Research shows that fish can sense the fear of others

WASHINGTON (AP) — Our capacity to care for others may have very, very ancient origins, new research suggests.

The researchers, who published the study on Thursday Science magazine.

“Some of the mechanisms that underlie our ability to experience fear, or to love and be loved, are clearly very ancient pathways,” said Hans Hoffman, an evolutionary neuroscientist at the University of Texas at Austin, who was not involved in the study. .

Scientists are generally reluctant to attribute human feelings to animals. But it is generally accepted that many animals have moods, including fish.

A new study shows that fish can detect fear in other fish, and then be scared – and that this ability is regulated by oxytocin, the same brain chemical that underlies the ability to empathize in humans.

The researchers demonstrated this by deleting genes associated with the production and uptake of oxytocin in the brains of zebrafish, a small tropical fish often used for research. These fish were then inherently antisocial—they were unable to detect or change their behavior when other fish were anxious.

But when some of the modified fish received injections of oxytocin, their ability to reflect the feelings of other fish was restored – what scientists call “emotional contagion”.

“They respond to the fear of other individuals. In this respect, they behave just like us,” said University of Calgary neuroscientist Ibukun Akinrinade, co-author of the study.

The study also found that zebrafish will pay more attention to fish that have previously been stressed – a behavior the researchers compared to comforting them.

Previous studies have shown that oxytocin plays a similar role in fear transmission in mice.

The new study demonstrates a “frontier role” for oxytocin in the transmission of emotions, said Rui Oliveira, a behavioral biologist at the Gulbenkian Institute of Science in Portugal and co-author of the study.

This brain processing “may have already existed about 450 million years ago, when you and I and this little fish last shared a common ancestor,” Hoffman explained.

Oxytocin is sometimes thought of as the “love” hormone, but Hoffman said it’s actually more like a “thermostat that determines what’s socially salient in a particular situation — activating neural circuits that can lead to escape from danger or courtship behavior.” “

This could be fundamental to the survival of many animals, especially those that live in groups, said Stony Brook University ecologist Carl Safina, who was not involved in the study.

“The most basic form of empathy is contagious fear—it’s a very valuable thing to have to stay alive if someone in your group spots a predator or some other threat.”

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Follow Christina Larson on Twitter at @larsonchristina.

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