Fish learn likes humans, says study


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Fish don't look anything like humans, yet the way both learn are remarkably similar, according to a study published in a recent issue of the journal Behavioral Ecology.

Jeremy Kendal and coauthors have found that Nine-spined sticklebacks (Pungitius pungitius) are capable of utilizing a social learning strategy seen in humans known as a ~hill-climbing strategy. In their study, this involves comparing the behaviour of other sticklebacks with their own experience and making choices that lead to obtaining more food.

The authors collected about 270 sticklebacks from Melton Brook in Leicester, splitting the fish into three experimental groups and one control group. The fish in the experimental groups were subjected to two different learning experiences and two preference tests in a tank with a feeder at each end.

First, they were free to explore the feeder at each end during a number of training trials, where one feeder (the rich feeder) supplied worms at three times the rate of the other (the poor feeder) in seven of nine trials; in the remaining two trials, the rates at which worms were supplied to the rich and poor feeders were reversed.

The fish were then tested to see which feeder they preferred. In the second training trial, fish that had learned a preference for the rich feeder observed other fish feeding but this time the rate at which worms were supplied to both feeders varied, with the (previously) rich feeder giving even more, the same number as, or less worms than the one the fish previously got their food from. In the second test, the fish were again free to swim around and choose their feeder.

The authors found that about 75 per cent of fish were able to use public information efficiently, switching to a feeder they previously experienced first hand as poor if they observed other fish feeding from it as a rich feeder.

Conversely, the fish ignored this public information when the feeder they saw other fishes feeding from did not offer more food than from their experience with it.

The authors also found that the likelihood of the sticklebacks copying the behaviour of others increased when the public- versus personal-rich feeder payoff was higher.

This study implies that the sticklebacks are able to use a sophisticated social learning capability known as a ~hill-climbing strategy that has not been previously demonstrated in other animals.

According to Jeremy Kendal, ~Hill-climbing strategies are widely seen in human society whereby advances in technology are down to people choosing the best technique through social learning and improving on it, resulting in cumulative culture.

Lots of animals observe more experienced peers and that way gain foraging skills, develop food preferences, and learn how to evade predators. But it is not always a recipe for success to simply copy someone. Animals are often better off being selective about when and who they copy.

"These fish are obviously not at all closely related to humans, yet they have this human ability to only copy when the pay off is better than their own. You might expect this ability in animals who are closely related to humans. In the case of the nine-spined stickleback, they have most likely adapted to their local ecology.

For more information, see the paper: Kendal, JR, L Rendell, TW Pike, and KN Laland (2009) Nine-spined sticklebacks deploy a hill-climbing social learning strategy. Behavioral Ecology 20, pp. 238"244.