BENGALURU: Scientists studying animal behaviour in groups are often found discarding the "noise" (statistical deviations from expected patterns) assuming it to be a nuisance that can be filtered out.
However, a new study on cichlid fish movement led by researchers at the Indian Institute of Science (IISc) upends this belief.
An IISc statement reads: "The study finds that noise can actually help us understand how complex group-level behaviours – such as swimming together in a synchronized manner to avoid predators and forage efficiently – emerge from simple individual behaviours."
It is very counter-intuitive, says Vishwesha Guttal, associate professor at the Centre for Ecological Sciences, IISc, and senior author of the paper published in Nature Physics. "We all usually think noise reduces order," he added.
Guttals former PhD student Jitesh Jhawar, the first author of the paper, and his colleagues closely tracked the cichlid fish Etroplus suratensis – a popular estuarine edible fish locally known as karimeen – swimming in large water tanks.
They studied both the direction in which the fish moved and the degree to which they were aligned towards each other. Crucially, the researchers also tracked how these behaviours fluctuated over time.
“What we find is that when the fish are moving in a misaligned state, the fluctuations are actually high,” says Danny Raj M, from the Department of Chemical Engineering, IISc, and a co-author on the paper.
And when fluctuations were high, it had surprising effects on the behaviour of the group: they became more synchronized in their swimming.
This was because each member of the group was copying the direction of one of its neighbours, chosen randomly; this is in contrast to classical models, which have suggested that each fish copied what the Read More – Source