But dogs probably didn’t make enough milk to justify making a dairy breed of dogs.

When it rains super heavily, the soil can get too wet. Waterlogged soil has fewer air pockets—because many of those spaces fill up with water. Under those conditions, earthworms might move out of the soil temporarily, seeking a better place to breathe.

Some ancient insects began to grab prey. Individuals with bigger, stronger legs might have had an easier time.

Some people do eat reptile eggs. But humans spent thousands of years domesticating birds until we have today’s chickens.

A hole in your heart means there’s an opening in the wall between the right side and left side of the heart. That opening allows blood to leak between the chambers instead of following the normal route.

The urine a dog leaves behind is like a smell fingerprint. It’s full of chemical messages like hormones. One whiff of another dog’s urine tells my dog roommate important stuff—like the other dog’s age, sex and health information.

Keeping your goldfish on a regular light/dark schedule will make it happy and healthy. But feeding it at the same time every day may help even more.

The QWERTY keyboard hit the market as early as 1872. It was part of a new device called a typewriter. But nobody is sure why inventor Christopher Sholes organized the keyboard that way.

Watching TV up close won’t hurt your eyes. But your eyes need to focus on close things and far away things. That variety keeps yours eyes working.

Air moves because the sun heats Earth unevenly. Warmer air rises and cooler air sinks. Air molecules flow from places with lots of air molecules to places with fewer—as wind.