It is impossible to find out whether fruit flies are capable of feeling emotions, but new research suggests that they can experience a fearlike state.
Researchers from the California Institute of Technology have undertaken a study into fruit flies and their response to visual threats, with incredibly interesting results, writes Sindya N. Bhanoo for The New York Times.
Building blocks of emotions
“When a fly responds to a visual threat, it isn’t just a robotic reflex; there is some sort of internal state that develops,” said study author David J. Anderson, a biologist at the California Institute of Technology.
Emotions are made of building blocks known as emotion primitives, which include persistence and scalability. “If you’re hiking and hear a rattlesnake, your heart is going to pound and you experience fear long after the snake is gone,” Dr. Anderson said. “That’s persistence.”
Furthermore seeing 10 rattlesnakes will make you more fearful than just seeing one, and this gradation of an emotion is known as scalability.
Impossible to say whether fruit flies feel fear
In order to carry out their experiment Dr. Anderson and his fellow researchers placed some hungry fruit flies inside a chamber with food, before passing a shadow over the food multiple times. Each time the flies reacted by jumping and moving away from the shadow.
The flies kept on running even after the last shadow passed over the food, and the researchers stated that this showed persistence. Scalability was also evident due to the fact that the flies ran and jumped more quickly as the number of shadow passes increased.
Although the observations point to the idea that the flies are experiencing fear, Dr. Anderson says that it is impossible to draw that conclusion. “We can only know that by verbal report,” he said. “So we can’t scientifically study feelings in any creature but a human.”
The results of the study were published in Current Biology. Despite the fact that results suggest that the building blocks of emotions are present in fruit flies, scientists cannot say that they genuinely feel fear.