Why do we cry? The three types of tears

Whether we cry during a sad movie, while chopping onions, or completely involuntarily, our eyes are constantly producing tears. Alex Gendler tracks a particularly watery day in the life of Iris (the iris) as she cycles through basal, reflex and emotional tears.

Dead stuff: The secret ingredient in our food chain

When you picture the lowest levels of the food chain, you might imagine herbivores happily munching on lush, living green plants. But this idyllic image leaves out a huge (and slightly less appetizing) source of nourishment: dead stuff. John C. Moore details the “brown food chain,” explaining how such unlikely delicacies as pond scum and animal poop contribute enormous amounts of energy to our ecosystems.

The mystery of motion sickness

Although one third of the population suffers from motion sickness, scientists aren’t exactly sure what causes it. Like the common cold, it’s a seemingly simple problem that’s still without a cure. And if you think it’s bad on a long family car ride, imagine being a motion sick astronaut! Rose Eveleth explains what’s happening in our bodies when we get the car sick blues.

The Invisible Universe Of The Human Microbiome

The next time you look in a mirror, think about this: In many ways you’re more microbe than human. There are 10 times more cells from microorganisms like bacteria and fungi in and on our bodies than there are human cells. But these tiny compatriots are invisible to the naked eye. So we asked artist Ben Arthur to give us a guided tour of the rich universe of the human microbiome.