Fish Can Tell People Apart By Their Faces

An archerfish spits a jet of water. Cait Newport

The age-old myth about fish and their impossibly short memories may be somewhat wide of the mark, as new research reveals that some species are in fact capable of both recognizing and remembering human faces. What’s particularly remarkable about this discovery is that fish lack the complex brain structures that are responsible for facial recognition in more intelligent animals.

Humans and other primates, for example, have evolved specialized “maps” in a part of the brain called the neocortex that helps us to “read” other people’s faces. Fish, however, lack a neocortex altogether, which should make recognizing people’s mugs more or less impossible.

Yet as they stare out at us through their glassy eyes, it seems some types of fish may indeed be capable of distinguishing between us land-walkers.

Publishing a study in the journal Scientific Reports, researchers from the UK and Australia describe how they presented archerfish – which are famous for their ability to spit jets of water at insects above the surface – with pictures of two human faces. When the fish fired a jet at one of these faces, they received a tasty treat, and it wasn’t long before they learned which was the “correct” face.

To test the fish’s facial recognition ability, the researchers ran an experiment in which this face was presenting alongside 44 other faces. Amazingly, the fish were able to pick out the right face with incredible success, which ranged from 77 to 89 percent depending on the fish.


Archerfish being trained to recognize a face. Cait Newport/Motherboard

To make things a little harder, the researchers then adjusted the color and brightness of each photo to make them all the same, yet the clever fish were still able to recognize the correct face.

Commenting on this finding, the authors explain that “while it is impossible to say from our study whether archerfish use the same visual information to discriminate the face images as humans, our results clearly show that some aspects of the facial recognition task can be learned, even in the absence of a neocortex.”

They go on to suggest that the fish possess certain brain circuits that allow for “sophisticated discrimination” between external objects. This, they say, is probably crucial for their survival, enabling them to identify food, predators, and mates.

While it’s not necessary for fishermen to start wearing masks in order to avoid being recognized by their underwater targets, the research does have some implications for humans. For instance, it furthers our understanding of how we evolved into such brainy creatures, as the study point out that “it seems possible that pre-existing circuits for sophisticated visual discrimination evolved into the dedicated face-processing circuitry of primates.”


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