Unearthening Old Data: Darwin was Indeed Correct About Earthworm Behavior

Abstract

Charles Darwin is well known for his studies on the expression of emotions in animals and humans and as founding father of the concept of sexual selection. Yet it is commonly believed that the various arguments Darwin developed about behavior were usually illustrated only by anecdotes and observations recounted by explorers, naturalists, or zookeepers, and lacking any experimental approach. Here we show that this is not true. In his last book, The Formation of Vegetable Mould Through the Action of Worms (1881), Darwin mentions a series of meticulous experiments he ran to test his hypotheses about why earthworms plug their burrows and comes to the conclusion that earthworms seem to act in an intelligent way. His study can still function as a prime example of how to design an experiment for testing hypotheses. Only one part was missing in Darwin’s research: statistical analyses. We retrieved his data and analyzed them statistically. Based on these results, we cannot reject his conclusion as the statistical analyses confirmed Darwin was right. This shows that Charles Darwin already used a hypothetico-deductive approach, and he can thus be seen as the first true behavioral ecologist—a representative of a discipline that has been recognized for only about a hundred years.