Gorillas as Statisticians!
Having known more than a few statisticians in my day, this finding came as no surprise to me*:
Apes are intuitive statisticians.
Inductive learning and reasoning, as we use it both in everyday life and in science, is characterized by flexible inferences based on statistical information: inferences from populations to samples and vice versa. Many forms of such statistical reasoning have been found to develop late in human ontogeny, depending on formal education and language, and to be fragile even in adults. New revolutionary research, however, suggests that even preverbal human infants make use of intuitive statistics. Here, we conducted the first investigation of such intuitive statistical reasoning with non-human primates. In a series of 7 experiments, Bonobos, Chimpanzees, Gorillas and Orangutans drew flexible statistical inferences from populations to samples. These inferences, furthermore, were truly based on statistical information regarding the relative frequency distributions in a population, and not on absolute frequencies. Intuitive statistics in its most basic form is thus an evolutionarily more ancient rather than a uniquely human capacity.
The experiments involved presenting chimps, bonobos, gorillas, and orangutans with two buckets with different absolute and relative amounts of carrots and bananas. The experimenters drew one item from each bucket, and held them in separate hands without showing the item to the apes. The apes then had to pick one of the hands, and were given the item in the hand they chose. More often than not (70-80% of the time), they picked the hand drawn from the bucket with more of their preferred food than their non-preferred food, even when the absolute amount of the preferred food was smaller. For example, they were more likely to choose the hand drawn from a bucket with 20 of their preferred item and none of the other item than one with 100 of their preferred item and 200 of their non-preferred item, or in another experiment, a ratio of 4:1 preferred to non-preferred over a ratio of 1:4 (several additional experiments ruled out alternative explanations).
In short, with their knowledge of the population distribution (the frequencies of the different items within the buckets), the apes were able to make inferences about samples drawn from those populations (the items in the hand). So apes are basically as smart as social scientists. I’m looking forward to the follow-up study in which it is shown that orangutans predict market behavior as well as PhD economists.
*I kid, I kid. Statisticians are wonderful people, when they’re people.