Why We Have Cats
Cats play a crucial role in the human evolutionary story.
Posted November 28, 2017
Let me start with a confession: I miss my cat, Peanut. Back during graduate school in the 1990s, My wife and I found Peanut when he was a kitten, strutting around our neighborhood in Dover, NH, without a collar, tag, or owner to be found. He was a cute little orange guy, riddled with fleas. As it was New Hampshire, it started to get cold outside. And, well, we just had to bring him in.
And while we loved our other cat, Dixie, and have great affinities for the canines in our world, I think everyone in my household to this day, about a decade after Peanut left this earth, would agree that Peanut was the best pet we ever had. He cuddled, he fetched, he meowed, and he got into all kinds of benign mischief that had us entertained each and every day for years.
So you can imagine how devastated we were one day in 2007 when the vet told us that our little Peanut had kitty leukemia and had only a short amount of time to live. We miss Peanut each and every day.
A couple of years ago, I wrote a post on the evolutionary origins of domesticated dogs ("Why We Have Dogs").
Well, it’s time that we give Peanut and his kind their fair share here on the site of Psychology Today. Yes, cats, too, are part of the human evolutionary story.
How Did Cats Come to Be Domesticated?
With a pet that is so common in human households around the world, as an evolutionist, you have to figure that cats originally joined forces with humans because they had something to offer. Interestingly, while dogs joined forces with humans well over 20,000 years ago (see Skoglund et al., 2015), back when humans were primarily hunters and gatherers, the best evidence on the timing of the original domestication of cats shows that felines are a decidedly post-agrarian furry friend.
Evidence of cat domestication in places such as Egypt and Cypress, where several instances of mummified cats being buried with their owners can be found, goes back about 8,000 years, with additional evidence putting the origins of cat domestication back to about 12,000 years ago. Right about when agriculture emerged, which is when people were first ever able to stay put and live in one place, forming civilizations (see Driscoll et al., 2007).
With the emergence of agriculture came storehouses for grains and other products of the work of the early farms. And with a big pile of grains, you’re bound to get mice and other vermin — which were often vectors of disease. You don’t want mice in your grain pile.
Enter the greatest mousetrap the world has ever seen: The feline. Predators to the core, with physiological systems optimized for a fully carnivorous way of life, felines of all kinds are, essentially, killing machines with fur. So when Middle Eastern wildcats (Felis sylvestris) came around to feast on these growing populations of mice, a major symbiotic moment in the history of humans took place. Cats solved a huge survival-based problem for these Hominid ancestors of ours.
The Taming of the Cat
The question now, of course, is how do you get from Middle Eastern wildcat to Peanut and Dixie and Pixie and Francis and all the other cute, little domesticated cats that we have taken into homes over the past 10,000 years or so?
Cats likely became domesticated in a process of “artificial selection” that was very parallel to the process by which dogs became domesticated. With artificial selection, humans essentially choose which animals or plants will be selected for reproduction. So imagine that you are an early farmer in the Middle East, and you notice some wildcats that are helping thin the mouse population on the farm. Which ones will you take into your house and feed? Probably the nicer ones. Probably the ones that don’t bite you or scratch you. Probably the ones that are not afraid of you.
Bingo: Artificial selection for tame behavior. You see, tame behavior in mammals is actually a heritable trait (see Dugatkin & Trut, 2017). And this is actually not a new story. All the evidence suggests that dogs became domesticated by this same process. Early humans who saw the benefits of having dogs selected particular dogs that were cute, sociable, and non-threatening as their favorites. They were brought in and supported by early people. And their offspring were, as tameness is heritable in mammals, even more likely to be tame. And so on and so on across generations.
Interestingly, by the way, along with tameness come some other unexpected features, such as spots and a curly tail and, in some species, floppy ears. But I digress.
In any case, early farmers were more likely to take in cats that were tame, which were more likely to breed and go on to have relatively tame offspring, etc.
But other features must have been selected by these early applied biologists as well. Cats are generally clean and don’t just go to the bathroom anywhere. You have to figure that relatively hygienic cats were preferred. And cats that effectively hunted vermin had to be selected also. This is why now you might have the cutest little fluffy cat ever... that goes ahead and drops off a beheaded bunny on your front porch each morning. Because ancestral humans who domesticated cats selected for both (a) cuteness and (b) killing prowess. Think about that!
Why Cats Seem to Care Less Than Dogs Do
Cats and dogs are different from each other for various reasons. Like cats, dogs are also killers and carnivores. But their killing strategies are always pack-oriented. You rarely hear about a pack of cats, although you often hear about a pack of dogs (or wolves, or coyotes, etc.). Felines were designed to be solitary killers. And the aloofness of modern cats relative to dogs partly maps onto this fact.
Further, humans and dogs have been working together for over 20,000 years; maybe as deep as 40,000 years, in fact. Cats are a post-agrarian creation. They are relatively new, with domesticated cats going back only about 10,000 to 12,000 years. Dogs have had more time to adapt to the particulars of human social behavior. This may be part of the reason that your dog might treat you as if you are the king of England, and your cat might just roll his eyes and yawn when you walk in the door.
Please don’t tell my two dogs, Nico and Cujo, but I have a secret. Deep down, I think I’m a cat person! And if it weren’t for the fact that many of our relatives and friends are allergic to cats, why, I’d have a house full of them. Yes, I'd be that guy!
As is true with dogs, cats are part of the human evolutionary story. When humans began their ventures into agriculture, vermin of all kinds came out of the woodwork. Early domesticated cats came about to solve this problem. And we’ve been together with these furry, delightful killing machines ever since.
Facebook image: Veera/Shutterstock
Driscoll, C. A., et al., (2007). The Near Eastern Origin of Cat Domestication. Science, 27, 519-523.
Dugatkin, L. A., & Trut, L. (2017). How to Tame a Fox (and Build a Dog): Visionary Scientists and a Siberian Tale of Jump-Started Evolution. Chicago: University of Chicago Press.
Skoglund, P.; Ersmark, E.; Palkopoulou, E.; Dalén, L. (2015). "Ancient Wolf Genome Reveals an Early Divergence of Domestic Dog Ancestors and Admixture into High-Latitude Breeds". Current Biology