and on several others to follow, Darwin spent hours observing her. When the zookeeper teased Jenny, beckoning her with food and then refusing to give it to her, Darwin noted that her tantrum neatly matched the behavior typical of human toddlers. So did her facial expressions. Darwin also got the distinct impression that Jenny had a good sense of some of the words she heard around her. This, too, reminded him of human toddlers; they usually understand language before they can speak it. Darwin noted that Jenny was astonished when she saw herself in a mirror. (Darwin was often dumbfounded by mirrors, too. He was forever aghast at the size of his nose.)
Darwin’s experience watching Jenny helped convince him that humans and orangutans are closely related. He thought that perhaps the two species share a common ancestor. Indeed, Darwin’s essential theory as expressed in his 1859 book On the Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life was that that all of the complex plants and animals of the modern world are the progeny of only a few simple organisms that existed eons ago.
All species are related to all other species. Some are more closely related than others.
From the idea of common genesis, Darwin assumed that the emotions like mother love that humans have are available to at least some animals.
In his 1871 book The Descent of Man, and Selection in Relation to Sex he wrote, “It is certain that associated animals have a feeling of love for each other.” He referred often to the “maternal instinct,” but also wrote of “the love of a female dog for her young puppies.” And he observed that animals of one species express “sympathy” for animals of another. “I have myself seen a dog, who never passed a cat who lay sick in a basket, and was a great friend of his, without giving her a few licks with his tongue, the surest sign of kind feeling in a dog.”
Do Today’s Scientists Think Animals Can Love?
When a gorilla covers her newborn with kisses, when a monkey mourns her dead baby, when a chimp risks her life for the sake of her twins, are the mothers acting on a deep and abiding feeling? Or are they just driven by the “survival of the species” instinct first described by Darwin?
Frankly, the answer depends on which scientist you ask. Even so, it almost doesn’t matter what the nature of the bond between mother and child animals is called. Evidence gathered from many species shows that the as-yet ineffable attachment confers on the young extraordinary benefits in terms of longevity and reproductive success.
For example, red deer who are cared for by mothers throughout their childhood grow longer antlers, which may improve their mating success. Male bonobos achieve alpha status more readily if their mothers are still alive when they try. Being orphaned can shorten the life of a baboon, an elephant, or a chimp, according to research conducted at Cold Spring Harbor Laboratory and now under peer review.
Reproductive success is an especially significant marker. As Darwin explained, an organism’s primary instinct is to act on behalf of its genes’ survival into the next generation. That’s how life continues and evolution happens. Since then, critics have attacked Darwin, but mostly on religious grounds. Very few scientists have quarreled with his basic premise.
The Reproductive Success of Children without Mothers
When measuring for the effect of a mother’s steady care on her children’s reproductive success, a team of primatologists and evolutionary anthropologists from Germany’s Max Planck Institute for Evolutionary Anthropology, from Côte d’Ivoire’s Taï Chimpanzee Project, and from Harvard University in Cambridge closely observed three communities of chimps in the Taï National Park. The scientists were especially interested in learning how animals who lost a mother during childhood fared as reproducing adults. They reported this September in the journal Science Advances.
The team observed each community for an average of almost seventeen years. Because, as is typical of chimps, all females in the communities dispersed at maturity so as to avoid mating with close relatives, the team was only able to collect data about the reproductive success of orphaned males.
Consistently, the researchers found that males who had been orphaned after weaning but before age twelve matured into adults who sired considerably fewer children than did their peers.
· Orphaned males maintained alpha status only about half as long as other males, and therefore had greatly reduced access to fertile females.
· On average, the first offspring of orphaned males were born about three years later than those of their peers.
· Orphaned males fathered about half as many offspring per mating opportunity as did their peers.
· The offspring of orphaned males were less likely to survive the first two years of life.
Seeing clearly that male orphans are generally not lucky at mating and reproduction, the researchers wondered what benefits beyond food provision and defense a mother’s care confers. They surmised that:
· One possibility lies in the health advantages that sons reap from the grooming that mothers and sons provide each other well into the youngsters’ late childhood. Soothing touch boosts production of the hormone oxytocin, which can counteract the damaging effects stress.
· While orphaned sons may find adequate food, with a mother’s help they might consistently feed on more nutritious food that could boost their general health.
· As is true among humans, mothers can provide introductions. They can quiet fights. They can help a child make friends and acquire mentors.
· Day in and day out, hour by hour, mothers can model social competence by bringing children with them as they travel, nest, forage, and engage in a world of community encounters.
If “love” is still not an allowable word to use when describing the mother-child relationships typical in chimpanzee communities, primatologist Catherine Crockford of the Max Plank Institute and first author on the Taï National Park paper suggests an alternative term. She and colleague Roman M. Wittig have found that levels of oxytocin rise in the urine of chimp mothers as they perform nurturing acts like food sharing, grooming, and cooperative defense. As Crockford explained in an email, “Chimpanzee mothers in the wild are incredibly tolerant, patient, attentive — and nurturing to their offspring, for years, even after weaning…. So how about, instead of mother ‘love,’ using ‘nurturing’?”
Not all scientists are quite as cautious as Crockford when describing the emotional capabilities of non-human mammals. Chimps are humans’ closest genetic cousins. Like humans, chimps seem capable of intention, desire, emotion, and knowledge as well as whatever higher-order mental processing is necessary to have close and easy familiarity. They also have limbic systems similar to those that manage emotion and memory in humans. Drawing on her decades of experience with chimpanzees at the Gombe Stream Research Centre in Tanzania, and giving a nod to the work of scientists observing other species, Jane Goodall has commented, “There [is] increasingly compelling evidence that [humans] are not alone in the universe, not the only creatures with minds capable of solving problems, capable of love and hate, joy and sorrow, fear and despair. Certainly, we are not the only animals who experience pain and suffering. In other words, there is no sharp line between the human animal and the rest of the animal kingdom. It is a blurred line….”
For his part, Emory University primatologist Frans de Waal has written the about non-human great apes: “ All three species [orangutans, gorillas, and the chimps and bonobos of the pan species] face similar social dilemmas and need to overcome similar contradictions while going after status, mates, and resources. They apply their full brainpower to find solutions. True, our species looks farther ahead and weighs more options than the apes do, but this hardly seems a fundamental difference. Even if we wield the better chess computer, we’re still all playing chess.”