Fish generally aren’t presumed to be particularly intelligent creatures, but at least one species of tropical fish–the archerfish–has been found to have an impressive capacity to recognize a familiar human face from 44 others. And the way the archerfish signifies a familiar face? By spitting at it.
The ability to distinguish between one human face and another is a somewhat complex process. The vast majority of humans share the same basic features: two eyes, a nose, and a mouth. Primates, for their part, have an advanced visual cortex that enables them to distinguish between monkey-friend and monkey-foe.
And scientists have long hypothesized that smaller creatures with smaller brains lack this recognition capacity.
Smaller-brained creatures such as fish. Which is why a team of scientists from the Universites of Oxford, UK, and Queensland, AU, took it upon themselves to ‘train’ archerfish in a lab to see if they could recognize a face.
Archerfish are a species of tropical freshwater fish that spit a jet of water from their mouth to knock down insects in branches above the water. We positioned a computer monitor that showed images of human faces above the aquariums and trained them to spit at a particular face. Once the fish had learned to recognize a face, we then showed them the same face, as well as a series of new ones.
That’s right, they trained the archerfish to spit at an image of specific human face (no word as to whose face that was). But what they found when they began to show new faces alongside the familiar one is particularly curious:
The fish were highly accurate when selecting the correct face, reaching an average peak performance of 81% in the first experiment (picking the previously learned face from 44 new faces) and 86% in second experiment (in which facial features such as brightness and colour were standardized).
Percentages which aren’t too bad by human standards, let alone by the standards of a tropical fish with absolutely no evolutionary need whatsoever to distinguish between human faces.
Alas, what this tells us is not so much that fish are especially intelligent, but rather that we can’t be too smug about our own capacity for recognition. As Newport said:
‘The fact that archerfish can learn this task suggests that complicated brains are not necessarily needed to recognize human faces.