An experiment by researchers at the University of Oxford and the University of Queensland found that archerfish -- Toxotes chatareus, a species of tropical fish -- can recognize human face.
Treehugger.com pointed to the study, published in Scientific Reports, which disproved a long-held scientific consensus that facial recognition requires a large, high-functioning brain like those found in higher mammals, chimps and human beings.
"Being able to distinguish between a large number of human faces is a surprisingly difficult task, mainly due to the fact that all human faces share the same basic features," wrote the study's lead author Dr. Cait Newport, Marie Curie Research Fellow in the Department of Zoology at Oxford University. "All faces have two eyes above a nose and mouth, therefore to tell people apart we must be able to identify subtle differences in their features. If you consider the similarities in appearance between some family members, this task can be very difficult indeed."
It was previously believed that facial recognition as a brain function required a neocortex. Newport said, "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."
Archerfish are a tropical fish that hunts bugs and other small prey by shooting jets of water up through the air to strike plant stems and tree branches close to the water's surface. Scientists trained the fish to squirt water at a photo of a specific face when it was held over their tank.
Melissa Breyer at Treehugger wrote, "The fish were then given an array of new faces and were able to correctly aim their water jet at the face they had learned. They were able to do this among 44 new faces; and they were able to do this even when the head shapes were made the same and the color was removed from the photos."
"The fish were uncannily correct when picking the right face, reaching an average peak performance of 81 percent when selecting the known face from 44 others, and 86 percent when selecting the known face after the features were standardized," Breyer said.
Newport explained, "Fish have a simpler brain than humans and entirely lack the section of the brain that humans use for recognizing faces. Despite this, many fish demonstrate impressive visual behaviors and therefore make the perfect subjects to test whether simple brains can complete complicated tasks.”
