It can be hard to resist a bag of salty popcorn at the movies. Scientists may now be one step closer to explaining why. They have discovered several genes in fruit flies that help the insects detect salt.

All cells depend on salt to survive, and animals need to make sure they get enough of the nutrient. Previous research revealed tiny pores, known as epithelial sodium channels, on the taste buds of rodents and other mammals that respond to salty foods. These particular sodium channels seem to be so important to mice that the animals die when scientists inactivate the system.

Researchers at the Howard Hughes Medical Institute in Iowa wanted to find out if other animals have similar salt-sensing systems. So, they identified genes in fruit flies that they suspected might control sodium channel production. Then, they turned those genes off in a group of the insects.

The mutant flies survived. Unlike regular flies, however, they were equally attracted to water with and without salt, and they couldn’t tell the difference between different kinds of salt.

If people end up having the same kind of salt-detection system as mice and flies, researchers might be able to figure out why we like salty foods so much. Too much salty food can be bad for your health, so the work could also lead to salt substitutes that taste good but are okay for people with high blood pressure.

Even if scientists don't yet know exactly how people detect salt, it's pretty clear that french fries, potato chips, popcorn, and other salty snacks have a natural appeal.—E. Sohn