Saturday

We all were exposed to a situation where our excuses for not showing up for a party or a meeting seemed fishy to the others. Although the term "fishy" bears a negative meaning in most cases since it likely originated from the fact that fish are slippery and smell bad after a while, things might change after a recent scientific study showed that fish get in fact emotional, just like humans do. Well, sort of!

Studying emotions in animals has been intriguing biologists for decades. However, it was only recently that this interest was expanded to marine vertebrates as well as invertebrates. Since teleosts represent a different evolutionary path from that of tetrapods, observing the presence of emotions in fish would certainly allow scientists to understand the biological mechanisms behind emotions in a much broader context. A scientific study that was published in Scientific Reports on October 13 2017, showed that Sea Breams' responses to external stimuli vary depending on whether the spur was presented in a predictable or an unpredictable way, thus suggesting that fish exhibit human-like emotions that are triggered by their reactions to external incentives.

In recent years, the general scientific consensus has significantly shifted towards adopting the idea that animals should - at least theoretically - be able to express human-like emotional states that are regulated by their perception of the environment. However, quantifying those emotions in an objective experimental way is no easy task. Nevertheless, the appearance of emotional responses in animals likely emerged as an evolutionary way to enhance their assessment of their surroundings, which would ultimately increase their chances of escaping predators (i.e., avoiding threats), as well as finding food and mates (i.e., identifying potential rewards). Furthermore, a recent study entitled "Gibson, W. T. et al. Behavioral responses to a repetitive visual threat stimulus express a persistent state of defensive arousal in Drosophila" demonstrated the existence of primitive internal emotional states in fruit flies.

To examine the fish's response to a predictable external stimulus, Sea Breams were trained to recognize a predictable favorable or aversive emotional trigger as such. After that, scientists exposed them to a predictable/unpredictable favorable or appetitive stimuli. The results showed that, contrary to what was previously held, fish's reactions varied greatly depending on the nature of the stimulus. Positive stimulus increased social interactions between the fish, while negative stimulus made them more likely to carry escape attempts. Moreover, the researchers observed that the responses were more frequent in fish exposed to predictable stimuli than those who were tested in an unpredictable setup.