"Cats or dogs?" is one of the oldest questions known to the human race. The two "main" species of pets are very different, and each side has ardent supporters who insist that the other side is wrong.
But people on every side of the debate agree on one thing: dogs, as a rule, are obsessed with humans, and cats ... aren't. Why?
The answer is probably rooted in evolution.
Dogs split from their ancestors, gray wolves, somewhere around 32,000 years ago. Since then, scientific evidence suggests that dogs and humans have coevolved.
Dogs and humans have coevolved.
Coevolution occurs when species reciprocally affect one another's evolution. This phenomenon usually happens when the species have "close ecological interactions" with each other. Since their split from wolves, dogs' brains and digestive organs have evolved in ways similar to those of humans, suggesting that we have been coevolving with dogs for thousands of years (though the exact number of years is debated).
Our coevolution suggests that dogs and humans' survival has been intertwined, to some degree, for a long time. We don't know exactly what that looked like in the early days, but I choose to believe that it was cute.
Additionally, over the years we as a species have selectively bred dogs who love us the most. By purposely breeding dogs who are friendly to humans and practical for us to have around, we've ensured that our present-day dogs come from a long line of human-obsessed ancestors.
Unlike dogs, cats domesticated themselves.
Cats, on the other hand, did not coevolve with humans, and the mere suggestion of it insults them. Instead, cats domesticated themselves. (This probably won't surprise most cat owners.)
We think that cats started hanging around humans roughly 8,000 years ago, or possibly even earlier, but some time after the advent of agriculture. Cats enjoyed feasting on the delicious rodents that were attracted to crops, and humans appreciated the service these cats were providing by keeping the rodent populations down.
In true cat style, cats then spent thousands of years living alongside humans before becoming domesticated. They just saw no reason to rush things. Interestingly, since that time, cats' genes have evolved very little. This stands in direct contrast to their canine counterparts, who are now drastically different from their wolf ancestors. Thousands of years ago, cats decided to start hanging out with humans because it was beneficial to them, and then they didn't change much.
Modern cats, of course, are generally friendly to humans, but most of them haven't developed the levels of off-the-charts excitement toward us that dogs have.
Some people will always prefer dogs, and some people will always prefer cats. One thing is for sure: dogs really want you to choose them, and cats don't care either way.