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The Thoughtful Animal

The Thoughtful Animal

Exploring the evolution and architecture of the mind

Ferrets: Man's Other Best Friend

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If a human points his or her finger at something, a dog might infer that there's hidden food, while the chimpanzee remains more or less clueless about the meaning behind that sort of non-verbal communication. As dogs have evolved in a social space occupied by human social partners, they've gained the unique ability not only to comprehend human social-communicative cues, but perhaps even to manipulate humans, and certainly to initiate communicative interactions with humans.

One study found that dogs are more likely to ask a human for food if the human's eyes are visible, suggesting that dogs understanding something about human attention. (They also might be more likely to try to eat from a "forbidden" bowl if a human's eyes are closed.) Unlike wolves, dogs make eye contact with humans in an effort to receive help in solving an "impossible" task. All of this is to say that dogs are suited to socializing with humans in a way that even the other great apes - species more genetically related to humans - are not.

One might suppose that dogs' impressive social cognitive skills arise from experience interacting with humans rather than from genetics, but experiments with human-raised wolves as well as with domesticated goats, horses, cats, and foxes all point towards domestication - that is, genetics - as the root of many of these abilities. If domestication lies at the heart of these sorts of social-cognitive skills, then domestic ferrets should share some of the same social cognitive skills, particularly when it comes to comprehending human social cues, as the others in the domestic menagerie.

Leonardo da Vinci's "Lady with an Ermine" (1489-1490), though actually a ferret. Oil on wood. (Click to enlarge.)

Ferrets are a carnivorous species that have not yet been rigorously studied when it comes to social cognition, or really at all within the field of psychology. "Although their early history in service of man is obscure," write Hungarian researchers Anna Hernad, Anna Kis, Borbala Turcsan, and Jozsef Topal last week in a new paper in PLoS ONE, "ferrets have probably been domesticated for more than two thousand years by selective breeding from the European polecat (Mustela putorious)." Like dogs, they say, ferrets originally were bred for practical reasons like hunting. Their role within human society has since shifted, as they now predominantly serve as pets. If ferrets adapted to a new social ecology within human society as have other domestic species, like dogs and horses, then they ought to respond to humans differently than their wild forebears.

Seventeen domestic ferrets were compared in three experiments to sixteen human-raised wild mustelids and eighteen domestic dogs. (Mustelids include polecats, weasels, otters, badgers, minks, and others. The wild mustelids in this study were hybrids of those species.) Importantly, all the wild mustelids were raised by humans and kept as pets. Any differences in their behavior would therefore be attributable to domestication rather than to being raised by humans.

First, the three groups of animals were compared for their tolerance for eye-contact. The domestic species - ferrets and dogs - tolerated prolonged eye-contact from their owners, but not from strangers, while the wild mustelids did not show this distinction. Ferrets and dogs were also both more likely to accept food from their owners than from strangers, while the wild mustelids made their approach decisions randomly, equally preferring their owners and a stranger (In fact, there was a slight but statistically insignificant preference for the stranger!) In both experiments, domestic ferrets' performance was significantly different from the wild mustelids, but not statistically distinguishable from the responses of the domestic dogs. Rather than sorting along genetic lines, performance in these tasks could be explained by domestication.

Eye contact experiment (left), food preference experiment (right). Click to enlarge.

The third experiment tested each group's response to two types of pointing: momentary pointing, in which an unfamiliar experimenter briefly pointed at one of two containers that could have contained food, but did not make physical contact with it, and sustained touching, in which the experimented physically touched one of the two containers.

In both conditions, as in the other experiments, ferrets and dogs preferred eating from the container that the experimenter had indicated, while the wild mustelids did not display a preference for either container. And, as before, the ferrets' performance was statistically different from the wild mustelids', but not from the dogs' responses.

It is telling that of the sixteen wild mustelid hybrids, a large proportion of them would not even participate in the third experiment; they completely ignored the experimenter. Those that did participate, however, were more likely to have a domestic ferret in their recent ancestry.

The researchers conclude that the domestic ferrets' social-cognitive skills are a result of domestication, and are therefore related to genetic differences between domestic ferrets and their wild cousins, rather than differences in experience. This lends further support to the "syndrome" hypothesis of domestication, which holds that selection for one trait (such as tameness, or tolerance for humans in close proximity) can result in a wide variety of correlated by-products that also emerge as a result of that selection, including behavioral and cognitive traits as well as anatomical and physiological ones. "The fact that domestic ferrets seem to be more 'dog-like' than 'wild ferret-like' regarding their social-affiliative behaviors and responsiveness to human [gestures]," they write, "strongly supports the notion that (at least some of the) domestic species have acquired a set of social skills that improve their chances to survive in human communities."

Hernádi A, Kis A, Turcsán B, & Topál J (2012). Man's Underground Best Friend: Domestic Ferrets, Unlike the Wild Forms, Show Evidence of Dog-Like Social-Cognitive Skills. PloS one, 7 (8) PMID: 22905244

Header image by Alfredo Gutiérrez via Wikimedia Commons/Creative Commons. da Vinci painting via Wikimedia Commons/public domain.

The views expressed are those of the author and are not necessarily those of Scientific American.

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