angry flies

From all indications, the fly on the right in this photograph is angry.

The stubborn insistence of a fly that again and again tries to access our food plate from which we chase it away with our hand can make us believe that the insect feels growing frustration and that its recklessness is born of anger. Perhaps there is some truth in that when the flies’ behaviors are similar to the one described.

Scientists have concluded that flies can become angry and adopt aggressive behavior when something, such as a soft blow, repeatedly prevents them from accessing the food they have detected.

A few years ago, these scientists, specifically the team of biologist David Anderson, from the California Institute of Technology (Caltech) in the United States, carried out a series of experiments of this kind.

The conclusion they reached after seeing the results of their experiments is that a very specific behavior in fruit flies, described as lunging and threatening behavior, reflects an emotion that can be classified as anger.

Flies that behave in this aggressive way, like the one on the right in the photo, feel angry.

(Photo: Eric Hoopfer/Caltech)

Anger therefore appears to be an evolutionarily important emotion, as it is present even in the tiny brain of these flies, which has only about 20,000 neurons. (Fountain: NCYT by Amazings)