Charles Darwin seemed to think so. In his last book published in 1881, he studied the habits and power of earthworms. Worms have no ears, but are sensitive to “vibrations conducted through the Earth.” This is another way of saying that worms can detect the footsteps of animals or humans. These detected sensations are then transmitted to collections of nerve cells in the worm’s head which Darwin calls “cerebral ganglia.” Although worms cannot hear, they can detect lightness and darkness. This is why during the day worms stay mostly underground where they are presumed to be safe from predators—predators they sense via vibrations which are transmitted to the cerebral ganglia.
“When a worm is suddenly illuminated,” Darwin wrote, it “dashes like a rabbit into its burrow.” At first Darwin believe this to be a reflex. However, he observed that if the worms were engaged in other activities they would not withdraw into soil from sudden exposure to light. Darwin believes that this ability to perform different responses to the same stimuli indicates “the presence of a mind of some kind.” Darwin argues that if humans were faced with the same predicaments as worms—having a mouth, but lacking ears, limbs, and almost all sight—we would act in a similar manner. Does this make worms intelligent? Worms have survived for millions of years and enriched our soils despite their bodily circumstances. If these creatures do in fact possess a brain, they deserve thanks for all their hard work.