A species of tropical fish has been shown to be able to distinguish between human faces, according to a new study.
It is believed that this is the first time fish have demonstrated this ability.
The research, carried out by a team of scientists from the University of Oxford (UK) and the University of Queensland (Australia), found that archerfish were able to learn and recognise faces with a high degree of accuracy – an impressive feat, given this task requires sophisticated visual recognition capabilities.
The study is published in the journal Scientific Reports.
First author Dr Cait Newport, Marie Curie research fellow in the Department of Zoology at Oxford University, said: “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.
“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 has been hypothesised that this task is so difficult that it can only be accomplished by primates, which have a large and complex brain. The fact that the human brain has a specialised region used for recognising 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 recognise human faces, was still able to do so.”
The researchers found that fish could tell the difference between one face from up to 44 new faces. The research provides evidence that fish have impressive visual discrimination abilities.
The fish were highly accurate when selecting the correct face, reaching an average peak performance of 81 percent in the first experiment (picking the previously learned face from 44 new faces) and 86 percent in the second experiment (in which facial features such as brightness and colour were standardised).
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