Biological Sciences

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Scientific study shows fish make great multi-taskers

21st July 2004

First came news that fish feel pain, then research showed they’re smarter than you might think …. now a new study shows they’re good at multi-tasking too. University of Edinburgh biologists have found that when fish are vulnerable to attack, they become more adept at concentrating on tasks simultaneously. Experiments with a species of fish similar to guppies have shown that fish from high-risk environments identified predators with their left eyes and shoal mates with their right eyes. The research is significant because it appears to explain why humans have developed the ability to use different sides of the brain for specific tasks. The findings, which succeed earlier Edinburgh research on fish pain and intelligence, are published online today (21 July) in the Royal Society journal, Biology Letters.

Although it is well established that fish show signs of left and right “handedness”, biologists have never been able to state categorically why that is the case. The new Edinburgh study shows that the greater the risk from predators, the more likely fish are to display 'lateralisation' traits – in other words, using different sides of the brain for different tasks. Fish that swim in more dangerous waters have highly 'lateralised' brains while those from relatively safe environments display no tendency to use different eyes for different tasks. The threat posed by predators therefore appears to have been the driving factor in the evolution of lateralisation in fishes.

Dr Culum Brown, of the University of Edinburgh’s Institute of Evolutionary Biology, said: “Our study suggests that lateralisation allows fish to concentrate on shoal mates and predators simultaneously. Put another way, you could say that fish are very good at multi-tasking. In fish, all information received by the left eye is transmitted to the right side of the brain, and vice versa. Lateralisation is rather like having two computers to process information in different parts of the brain simultaneously, rather than just one.

“In humans, however, information from each eye goes to both sides of the brain – we have binocular vision as opposed to the monocular vision that we encounter in fish. On the face of it, there is no need for us to have lateralised brains. At some point in our evolutionary past, a change has taken place, nevertheless the fact that we retained a lateralised brain suggests that it must convey great advantages. The two hemispheres of our brain are a gift from the past and reminder of our evolutionary history.”