Fruit flies may be the bane of a clean kitchen, but for the last century, these little bugs have been a staple in genetics labs. Easy to keep and quick to reproduce, fruit flies have helped scientists understand how genes are carried from one generation to the next and, importantly, how those genes can be influenced over time. And with about the same number of genes as humans, they're extremely helpful in helping scientists understand more about human genetics.

Neuroscientist Eric Hoopfer of California Institute of Technology in Pasadena is studying how fruit flies battle one another. No, it isn't to learn more about how humans can become stronger fighters, rather it's to learn how we process things like aggression and depression.

KQED Science reports:

When the aggressive fruit flies at Caltech fight, Hoopfer and his colleagues monitor which parts of their brains the flies are using. The researchers can see clusters of neurons lighting up. In the future, they hope this can help our understanding of conditions that tap into human emotional states, like depression or addiction.

“Flies when they fight, they fight at different intensities. And once they start fighting they continue fighting for a while; this state persists. These are all things that are similar to (human) emotional states,” said Hoopfer. “For example, there’s this scale of emotions where you can be a little bit annoyed and that can scale up to being very angry. If somebody cuts you off in traffic you might get angry and that lasts for a little while. So your emotion lasts longer than the initial stimulus.”

Circuits in our brains that make us stay mad, for example, could hold the key to developing better treatments for mental illness.

This fascinating video explains how stimulating the same neurons at different intensities can spark either fighting or flirting. The fact that the same stimulus can bring out such different behaviors is one of keen interest to researchers. The information can open up a deeper understanding of the social behaviors of people.

If you're wondering why we might want to know so much more about seemingly basic behaviors, Dr. David J. Anderson, who oversees Hoopfer's lab, reminds us: "Given the public health problem posed by violence, it is surprising how little we know about the brain mechanisms that control aggression... If we wish to solve the pressing problems of violence that plague our Society, it is essential to understand the basic brain mechanisms that control aggressive behavior."

Fruit flies, whether aggressive or amorous, are giving us the opportunity to dive deep into the way the brain works when it comes to emotions.

Jaymi Heimbuch ( @jaymiheimbuch ) focuses on wildlife conservation and animal news from her home base in San Francisco.

What fruit flies can tell us about human emotion
The love and hate waged between fruit flies is helping scientists map the human brain.