Fish have the reasoning capacity of a 4- or 5-year-old child when it comes to figuring out who among their peers is “top dog,” new research shows. Stanford University scientists made the discovery—said to be the first demonstration that fish can use logical reasoning to figure out their social pecking order—by studying fights among small, highly territorial, spiny-finned fish called cichlids, common in freshwater in tropical Africa, including in Lake Tanganyika in central Africa.
Logan Grosenick, a graduate student in statistics, and his colleagues found that a sixth fish could infer or learn indirectly which were the 1st through 5th strongest simply by observing fights among them in adjacent, transparent tanks, rather than by directly fighting each fish itself or seeing each fish fight all four others.
This type of reasoning, called transitive inference (TI), is a developmental milestone for human children, showing up nonverbally as early as ages 4 and 5; it also has been reported in monkeys, rats and birds. It allows thinkers to reason that if A is bigger than B, and B is bigger than C, then A is also bigger than C.
Anthropomorphizing animals, or casting human intentions on them, is a mistake, Grosenick said, but it’s a philosophical matter as to whether the cichlids’ ability to infer rankings is the same as similar reasoning in humans. “They are making correct logical inferences on an abstract representation of their world, which would usually be called ‘reasoning’ in humans,” he said.
Biologist Russell D. Fernald, one of Grosenick’s colleagues on the study, said that fish thinking is very different from that of humans. “The capacity shown here is a necessary precondition for reasoning, but having this capacity does not mean these fish actually reason or do any other specific logical tasks,” he told LiveScience.
I’ve written before about fish and intelligence:
For the entire article, visit Live Science.
[Live Science: Fish capable of human-like logic]