Dr. Universe: Why do cats like lasers? -Izzy, 10, MD

Dear Izzy,

Not only do I enjoy answering science questions from kids, but I also like naps, tuna fish sandwiches, and chasing lasers. I wasn’t entirely sure why I like chasing those little red dots. I asked my friend Leticia Fanucchi, a veterinarian at Washington State University.

“Cats like lasers because they are predators and like to chase or hunt anything that moves fast around them,” Fanucchi said.

A zipping red light that quickly switches directions might have a similar motion to a mouse or other critter. The light sort of mimics an animal scurrying around to escape its prey. Even though we cats know the laser is not an actual mouse, it triggers our predatory instinct.

An instinct is something hard-wired into animals—they don’t have to learn it, they just naturally know how to do it. For example, dogs drool when they see food. Birds build nests. These are all instincts and some can help animals survive.

As predators, cats also have a few other tools that are useful for survival: claws and sharp teeth. We also have good eyesight and hearing. Plus, we are pretty fast.

The house cat is actually descended from a wild species of cat, including the European and African Wild Cat. These cats were big hunters. While house cats are more domesticated, we still share that instinct to hunt.

Meanwhile, big cats like lions, tigers, and cheetahs have even bigger claws, teeth, and speed. Some of these animals show at least a bit of interest in laser pointers, too.

It turns out cats big and small aren’t the only ones who like to chase lasers. Other animals seem to be very curious about them. Dogs will chase lasers. Some insects go a little wild when they notice a laser moving. People have even recorded fish following the light in aquariums.

Biologists might call the laser a kind of superstimuli. It really draws in the animal’s attention because it’s so different from anything else going on in its environment. Unlike smart prey in nature who camouflage, the red laser point stands out.

While investigating all kinds of things about cats and lasers, I discovered that house cats haven’t been playing with lasers very long. The first cats were domesticated about 4,000 years ago in ancient Egypt. Some researchers think we might have been domesticated even earlier.

Lasers were only invented about sixty years ago. That might seem like a long time at first, but when you consider how long cats have been domesticated, only a small number of cats throughout history have ever played with a laser. That got me wondering how lasers work in the first place. We’ll save that question for another time.

Sincerely,
Dr. Universe

Dr. Universe: How does land affect the weather? – Isaac, 7, Baltimore, MD

Dear Isaac,

The surface of the earth is covered in all kinds of landforms. We have tall mountains, deep valleys, wide canyons, and scenic shorelines—I bet you could think of a few others, too. A little less than a third of our planet is land and the rest is mostly ocean. Both affect the weather, said my friend Nic Loyd, a meteorologist at Washington State University.

We get different weather patterns depending on a few conditions, such as how much sun the land gets, if the land is near mountains or ocean, and how air circulates through the atmosphere.

If you are out on the ocean, you might not feel a big temperature difference between night and day. But we do feel a bigger difference in temperature on land. Especially when conditions are clear and calm, the weather can be very warm in the afternoon and chilly by the morning. Loyd explains that land normally warms up and cools down more quickly than water.

You can test this out at home. Fill up one plastic tub with sand or dirt and fill up another plastic tub with water. Put them out in the sunshine. Using a thermometer, take the temperatures of the two tubs every ten minutes for thirty minutes. Record your results to find out which one heated up faster. You may want to try this a few times just to make sure your results are accurate. Water actually absorbs at least as much energy from the sun as the land does—but water just isn’t capable of warming up as fast as land, or in your case, sand or dirt.

The different types of land around the planet also impact the weather. One good example is mountains, Loyd said. The air is usually much colder if you are up high in the mountains. That’s also where we see a lot of glaciers, ice, and snow all year long. In the mountains, the air is thinner and it doesn’t trap in the heat very well.

Exactly what covers that land also influences the weather. Forests, cities, plains, or deserts can absorb a lot of the sunlight that reaches them, warming the air above the land. But when land is covered in snow, much of the sunlight is reflected away instead of being absorbed into the land. This also helps keep snowy areas colder.

So yes, the land, as well as the water, affects the kind of weather we experience on our planet. But the weather can also affect the land. Just think of the rain that helps plants grow on farms. Or the sun that gives plants energy they need to grow. Can you think of other ways the weather might change the land? Can you think of how these changes might shape the land over a long period of time? Send your ideas to Dr.Universe@wsu.edu.

Sincerely,
Dr. Universe