[Reading Science] Fish Also Have Empathy (Gonggam) Ability

Canada-Portugal Research Team Publishes Paper in Science
Oxytocin-Removed Zebrafish Show Rough Behavior Due to Lack of Empathy
Chemical Involved in Human Brain Empathy Identified
"Suggests Human Empathy Began Over 450 Million Years Ago"

A study has found that fish also possess the ability to empathize. This suggests that humans' capacity to sense the emotions of their peers and show mutual consideration has deep roots dating back to before the Paleozoic era, prior to the divergence of mammals and fish.

An international research team from Canada, Portugal, and other countries published these findings on the 22nd of last month (local time) in the international scientific journal Science.

Zebrafish. Stock photo.

The research team observed the brains of zebrafish, a type of tropical ornamental fish, after removing oxytocin or deleting the gene responsible for producing it. These genetically modified zebrafish began to exhibit aggressive behavior. Despite other fish disliking it, they failed to detect this and could not change or regulate their behavior accordingly.

Subsequently, when oxytocin was injected into some of these genetically modified zebrafish, they regained the ability to sense and respond to the emotions of other fish. Moreover, these zebrafish showed more attentive behavior toward peers that had previously been stressed by them, as if offering comfort.

These findings demonstrate that zebrafish can detect the fear of their peers and strongly avoid it, indicating they possess empathy. It was also confirmed that this ability is regulated by oxytocin, a chemical involved in empathy in the human brain. Previous studies have shown that oxytocin plays a role in transmitting fear among peers in the brains of mice.

Earlier, in 2019, a study by a team at Stanford University in the United States revealed that zebrafish have REM (rapid eye movement) and non-REM sleep capabilities similar to humans and birds. This challenged the prevailing theory that only birds and mammals evolved REM sleep. It suggested that human sleep abilities originated over 450 million years ago, before the common ancestor of fish and humans diverged.

Hans Hofmann, an evolutionary neuroscientist at the University of Texas who was not involved in the study, told the Associated Press, "Some mechanisms related to human emotional abilities, such as feeling fear or falling in love, clearly have very ancient origins." He explained, "(This study) suggests that the human brain's capacity for empathy may have begun more than 450 million years ago, before humans and fish diverged from a common ancestor."