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Did Breast-Feeding Play A Role In the Evolution of Pets?

Like the dolphin who adopted a baby whale, humans have often breast-fed pets.

Photo by Elena Arkadova/123RF
Source: Photo by Elena Arkadova/123RF

Recently, French researchers described a remarkable case in which a female bottlenose dolphin adopted a melon-headed whale calf (Penonocephala electra), and raised it for three years.

Their article in the journal Ethology is only the second documented case of foster-parenting between animals of different species in the wild. (You can watch the researchers’ video here.) But perhaps most impressively, the scientists observed the mama dolphin actually nursing the baby whale.

I was so impressed with the story that I posted a link to a National Geographic article on the dolphin-whale adoption on Facebook. And I suggested this unlikely relationship was analogous to human pet-keeping. One of my Facebook friends did not agree. She responded that the big difference between human pet-keeping and this unusual dolphin/whale relationship was that human females never breast-feed members of other species.

But she was wrong. The surprising fact is that in many parts of the world, there is a long history of women nursing animals. To modern sensibilities, the idea of a woman suckling an animal is, to say the least, weird, and even perverted.

And yet, both of the two most important books on the evolution of pets, James Serpell’s In the Company of Animals and Psychology Today blogger John Bradshaw’s The Animals Among Us, discuss the role of wet-nursing animals by women in the origins of pet-keeping. Indeed, Bradshaw writes, “Far from an aberration confined to one tribe, breast-feeding of pets used to occur all over the world…”

The most extensive academic treatise on the geography and functions of women breastfeeding animals is a fascinating but little known 1982 article by Fredrick Simoons and James Baldwin titled "Breast-Feeding of Animals: Its Socio-Cultural Context and Geographic Occurrence." The authors were particularly interested in regional differences in the suckling of animals.

The Geography of Wet-Nursing Animals

Simoons and Baldwin argue that with some exceptions, breastfeeding of animals was, at one time, found nearly worldwide. The types of animals that were fed, however, varied geographically. On the Malay Peninsula, women nursed baby pigs, dogs, and monkeys, and they usually returned them to the wild once the animals were grown. On the Japanese islands of Hokkaido and Sakhalin, Ainu women suckled bear cubs. The Ainu venerated bears and ceremonially ate them.

John Bradshaw, used with permission (based on MacRitchie 1892)
Ainu woman nursing a bear.
Source: John Bradshaw, used with permission (based on MacRitchie 1892)

Bear cubs whose parents were killed for these sacrificial rites were nursed by lactating women. They would “even premasticate a cub’s food and let it lick the food from her lips.” And in Western Australia, Aboriginals regularly nursed dingos and, occasionally, young possums.

Among the people of the Pacific Islands, the breast-feeding of animals was nearly universal. On New Guinea, both pigs and dogs were nursed. Indeed, Simoons and Baldwin wrote, “The suckling of piglets was so common throughout New Guinea that at least four ethnographers have felt compelled to report that the groups they studied do not engage in the practice.” As was the case in most cultures, these women never ate pigs they had suckled. (“It is the same as eating her own child.”)

In both North and South America, tribal peoples breast-fed pets. Monkeys were the most commonly nursed animals in Amazonia, but the list of species also included dogs, peccaries, and deer. In North America, women were reported to have breastfed puppies, deer, bear cubs, and even beavers and baby raccoons.

But while suckling of young animals was common in Southeast Asia, Oceania, and North and South America, it was rare to nonexistent in Europe, Africa, the Middle East, and the Far East (except Japan).

Simoons and Baldwin offered a couple of explanations for the geographic distribution of animal suckling. The first was ecological. Virtually all of the groups in which the nursing of animals was common did not have domesticated milk-producing animals. Hence there was no alternative source of milk for orphaned mammals.

The second was cultural. Some societies had negative views of creatures that were routinely suckled in other places such as piglets and puppies. Thus the fact that dogs and pigs are considered unclean in some Islamic regions explains why these animals were not nursed by humans in the Middle East.

Why Do Women Breast-feed Animals?

Simoons and Baldwin reported that wet-nursing of young animals occurred in different societies for four reasons.

  • Affectionate Breast-feeding: In affectionate breast-feeding, women elected to nurse baby animals out of “compassion, warmth, love.” These creatures were essentially pets treated like human babies. This form of nursing was most common among the hunter-gatherers of the Amazon and the Malay Peninsula.
  • Economic Breast-feeding: In economic breast-feeding, young animals were nursed primarily for utilitarian purposes, for example, the rearing of a hunting dog. On Polynesian islands where dogs were on the menu, puppies were breastfed in order to improve the flavor of their flesh when they were consumed as adults.
  • Ceremonial Breast-feeding: This rare form of animal nursing was practiced by the Ainu in Japan who raised bear cubs for sacrificial slaughter.
  • Human Welfare Breast-feeding: In these cases, animals were nursed for the benefit of the humans. The most common examples were in cultures in which lactating women breast-fed animals to relieve breast pain. And as Carys Williams and her colleagues pointed out, breast-feeding puppies in Polynesia may even have been used as a form of contraception by extending lactation.

Why Did The Practice Stop?

Needless to say, breast-feeding of animals has fallen from fashion even in cultures where it was once accepted. Animal nursing was never common in Europe because of the availability of milk-producing domestic animals. Simoons and Baldwin believe the near-universal absence of the practice in the modern world is the consequence of the spread of Western values across the globe.

That said, there are a few holdouts. Deer are venerated among the Bishnoi religious group in the northern Indian state of Rajasthan. Lactating mothers in that culture continue to breastfeed orphan or injured fawns. And you occasionally run into news stories like the Colorado woman who “allowed her adorable Labrador pup to suckle from her bosom after he refused to take milk or formula from a bottle.”

Breast-Feeding and the Origins of Pet-keeping.

Simoons and Baldwin argue that breast-feeding was an important step on the path to pet-keeping and the domestication of animals. John Bradshaw is not so sure. He writes, “Just because women in other cultures interacted with animals in ways that seen unfathomably intense to us does not mean they automatically considered them “pet” in the sense that we do.” His point is well-taken. However, I still don’t see much difference between the adoption of a baby melon-headed whale by a nurturing mother dolphin, and the modern penchant for adopting puppies and kittens, showering them with love, and calling them “our babies.”

Postscript. The only other published account of cross-species adoption involved a group of capuchin monkeys which adopted a baby marmoset and raised it for 18 months. See Are Humans the Only Animal To Keep Pets?


Carzon, P., Delfour, F., Dudzinski, K., Oremus, M., & Clua, É. (2019) Cross‐genus adoptions in delphinids: One example with taxonomic discussion. Ethology. 125, 669-676.

Simoons, F. J., & Baldwin, J. A. (1982). Breast-feeding of animals by women: its socio-cultural context and geographic occurrence. Anthropos, 421-448.

Williams, Carys Louisa, Silvia Michela Mazzola, Giulio Curone, and Giovanni Quintavalle Pastorino. "What We Have Lost: Domestic Dogs of the Ancient South Pacific." Annual Research & Review in Biology (2018): 1-11.