Fish – yes fish – can distinguish one human face from another

Researchers have found the archerfish is able to recognize human faces

The old myth about goldfish having a three-second memory has already been thoroughly busted, but now researchers have provided more evidence of fish's recall abilities. They have discovered a species of tropical fish can distinguish one human face from another, which is something believed to require a more sophisticated brain than many animals, including fish, are thought to possess.

Conducted by scientists from the University of Oxford in the UK and the University of Queensland in Australia, the research focused on archerfish, a tropical species that spits jets of water to knock flying insects out of the air. The fish were first trained to spit at a picture of a particular human face on a monitor above the tank. Then, that face was shuffled in amongst 44 new ones, and the fish were able to pick out the original face with a surprising degree of accuracy.

"In all cases, the fish continued to spit at the face they had been trained to recognize, proving that they were capable of telling the two apart," says Dr. Cait Newport, the first author of the study. "Even when we did this with faces that were potentially more difficult because they were in black and white and the head shape was standardized, the fish were still capable of finding the face they were trained to recognize."

At their peak, the fish were able to identify the correct face 81 percent of the time in the first experiment, and 86 percent in the second, where more obvious differences were removed from the images, such as color, brightness and head shape.

You might not find it too hard to recognize people you know, but the researchers say that differentiating between human faces is a more complicated task than it seems. Evidence suggests that a region of the neocortex in the human brain is dedicated to facial recognition and, so far, that ability has only been demonstrated in other animals that possess a neocortex, like dogs, horses, sheep, cows and birds.

The fact that fish are able to join the list, despite lacking a neocortex, suggests that creatures with simpler brains may be capable of more complex thought processes than currently thought and that recognizing human faces doesn't necessarily require complicated brains.

The study was published in the journal Scientific Reports, and the marksmanship of the archerfish can be seen in action in the video below.

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