A goat frolics with a baby rhinoceros. A pig nestles up to a house cat. A rat snake makes nice with the dwarf hamster originally intended as its lunch.

Few things seem to capture the public imagination more reliably than friendly interactions between different species — a fact not lost on Anheuser-Busch, which during Sunday’s Super Bowl will offer a sequel to “Puppy Love,” its wildly popular 2014 Budweiser commercial about friendship between a Clydesdale and a yellow Labrador puppy. The earlier Super Bowl spot has drawn more than 55 million views on YouTube.

Videos of unlikely animal pairs romping or snuggling have become so common that they are piquing the interest of some scientists, who say they invite more systematic study. Among other things, researchers say, the alliances could add to an understanding of how species communicate, what propels certain animals to connect across species lines and the degree to which some animals can adopt the behaviors of other species.

“There’s no question that studying these relationships can give you some insight into the factors that go into normal relationships,” said Gordon Burghardt, a professor in the departments of psychology and ecology and evolutionary biology at the University of Tennessee, who added that one video he liked to show students was of a small and persistent tortoise tussling over a ball with a Jack Russell terrier.

“Even one example raises the possibility that there’s something interesting going on here,” Dr. Burghardt said.

Science has not entirely ignored unusual interactions between species. Biologists have described relationships formed to achieve a specific goal, like the cooperative hunting between groupers and moray eels. And in the mid-1900s, Konrad Lorenz and other ethologists demonstrated that during critical periods after birth, certain birds and other animals would follow the first moving object they saw, whether animal, human or machine, a phenomenon known as imprinting. Dr. Lorenz was famously photographed with a gaggle of “imprinted” geese trailing behind him.

Yet until recently, any suggestion that interspecies relationships might be based simply on companionship would probably have been met with derision, dismissed as Pixar-like anthropomorphism. That has changed as research has gradually eroded some boundaries between homo sapiens and other animals. Other species, it turns out, share abilities once considered exclusive to humans, including some emotions, tool use, counting, certain aspects of language and even a moral sense.

To be sure, some scientists remain skeptical that the examples of cross-species relations offer much more to science than a hefty dose of cuteness.

Clive Wynne, a professor of psychology at Arizona State University, said that the videos he has seen all portray interactions that take place “in a human-controlled environment.”

“To me, that’s what kind of removes what would otherwise be interesting,” he said. “Because it ceases to be directly a story about animal behavior and becomes a story about human impact on the environment, like the difference between gardening and the beauty of natural landscape.” But others see fertile ground for investigation even in bonds formed in captivity or other domesticated settings. “There are so many questions,” said Barbara Smuts, a primate researcher at the University of Michigan who in 1985 shocked some of her colleagues by applying the word “friendship” to describe bonds between female baboons. “We know this is happening between all sorts of species. I think eventually the scientific community will catch up.”


Read the full article "Learning From Animal Friendships" at the New York Times.