The idea that culture is uniquely human has been swept away by recent discoveries about many animals, including whales, meerkats, orangutans, and birds. But until now, there has been little empirical evidence that social transmission and copying occur in less cognitively advanced species.

Sabine’s lab experiments show that fruitflies (Drosophila melanogaster) perform mate-copying, in which females learn sexual preferences from watching others mate. Does this behavior constitute culture? To answer this, Sabine and her co-researchers at TULIP required a transferable definition. “The typical criterion of culture is generally that transferred traits must be socially acquired and spread to others repeatedly,” they write. “We propose a definition focusing on the properties of social learning.”

The researchers set up five rules to test whether mating behavior was socially learned across age classes, memorized for sufficient time to be copied, trait-based, and conformist. Given these demanding criteria, Sabine’s team was delighted to see their flies produce a five-star performance.

After watching others mate with green or pink males, female flies preferentially mated with males of the color preferred by the female they had observed. This social learning occurred whether the observed flies were the same age or 11 days older (i.e. the age of parents). Colorbased copying continued even when the pink and green males had another contrasting trait such as curly wings or white eyes.

The socially learned sexual preferences were highly durable. After watching five demonstrations spaced by resting intervals, the flies continued to display unusually high mate-copying 24 hours later. Considering the flies’ short lifespan, this demonstrates long-term social memory. Using a new hexagon device to test six female observer flies at once, researchers also found that learned behaviors persisted for at least eight transmission steps.

Extract of the IAST Connect #14, Spring 2019

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