It has always been debated whether less-evolved species such as insects have feelings or not. And the subject has been discussed from a wide variety of viewpoints. However, a study has just proven that fruit flies are able to experience something very similar to fear.
California Institute of Technology has conducted a study on fruit flies, that were exposed to various emotion-triggering stimuli, that appear to have an effect on them similar to the one that humans exhibit.
The Caltech scientists explained how complex emotions such as fear are comprised of an entire set of partial emotions, called emotion primitives. Researcher David Anderson who participated in the study explained that there still is no complete definition of emotions that everybody can agree upon, but that this primitive theory is the one viewed as closest to the truth.
Much like a recipe, these emotion primitives gather to form something much bigger than every one of them, namely a fully-grown emotion. Another comparison made was that to secondary colors, such as orange, that are a result of the combination of two primary colors, red and yellow.
The complex emotion studied in the Caltech research was fear. In order for people to better understand the experiment, the researchers have used an example that us humans can relate to, hearing a gunshot.
Everybody can agree that hearing a gunshot will trigger an emotion of fear. But there are certain aspects building up to what we call fear. Firstly, a person will experience valance, a negative feeling caused by the sound of the gunshot, that will cause a second primitive called persistence that implies that a person will start acting differently after hearing the gunshot.
And it all gets amplified, in accordance to the situation and the additional stimuli experienced by the person. For instance, if more gunshots follow after the first, the negative sensation will be amplified and prolonged. This constitutes yet another primitive called scalability.
Or if after the gunshot, a person hears another sharp sound, he will experience a negative feeling even if the sound itself is not one that would normally cause fear, such as a phone ringing or a car blowing its horn. This primitive is called trans-situationality.
And so, the scientists exposed the fruit flies to a shadow in a series of situations. The shadow was made by using a paddle and it was meant to represent an attacker lurking over the them and the flies responded with all the primitives mentioned.
When exposed to the shadows, the flies froze or backed away to find shelter. Those would be valance and persistence. Furthermore, if they were exposed to the shadow more than one time, then their response was exponentially more pronounced, and therefore scalable.
“It suggests that the flies’ response to the threat is richer and more complicated than a robotic-like avoidance reflex.”, said Dr. Anderson.
This study has proven that there is a very high possibility that fruit flies might experience something similar to the complex emotion of fear, since they have been proved to experience all the primitives.
However, the Caltech scientists wanted to make it extremely clear that it will take further research to confirm that fact that will imply the use of a brain scanner. Until then, the study published in the journal Current Biology has put down the groundwork that will lead to this amazing scientific breakthrough.
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