The traditional notion that only humans can think abstractly has been steadily chipped away by research on other animals. A new study credits an invertebrate for the first time with such a sophisticated skill: Honeybees can conceptualize "sameness" and "difference." Researchers say honeybees may serve as a good model system for determining how nervous systems learn concepts.
Earlier research on vertebrates such as pigeons and dolphins has suggested they can recognize sameness and difference, among other concepts. Invertebrates have been largely ignored when it comes to complex cognition, although some recent studies have shown that honeybees can recognize and memorize patterns. Following up, a team led by neurobiologist Martin Giurfa of the Free University of Berlin in Germany investigated the ability of bees to make decisions based on abstract concepts.
Giurfa and his colleagues first trained bees to associate certain stimuli with a food reward. In one experiment, for instance, bees saw a blue patch at the entrance to a Y-shaped tube. Once inside, they could choose between heading down the arm with a blue target at the end or the arm that ended in a yellow target. They learned to go to blue, where sugar was hidden.
Next, the researchers tested whether the bees could use what they'd learned in a new situation. When the colors were replaced with patterns of vertical bars and horizontal bars, most bees promptly headed toward the pattern identical to the one at the entrance. This indicates they had formed a concept of "sameness" that they applied to the novel situation. Conversely, bees trained to head toward different colors headed toward differently barred patterns. The bees could even apply their new knowledge to other senses: Those trained on the smells of lemon and mango successfully transferred what they learned to the colors blue and yellow, the team reports in the 19 April issue of Nature.
The results are "novel, clever, [and] extremely elegant," says cognitive ecologist Reuven Dukas of Simon Fraser University in British Columbia. In the future, the researchers hope to pinpoint the neuronal basis for such abilities. Because honeybees have less than 1 million neurons, Giurfa says, "you have a combination of extremely rich behavior and a simple nervous system that you can study."