"Hey kitty! Fetch! Shake! Roll over! Good kitty."

This is the future of cats.

See, dogs come in all shapes and sizes, from teacup poodles that fit in a purse to great danes the size of small ponies.

Cats — not so much. For centuries, cats have all been about the same size, the same shape. The same assholes.

But that may be changing.

"There's been a real huge increase in breeding different types of cats," says DeAnna Lee, a cat breeder in Colorado.

Over the past 20 years, the diversity of cats has been slowly increasing. There are different kinds: toygers, cats with stripes like tigers. Lykoi, cats that look like werewolves. Sphynx cats, which look hairless.

  [Toyger, lykoi and sphynx cats.]

And then there's the serval.

A serval cat is like a mini version of a cheetah. It's not a kind of housecat; it's its own breed. They're twice as tall and heavy as the biggest house cats, and can weigh as much as an 8-year-old kid.

And they can be trained like dogs, says Chris Comstock, a breeder in Florida who owns four servals, and has a kitten for sale. They'll come when you call them, she says. She puts them on leashes and walks them around.

[The serval kitten Chris Comstock is selling, which has a "puppy dog disposition."]

There are downsides, Comstock says. They're destructive. "One destroyed the bathroom this afternoon," she says. "He found the toilet roll and it was just funny. Miles and miles of toilet paper all over the bathroom." And "We don't think they do well around small children," Comstock says. Plus they sell for $4,500. "They can make an awesome pet but it's not for everybody." 

[Video from one of the most famous YouTube servals, Zeus.]

The quest to create different types of cats — the way there are different types of dogs — is helped by the servals. Servals are bred with regular house cats; their kitten is a savannah cat, which looks like a cheetah with all the rough edges sanded down.

"They're smart like a dog," says Lee, the breeder. "They are extremely smart." She's taught her savannah cats to shake hands and heel — just like a dog.

Will there someday be as many different types of cats as there are different types of dogs? Could be.

First it helps to ask: why have dogs been so different, while cats have been more or less the same?

Two reasons. First, we've been breeding dogs for longer. We've had dogs as pets for 19,000 years, and cats for only 10,000. That allowed us more time to make dogs different.

Second, humans realized early on that dogs are helpers. They're useful for a range of different tasks. Herding sheep and guarding property are very different jobs, and so people bred dogs to herd, like collies;  and dogs to guard, like dobermans; and dogs to hunt, like labradors. Later, humans bred dogs to be cute little pets, which is why there's poodles.

Cats, on the other hand, have only had two jobs: pets and mousers. And since all cats are perfectly good at these two jobs, why breed them to be very different?

Well, now it's happening. "People are taking one breed and mixing it with another breed to create another one," Lee says. Unlike dogs, most of the artificial selection that's creating different types of cats has been taking place over the last 75 years, not the last 10,000. Breeders are breeding cats into novel shapes, not because it's necessary, or because they need cats to do work, but because it's fun. 

"A lot of people want a hobby," Lee says. "They want to show cats of different breeds at shows. Like the Westminster Dog Show, but for cats."

This could be the beginning of a revolution in pets. If humans put effort into breeding cats to be different, and we work on it for thousands of years, then there might be cats as diverse as dogs are.

Cats on leashes. Cats that do tricks. Cats that guard your house. Cats that fetch frisbees. Cats that bring you beers out of the fridge.

If any of that happens, cats videos are about to get a whole lot weirder.