Opinion

NEW RESEARCH ON HOW DOGS AND CATS BECAME MAN’S BEST FRIENDS

They have lived in our homes, been members of the family, slept on our laps for over 10,000 years. Yet it is only recently that science has begun to answer how it is that cats and dogs came to be our most prized companion animals – discovering, along the way, how the domestication of cats and dogs actively helped change the course of human history.

“Domestication,” says scientist Carlos Driscoll, “is evolution that we can see.” Driscoll is a researcher at Oxford University and the National Cancer Institute in Maryland, where much of the world’s leading work on cats has been done over the past 30 years. (Cats, like dogs, have their own versions of human diseases – they suffer from feline leukemia, HIV/AIDS, SARS – and so are especially valuable for scientists.) A happy, unexpected byproduct of this research has led to recent discoveries in how and why these two animals yoked themselves to human beings, and vice versa. When did this pair bonding begin, and why? What were the benefits? How long did it take for dogs and cats to become dependent on humans – or are they, really? And what is it that these animals can tell us about not only our biological makeup and evolutionary history, but about what it is to be human?

CATS’ CRADLE

Of all the discoveries made about the evolution of the common housecat, it is the most recent that may be the most surprising: It was the cat – the solitary, enigmatic, aloof cat – who first sidled up to humans and worked hard to be liked. And it is the cat that is believed to be the only domesticated animal to have ever done so. (The rest – dogs, horses, farm animals – forged relationships with humans based on mutual need and benefit; humans met them halfway.) “Cats have no use, no purpose – never did, never have, never will,” says Driscoll. “The only thing they ever did was get used to being with people.” This discovery – that it was cats who ingratiated themselves with humans – was made after Driscoll and his colleagues were finally able to pinpoint when and where the domestication of cats took place: In the Middle East, in an area known as the Fertile Crescent, about 10,000 years ago. It was here that humans began domesticating agriculture, which allowed them to settle down and form villages. The garbage and the attendant rodents attracted wildcats; it was the wildcats that figured out they’d have plenty of food and shelter by behaving themselves who are the ancestors of today’s housecat.

“If there were two kinds of cats – one that would hand your ass to you and one that would not, you’d keep [the calmer] one around,” says Stephen J. O’Brien, chief of the NCI’s Laboratory of Genomic Diversity. O’Brien is also a co-author, with Driscoll, of papers and articles on the topic. “Cats said, ‘This is our chance to get domesticated!’ ” Each of the world’s one billion domesticated cats is descended from the wildcat of the Fertile Crescent, and, says O’Brien, 99% of housecats remain feral, meaning they can survive on their own. “Cats actually enjoy the habitat of humans rather than the humans themselves,” he says.

Different breeds of cat, meanwhile, are only about 150 years old – after wealthy Britons began pursuing fur patterns and colors. Without human intervention, all cats would look like their forebear: a gray mackerel tabby.

So: if looking for a head rub or a cuddle, is your cat just shining you on? “Yeah, definitely, you bet,” O’Brien says, laughing. “I mean, I’m not a cat, I can’t tell you. But I’m synthesizing hard-nosed molecular biology and genetics.” (O’Brien has six cats and two dogs and will not say which he prefers.) Driscoll disagrees, and says “that head-rubbing thing” cats do is both a way for cats to mark their territory – they have scent glands in their cheeks – and a sign of affection. “Cats do like you and are happy to see you,” he says.

In her new book, “Animals Make Us Human,” animal scientist Temple Grandin says both things are true: Cats are social and autonomous, connected to their owners and also, citing one researcher, “like a miniature tiger in your living room.” Grandin notes that cats, unlike dogs, don’t really make facial expressions and are probably unable to read humans’ expressions. (And unlike canines and humans, cats don’t have eyebrows – another hindrance.) She also theorizes that humans may have difficulty reading cats because cats have a whole host of subtle signals, a body language of their own that we can’t see.

Driscoll, however, believes it’s quite possible that cats, who have only lived exclusively indoors with humans over the past 200 years (since the invention of the window), may continue to evolve their rapport with humans – maybe becoming even more dog-like in attention- and affection-seeking. “Crazy cat ladies know no bounds,” he says.

DOG DAYS

Though dogs were most likely the first animal to be domesticated (about 15,000 years ago, in Central Asia) they do have much in common with cats. They, too, are descended from a single wild animal (the wolf, a discovery only 10 years old), were treated as favored companions in ancient Rome (as cats were in Egypt), and bred for variations by humans. (The two earliest breeds of dog were the mastiff and a greyhound-like canine.) Dogs, too, share many diseases in common with humans – more than cats, actually. Cats and dogs enjoy more medical care than any animal other than humans.

And both cats and dogs have undergone an evolutionary process specific to domestication: Pedomorphosis, which is roughly equivalent to arrested development. Cats kept as pets usually demonstrate three behaviors specific to kittens: purring, meowing, and kneading their paws. Wildcats do none of these things. Dogs bark and show submission; wolves do not show submission, and bark rarely. As puppies, dogs stop developing earlier than wolves, which results in features that are similar to those of a human baby: disproportionately big eyes, stub nose, fleshy cheeks – all the features that engender feelings of love and protectiveness in adults. Author Grandin cites recent research that shows dog breeds that look the most like wolves also exhibit the most wolf-like behavior.

The crucial difference: dogs served a purpose. They hunted, stood guard, and/or were killed for food and their pelts. Their domestication was mutual. But for some reason, dogs and their ancestral wolves have some genetic variant that allowed for a different kind of bond with humans. How long did it take the wolf to evolve from wild to domesticate, and to then exhibit loyalty and affection to its owner?

This is the subject of an ongoing study in Russia begun by the now-deceased scientist Dmirti Belyaev. Forty years ago, Belyaev selected 30 wild male foxes and 100 wild female (known as “vixens”), and began to attempt to domesticate them. Forty generations later, says Driscoll, these foxes, raised in captivity and tended to by humans, “are just worthless.” He laughs. “They are sycophantic, rolling over on their backs, looking at faces – they are doing the things that dogs do. Dogs are suck-ups.” Thousands of years of breeding have left dogs dependent on humans for survival. Biologist James Serpell once described the deeply twined relationship between dogs and people this way: “The domestic dog exists precariously in the no-man’s land between the human and non-human . . . neither person nor beast.” Grandin writes, “The natural state of life for dogs is to live with people.” This may be in part due to their ancestry: dogs are descended from pack animals; wolves form nuclear families. They are highly social creatures who need constant companionship and mental stimulation (“fetch” is basically a domesticated version of hunting and catching). “Dogs are a lot more attuned to what people are thinking [than cats],” says Driscoll. “That’s not speculation – that’s true. There have been a lot of studies done on how dogs know what you’re thinking. They look at your face. They look at what you’re looking at, and where. You can direct a dog to retrieve something with your eyes – there are very few animals you can do that with.” Though it’s a cliche, as Driscoll admits, that “any kid can tell you cats and dogs are different,” the ongoing research into the origin of cats and dogs, and how and why they became such integral parts of human civilization, contributes to our own development and survival. For example: knowing that all housecats descended from one specific wildcat means that worldwide medical research yielding the same results indicates a true result.

Learning how cats, especially, came to be domesticated, tells us much the same about humans – about how we ceased to become a nomadic species. It was the domestication of cats and dogs that led to the domestication of the animals we used for travel, for hunting, for food and clothing – marking the beginning of true civilization.

Yet the deepest mystery may never be answered: why did we take so deeply to these two species, and they to us? The discovery of a cat buried with an Egyptian over 9,000 years ago, and a pup buried with a hunter-gatherer in the Middle East about 12,000 years ago, tells us that there has always been emotion involved. (Cats to a lesser extent, but still.) Driscoll, in fact, says that this is his next area of research, to find the genes related to domestication specifically, to begin to answer what disposed these species to us. “No one knows how domestication leads to so many changes,” he says, “in how an animal thinks and acts and intuits, simply by teaching it not to be afraid of you.”