What Ants Tell Us About Labor

Humans, like ants, have specialized skills.

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By Marlene Cimons, National Science Foundation

We live in a world of specialists, where division of labor represents the pinnacle of a civilized society. In that respect, we are a lot like ants. 

“Humans and social insects—ants, termites, bees, wasps—are the only animals who do this,” said Anna Dornhaus, associate professor of ecology and evolutionary biology at the University of Arizona.  “They live in societies and each individual appears to specialize in a fairly specific job. Most animals don’t do this.”

Dornhaus is trying to understand the origins of their highly evolved system, since it so resembles that of humans, and whether the breakdown of jobs within societies is critical to their success. Ants and other social insects have a much more sophisticated level of organization than most other animals.  They live in their own colonies, with complex communication processes, division of labor, and within structures that can be thousands of times bigger than the size of the individual insects.

In the case of ants, their colonies are ruled by a single queen, sometimes several queens, and the rest of the ants, all females, serve either as workers or soldiers.

“We want to understand about the world—why we are what we are,” Dornhaus said. “Where do we come from? Why do we have this division of labor? Maybe if we find out what made the ants go in this direction, it will tell us what made us go in this direction.”

The research potentially has far-reaching implications that go beyond simply adding to the body of scientific knowledge about insects. Computer scientists and engineers are very interested in how social insects solve organizational problems, and are using the information to design algorithms for artificial problem-solving systems. The approach is called “insect inspired” algorithms.

“Working with ants is part of studying complex systems, that is, any system where you have multiple parts that are interacting, and they work without a central controller or hierarchal organization, “ Dornhaus said. “ Social insects offer a wealth of methods, optimized by evolution, of solving organizational problems in complex systems that consist of relatively simple parts. The problem solving happens in a distributed fashion, with multiple computers interacting to solve computational problems.

“However, I also think it shows that we should never underestimate an animal because it is small,” she added.

The National Science Foundation has provided $450,000 for the project, of which  $30,000 comes as part of the American Recovery and Reinvestment Act of 2009.

Specifically, Dornhaus and her colleagues are studying the turtle ant, of the species  Cephalotes rohweri, aptly named for its hard outer shell and tendency to pull in its legs and hunker down when threatened. Ants in the colony are all sisters, and genetically similar, but grow up with radically different body types, depending on the jobs they are destined to perform.

Soldier ants, for example, develop harder shells than their worker sisters, and have round, flat-shaped heads that look like big round plates and that they use to blockade the nest from enemies. “They put their heads in the entrance hole and no one can get past them,” Dornhaus said.

All the ants look the same at birth, but develop their specific body characteristics based on how much food the other ants provide.  “Not only does everybody have a specific job, but they are raised and made in body shape to conform to a particular job,” Dornhaus said. “From birth, they are geared to fulfilling this particular job.  They all look like maggots when they come out of the egg. Only when they are fed different amounts do they become a queen, or soldiers or workers. The workers care for the immature juvenile ants—the ones they feed a lot turn into queens.”

Males do little within this matriarchal society other than provide sperm. They don’t live in colonies once they become adults, nor,  in fact, do they live very long at all after that.  A young queen mates with a male or several males, and stores the sperm in her body for life. She then continues to produce eggs using sperm from her own tiny “sperm bank.”  Males born into the colony are nurtured until adulthood, when they leave in search of a young queen. Typically, they die not long after mating.