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9/3/06

Dogs and Cats Evolved With Humans



Cats (and Dogs) Evolved With Humans


Long, long ago wolves became dogs because of their usefulness to the human species, and, of course,
because humans were useful to canines. At night they barked at any threat approaching the fire around which humans slept. Or, they helped track quarry. Or, they could take down an animal so that an early human could move in with a spear for the kill. By their assistance they insured they also got some of the meat.

Wolves are social creatures; so are dogs. Humans became the pack they ran with. Dogs make people feel special, which is a trait inherited from wolves. In a wolf pack, alpha wolves are always treated "flatteringly" by beta wolves. To preserve their position in the pack, the betas lick the alphas. They crawl toward them, bow their heads, expose their stomachs, tuck their tails. This helps preserve wolf society, which is to say pack hierarchy. In your home, you are alpha, so to speak. Dogs apparently came to co-exist with humans during the hunting-gathering phase of pre-history. In this phase dogs would have been valuable to a nomadic group because of the behaviors already mentioned.

Of course, dogs' devotion and loyalty also served them well. Genetically bred into generations of canines, these attributes helped served to cement the relationship with humans. You might say that by this means the dog manipulated humans to its purpose, just as they used it.

Cats, now, they are another matter. Almost regally aloof, they show up when they want to be fed, or need a warm lap. They don't warn of strangers at the door. They would not serve as companions on a hunt. Their chief attribute seems to be "What's in it for me?"

So how did their fate, like the dog, become inextricably linked to that of people?

A quite plausible explanation has felines co-exisiting with humans at about the time people shifted from hunting and gathering to permanent settlements. Cats could keep grain sheds and other food storage sites safe from rats and mice. They came on the scene later than dogs.

But how did the relationship with humans become permanent?

A partial answer is that like dogs, they developed their own way of manipulating people to their own ends.

A recent study suggests they have adapted their meows to better communicate with humans.

"Cats are obviously very dependent on people for their needs," says Nicholas Nicastro, a graduate student who is working under psychology professor Michael Owren at Cornell University's Psychology of Voice and Sound Laboratory. "I think cats have evolved to become better at managing and manipulating people."
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Nicastro


  • recorded more than 100 different meows from 12 domestic cats (including two of his own).
  • brushed cats beyond their patience for brushing.
  • solicited various sounds from the cats by placing them in different scenarios such as waiting beyond feeding time before feeding them, putting them in empty rooms with the recorder and waiting.
  • listened for contented meows by taping them when they were in a good mood.

    Then he played the recordings to two sets of people, a group of 26 and a group of 28.

    The 26 people rated meows for pleasant sounds. The 28 people rated meows for urgency.

    Pleasant-rated meows were shorter, higher pitched, and changed from high to low notes.

    Urgent meows were longer, lower-pitched and changed from low to high notes.


    Nicastro suggests that cats may have developed different kinds of calls to "hook into human perception tendencies" and alert us of their mood and needs. He points out the animals have certainly had time to adjust for people.

    Ancient Feline Friends. Records from ancient Egypt suggest that bonds between cats and people date at least as far back as 5,500 years ago when Egyptians began domesticating wild cats. The animals quickly became treasured pets and were honored in artwork for their snake- and mice-hunting skills. By 1500 B.C., Egyptians began regarding cats as sacred and it became a crime, punishable by death, to kill one.

    Today, about 90 million cats are kept as house pets in the United States alone.

    Nicastro points out that since cats have shorter life spans than people, they've had many more generations to evolve ways of manipulating their owners through their calls.

    The suggestion of a co-evolution between people and domesticated animals is not new.

    Other studies have found that dogs are highly skilled at following the gaze of people (possibly to spot food). And a horse known as Clever Hans demonstrated in the early 1900s how horses can be keenly sensitive to the body language of their masters. The horse's owner convinced people that Clever Hans was psychic when it correctly answered questions by tapping out coded answers with its hoof. Later studies revealed the horse was responding to subtle twitches and changes in posture of its owner.

    While researchers say it's possible that cats may have evolved in a similar way to better communicate with people, they caution it's easy to jump to conclusions.

    "It's conceivable they developed ways to communicate with people since they've interacted with people for so many years," says Douglas Nelson, a professor of bioacoustics at Ohio State University. "But the cats could also have evolved different calls to communicate with each other."

    Screeching Ancestors. To zero in on possible human influence on the domestic cat, Nicastro went to a zoo in Pretoria, South Africa, and recorded the calls of wild desert cats (the animals thought to be the ancestors of domestic cats). He's still analyzing the sounds and plans to have people screen them, but his preliminary findings reveal very different vocalizations.

    "They're much harsher and far less musical-sounding than domestic cats," Nicastro says. "When I've played the sounds for other people, they think they're leopards. They say they sound like cats on steroids."

    Why bother studying something that probably a lot of cat owners might have already guessed? Because it's not really been done before, says Nicastro. He says the field of animal behavior and communication is rich with studies on rare and exotic species, but contains surprisingly little data on cats.

    As he says, "We probably know more about obscure monkeys in Africa than we know about the animals hanging out in our own kitchens."
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    Excerpt from ABC News.com, sci/tec section, 14 May 2002: Cornell Researcher Seeks to Prove How Cats Manipulate People
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