Cats – Part 2

Why cats appeal to humans and how cats became semi-domesticated.

Abigail Tucker, in her book The Lion in the Living Room: How Cats Tamed Us and Took Over the World, explores how humans came to accept cats as part of their domestic environment:

When you get down to it, it’s hard to showcase cats’ contributions to society. Cats don’t detect IEDs, retrieve the drowning, or guide the blind. So why are there so many more cats than dogs padding around the planet today? Why do American households include some 12 million more cats than dogs? … Cats, it seems, transcend the practical.

For one thing, Tucker explains:

[C]ats look uncannily like us. Even better, they look like our infants. Their oft-cited “cuteness” is not an arbitrary or benign quality, but a set of highly particular and powerful physical features that scientists have taken the trouble to tease apart and study. House cats are blessed with a killer set of what Austrian ethnologist Konrad Lorenz calls “baby releasers”: physical traits that remind us of human young and set off a hormonal cascade. These features include a round face, chubby cheeks, big forehead, big eyes, and a little nose. As with our own helpless neonates, the “baby releasers” of other animals cue a pleasurable, drug- like “oxytocin glow” in human adults and trigger a set of nurturing behaviors, including enhanced fine- motor coordination that prepares us to cradle a baby. Pet- keeping has thus been called a “misfiring of our parental instincts.” Or as the evolutionary biologist Stephen Jay Gould suggests, we are “fooled by an evolved response to our own babies and we transfer our reaction to the same set of features in other animals.” … [H]ouse cats, including adult ones, and even the original wild lybica, just naturally happen to resemble human progeny, without any engineering at all. Part of it is their size, which— at an average of about eight pounds— is of precisely newborn proportion … As big as cats’ eyes are, their placement may be even more fortuitous. Many other cuddly animals, like rabbits, have eyes on the sides of their heads, which allows for a wider field of vision, and even dogs’ eyes are slightly more off- center. But cats are ambush predators. To pounce upon fast- moving prey, especially at night, they need to be able to judge distances, so they evolved the best binocular vision of any carnivore. This ocular strategy requires overlapping fields of view, so cat eyes face forward, planted front and center in their heads … So a cat’s features are a perfect cocktail of cuteness, yet they still look a whole lot like the animals that once slaughtered our ancestors. A cat’s face is the face of a supreme predator, but it is also the face of a child, and there’s a mesmerizing tension in that combination … [R]aw cuteness, combined with inborn boldness, helps explains how the cat got a paw in the door when so many other species stayed out in the cold.

Cats even make sounds like human babies. As Tucker writes:

Part of it is sound— the cat’s meow is reminiscent of a baby’s cry, and studies show that cats may have modulated their vocalizations over time to mimic the cry more precisely.

Despite their cuteness, cats have a protein that causes some allergic reactions in humans (including me). As Jonathan Losos writes in his book The Cat’s Meow: How Cats Evolved from the Savana to Your Sofa:

Worldwide, twenty percent of people are allergic to cats. For many, exposure to cats causes itchy eyes, sneezing, and congestion. For some, however, the reaction can be much worse, often leading to severe asthma attacks that require a hospital visit. Such allergies are the result of a protein that occurs in cat saliva—infelicitously referred to as “Fel d 1” (pronounced “fell-dee-one”). When cats groom themselves, the protein gets on their skin and fur, then dries and flakes off in dander, joining the dust mites occupying our homes … More recently, Nestlé Purina developed a cat food that reduces the amount of allergen a cat produces by nearly fifty percent. The kibble contains a protein found in eggs that binds to Fel d 1 and prevents it from attaching to the molecules in the body that trigger an allergic response.

Cats’ cuteness and increasing tameness led to the semi-domestication of cats. As Thomas McNamee writes in his book The Inner Life of Cats: The Science and Secrets of Our Mysterious Feline Companions:

The idea of taming wild creatures to serve human uses came along very recently in our species’ history. The most important of our animal familiars—horses, pigs, cows, sheep, goats, chickens, and so on, the barnyard crowd—began to be confined and bred for human uses only about twelve thousand years ago. Dogs have been around a lot longer, possibly as long as forty thousand years. Cats, as we’ve seen, are newcomers, the first fossil evidence of domestication dating only to five-thousand-odd years ago … Then there’s the question of what “domestication” means in the case of cats. All the other domestic animals differ radically from their wild ancestors. The leading scholar of cat ancestry, Carlos A. Driscoll, and his colleagues write in a study of cat genetics that our house cats differ from their progenitors only in “behavior, tameness, and coat color diversity.” Any domestic cat can interbreed with a North African wildcat and produce viable kittens … The primary evolutionary force the geneticists found was “selection for docility, as a result of becoming accustomed to humans for food rewards.” In another article, Driscoll and colleagues do a tidy job of summing up the likely story of how the wildcat became the domestic cat and still stayed wild at heart: “Considering that small cats do little obvious harm, people probably did not mind their company. They might have even encouraged the cats to stick around when they saw them dispatching mice and snakes. Cats may have held other appeal, too. Some experts speculate that wildcats just so happened to possess features that might have preadapted them to developing a relationship with people. In particular, these cats have ‘cute’ features—large eyes, a snub face and a high, round forehead, among others—that are known to elicit nurturing from humans. In all likelihood, then, some people took kittens home simply because they found them adorable and tamed them, giving cats a first foothold at the human hearth.”

Tucker points out that since cats were never bred for the purpose of serving humans to nearly the extent as dogs, cats have retained their essential genetic and behavioral profiles:

The difference between dog breeds and cat breeds (or lack thereof) highlights our historical rapport with each companion animal. First off, dogs were domesticated thousands of years before cats, and we’ve been putting selective pressure on dogs for much of that period; archaeological sites suggest that dogs have come in different sizes since hunter-gatherer days. In addition to getting a head start on cats, dogs were largely hostage to their masters’ decisions in ways that cats were not. Since dogs (unlike cats) depend so heavily on us, people got to decide which dogs got the best food, and—to a degree, at least—who mated with whom. As a consequence, dogs ceded control over their own DNA long ago. This tight genetic leash helps explain why today so many dogs—a staggering 60 percent of the American pet population—are purebreds, and why almost all of what we call “mutts” are mixtures of various pedigrees. (It’s thought that less than 2 percent of cats worldwide have any purebred ancestors.) … By not outsourcing their own survival, and handling hunting and kitten-rearing independently, cats flouted our rules and escaped our meddling.

As Losos writes:

The domestic cat originated from the North African wildcat, and only from the North African wildcat … [T]o understand domestication of the cat, we need to look specifically at the North African wildcat … Domestic cats are derived from North African wildcats, and North African wildcats are genetically distinct from other wildcat subspecies … The fact that wildcats and domestic cats readily mate in the wild and produce fully fertile offspring means that by the standard criterion, domestic cats and wildcats belong to the same species … they interbreed readily and their hybrid offspring can be hard to distinguish from non-hybrid members of either species. This lack of differentiation highlights how little the domestication process has moved cats from their wildcat roots.

Losos describes the process by which cats became semi-domesticated as follows:

The earliest evidence of cat-human association, dating to about ninety-five hundred years ago, comes from two graves on the island of Cyprus. One of the graves contains a human. Sixteen inches from the person’s feet was a second, smaller grave containing an eight-month-old cat, carefully laid on its side and well preserved. The person was buried with prized objects including axes, polished stones, and ochre, which suggests that the cat was a treasured possession as well. The large size of the cat also suggests that he was well fed, further evidence that he may have been a tame household animal, perhaps even a beloved pet … Across the many species that have been domesticated— from ducks to dogs to donkeys— two general paths have been taken. In one route, humans took charge from the outset, controlling the animals and, sooner or later, directing their breeding. In some cases, this occurred gradually, involving species that humans originally hunted, but through time started to manage in herds by limiting their migrations, enclosing them in large areas, and taking care to avoid killing females so that the herd would grow more quickly. Eventually, people began to direct the reproductive process, choosing which individuals could reproduce based on the possession of desired characteristics. The domestication of many common barnyard species such as cattle, goats, and sheep probably began this way. Obviously, this managed population route doesn’t apply to cats. Herding cats? The thought is laughable, and there isn’t any reason to suspect that humans captured wildcats and started selectively breeding them. In the other route to domestication, the animals took the lead in adapting to living with us. As human civilization emerged, our habitations provided opportunities in the form of food, shelter, and safety from predators. Many species took advantage and became “human commensals,” living in our midst and benefiting from our largesse, some to our great displeasure (think rats and cockroaches). In some cases, this association continued into domestication as the animals slowly began to depend more deeply on humans. They adapted to live in close association with us; in turn, we more intentionally provided resources and, in many cases, began making decisions about which individuals could reproduce. Wolves, for example, may have originally been attracted to scavenging in refuse pits near human settlements. The boldest, least fearful members of the pack may have had the advantage because they would be spooked less readily and thus would get more food. In turn, kindhearted humans may have started throwing scraps to the wolves, further favoring the friendliest—or at least most human tolerant—members of the pack. Perhaps wolves began to see the village as their territory and started defending it against other animals by vocalizing when someone or something came near. Humans may have begun seeing value in having the wolves around and so treated them even more nicely. The two species became closer. Generation after generation, those wolves least afraid of humans would have benefited the most and would have had more offspring as a result. In due course, the wolf transformed into the dog. Once they were living among us, we eventually started choosing which dogs could reproduce; dog breeds sculpted to serve different purposes were the outcome. Most researchers paint a similar picture for the domestication of cats. About ten thousand years ago, agriculture began. People transitioned from living in a hunter-gatherer lifestyle—constantly on the move looking for plant and animal food—and settled down to become farmers. This was the dawn of the Neolithic revolution, and it occurred first in an area known as the Fertile Crescent, encompassing what is today parts of Iran, Israel, Syria, Turkey, and other countries. One of the advantages of an agricultural lifestyle is that when conditions are good, food can be grown in ample quantities and stored for leaner times. But in nature, opportunities rarely go unexploited. The archaeological record reveals that rodents of various sorts quickly moved in to take advantage of the bountiful food source sitting in storage. The Fertile Crescent lies within the natural geographic distribution of the North African wildcat. And just as rodents exploited the newfound availability of seeds and grains, wildcats took advantage of the new abundance of one of their favorite menu items … Imagine, then, what happened when the first human settlements emerged. Suddenly, there were clusters of people living in an area. Some wildcats, the more cautious ones, wouldn’t have anything to do with the villages and stayed away. But more adventurous or curious cats might check them out, even hang around. These cats would have been rewarded by the extra food they discovered in the form of plentiful rodents; perhaps scavenging from human trash piles also added to their diet. In addition, because larger predators probably avoided these settlements, wildcats may have been safer living there than elsewhere … More food and fewer predators translate into longer lives and more offspring. Natural selection would have favored the evolution of cats that were not afraid of people and that were attracted to living among us. Presumably, humans would have tolerated the cats, perhaps even encouraging their presence for their pest-control services. The cats, in turn, would have evolved not only to associate with humans, but also to adapt to new circumstances. In particular, the abundant food would have led to the presence of many cats. Notoriously solitary in their former settings, settlement cats would have needed to change their ways to suppress their anti-social tendencies. So how did cats go from household hangers-on to treasured pets? It’s not hard to imagine what happened next. Perhaps people tried to attract cats by providing food and shelter so as to benefit from their rodent-catching skills. In turn, the friendliest cats got extra food and people started valuing having them around just because they enjoyed their presence. Natural selection favored the cats that interacted most effectively with people. Presumably, this led cats to be better taken care of, and thus to live longer lives and have more kittens. Any genetic mutation that made a cat friendlier to humans would be favored and would spread through the population. Before long, Felis silvestris lybica transformed into Felis catus.

In the next essay in this series, we’ll explore the geographic story of cats’ semi-domestication.