Excerpt

Insect societies have intrigued natural historians and biologists since Aristotle. Scholars have puzzled over the self-sacrificing altruism expressed by sterile colony members—the workers—as well as the complex division of labor and the capability of mass-action responses to the environment. For example, a colony of twenty to thirty thousand honey bees, at one moment in time, may have several thousand individuals engaged in foraging behavior and thousands of others engaged in nest construction, feeding young larvae, or processing honey, while others guard the entrance or thermoregulate the nest. However, when an intruder challenges the entrance of the nest, hundreds or even thousands of worker honeybees may respond immediately by stinging the intruder and, in doing so, sacrifice their lives.

Social insects presented Darwin with major difficulties for his theory of evolution by natural selection. How can you explain the evolution of self-sacrificing worker castes when evolution is a result of the survival and reproduction of individuals? Even more perplexing is the question of how the sterile workers evolved their own traits, different from their reproductive mothers (the queens) when they don’t reproduce. But Darwin considered the “acme” of the difficulty to be the presence of distinct anatomical and behavioral castes as seen in many species of ants. How can nonreproductive individuals evolve such a complex caste structure?

The social behavior of insects is a result of complex interactions at different levels of biological organization. Genes give rise to proteins and peptides that build the nervous and muscular systems, regulate their own synthesis, interact with each other, and affect the behavior of individuals. Social behavior of an insect colony emerges from the complex interactions of individuals. The interactions that are the fabric of social organization are themselves far removed from the direct effects of the genes, thus providing a major challenge for understanding how insect societies evolve. Understanding how complex societies are organized and evolve is still a central question in evolutionary biology. We now know that, in order to understand how social organization evolves, we must understand the mechanisms that link the different levels of biological and social organization. We must determine the transformational algorithms that link gene to neural system, neural system to individual behavior, and individual behavior to social organization.

BACK TO Worlds Hidden in Plain Sight