Harvard biologist Edward O. Wilson walks with focused wonder. He has spent 79 years exploring the insect world and has perfected the craft of spotting the tiny creatures. Ants are his specialty.
On a recent stroll through the woods at Rock Creek Park in Washington, D.C., he scans for favorable insect dwellings: decaying tree stumps and fallen logs. It's too cold to dig for ants today, so Wilson sticks to the path and fixes and his gaze 15 feet in front of him. He can spot anything that creeps and crawls within this perimeter.
Wilson recalls having roamed these woods with a homemade butterfly net when he was 9. He and his parents moved to the area from Alabama, where he had communed with snakes in swamps. In Washington, he found new creatures and spent much time at the National Zoo.
He recently paid another visit to the zoo to watch the resident colony of leafcutter ants. Wilson peers into one of the bustling ant tanks and says, "A colony like this one is the most complicated social system outside humanity."
The ants' social behavior has fascinated Wilson and fellow biologist Bert Holldobler for decades. In their new book, The Superorganism: The Beauty, Elegance, and Strangeness of Insect Societies, they devote an entire chapter to leafcutter ants.
Leafcutters are gardeners, growing white fungus farms on the leaves they harvest. It can take more than a million ants to support the queen, and every member of the colony has a job to do. Some harvest the leaves, some tend the "garden" and others protect it from invaders.
The ants have an extremely high division of labor. This is a trait shared by all superorganisms, which consist of many individuals working within a self-sustaining social unit. The leafcutter work force is all-female; males are born once a year, live short lives and function primarily as "a sperm-guided missile," Wilson explains. Some female leafcutters have the potential to reproduce, become a queen and start a new colony, but many do not. Workers who remain help care for the queen's eggs and offspring.
This altruism, part of what defines a superorganism, is what helps the colony survive.
Species that form superorganism colonies are highly successful. Yet Wilson estimates that only about two dozen of these highly social groups have been identified.
Wilson says this raises fundamental questions for biologists. "If social living is successful," he says, "why is it so rare? And why do groups arise in the first place?"