Tropical archerfish can recognise faces according to Oxford University study

The research, carried out by a team of scientists from Oxford University and the University of Queensland in Australia, found that archerfish were able to learn and recognise faces with a high degree of accuracy.

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."

The researchers found that fish, which lack the sophisticated visual cortex of primates, are nevertheless capable of discriminating one face from up to 44 new faces.

In the study, archerfish – a species of tropical fish well known for its ability to spit jets of water to knock down aerial prey – were presented with two images of human faces and trained to choose one of them using their jets.

The fish were then presented with the face they had learned and a series of new faces and were able to correctly choose the face they had initially learned to recognise.

They were able to do this task even when more obvious features, such as head shape and colour, were removed from the images.

The fish were highly accurate when selecting the correct face, reaching an average peak performance of 81 per cent in the first experiment (picking the previously learned face from 44 new faces) and 86 per cent in the second experiment (in which facial features such as brightness and colour were standardised).

Dr Newport added: "Fish have a simpler brain than humans and entirely lack the section of the brain that humans use for recognising faces.

"Despite this, many fish demonstrate impressive visual behaviours and therefore make the perfect subjects to test whether simple brains can complete complicated tasks.

"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 recognise a face, we then showed them the same face, as well as a series of new ones.

"‘The fact that archerfish can learn this task suggests that complicated brains are not necessarily needed to recognize human faces."

The study is published in the journal Scientific Reports.