There's a rude, spitting fish out there that can distinguish between human faces, and that's just great.
The archerfish are a strange family of fish that hunts their insect prey by spitting a stream of water, knocking them out of the air or off branches into the water where they can make a meal out of them.
And as a new study in the journal Scientific Reports has found, these fish are members of the select club that can tell the difference between specific human faces.
This is an impressive feat. Scientists used to believe this was only possible for animals with far more complex brains than the little spitting fish.
"It has been hypothesized that this task is so difficult that it can only be accomplished by primates, which have a large and complex brain," first author of the study, Cait Newport, a zoologist at Oxford University said in a press release. "The fact that the human brain has a specialized region used for recognizing human faces suggests that there may be something special about faces themselves."
In the study, researchers trained the fish to spit at a computer screen placed above their aquarium. After getting the fish to identify a specific human face displayed on the screen by rewarding them with food, they presented them with 44 new human faces.
The fish in the study were able to pick out (read: spit on) the specific face 81% of the time in the first experiment, and 86% of the time in the second experiment, once the researchers standardized facial color and brightness.
This ability to distinguish between our faces doesn't serve the archerfish any evolutionary purpose. (Let's face it, spitting at specific humans from the water is not going to make them live any longer or reproduce more.)
But it does suggest there's more to picking a face out of a crowd than a brain with high processing power or complex structures, like the neocortex inside human heads (and those of other primates). And while some birds, like pigeons and crows, can also differentiate between human faces, their brains are also believed to house structures similar to our neocortices.
"The fact that archerfish can learn this task suggests that complicated brains are not necessarily needed to recognize human faces," explained Newport.
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