Some species of fish are able to recognize and differentiate human faces, new research has revealed. This is the first time such an ability has been seen in these animals.
University of Oxford investigators, together with compatriots at the University of Queensland in Australia, found the talent present in members of tropical archerfish. These animals were able to notice and remember human faces with a great deal of detail, researchers noted.
This skill was once thought to be possible only for higher primates, including our own species. The challenge comes that human faces have many features which are more or less identical, requiring smaller details to be noted for recognition to occur.
"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. To test this idea, we wanted to determine if another animal with a smaller and simpler brain, and with no evolutionary need to recognize human faces, was still able to do so," Cait Newport, a zoologist at the University of Oxford, said.
Fish in the study were able to distinguish one of 44 new faces, and recognized single individuals from the group. This shows that the animals are able distinguish fine detail in the faces, despite a lack of a complex visual cortex in their brains. After learning a new face, the creatures were tested to see if they could select it from a group of 44 images. Looking at unaltered photos, the fish recognized their goal 81 percent of the time. When head shape and skin color were removed from the images, recognition rates rose to 86 percent.
Archerfish are known for their ability to shoot jets of water at targets in the air in order to capture food. The animals often capture their insect prey by knocking them off twigs, using these powerful streams of water.
This experiment shows that complex brains are not necessary in order to recognize faces. The same ability has been previously shown to be present in birds.
Study of archerfish and investigation of their ability to recognize and remember human faces are detailed in the journal Scientific Reports.