© Corbis
As human populations grow, our societies are behaving more and more like ant colonies.
The similarities offer a look at just how ever-growing human societies could collapse.

The human population is growing at such a staggering rate that we are organizing ourselves more like ant supercolonies, with new research finding that we have more in common now with some ants than we do with our closest living animal kingdom relatives.

The new study, published in the journal Behavioral Ecology, points out that both humans and ants (termites, too) live in societies that may consist of up to a million plus members.

"As a result, modern humans have more in common with some ants than we do with our closest relatives the chimpanzees," Mark Moffett, author of the study, told Discovery News. "With a maximum size of about 100, no chimpanzee group has to deal with issues of public health, infrastructure, distribution of goods and services, market economies, mass transit problems, assembly lines and complex teamwork, agriculture and animal domestication, warfare and slavery."

"Ants have developed behaviors addressing all of these problems," added Moffett, a research associate at the Smithsonian Institution's National Museum of Natural History. He pointed out that only humans and ants have developed full-blown warfare.

Moffett analyzed ant societies, and specifically those of the Argentine ant. This ant has colonies that expand hundreds of miles. One colony, with a total population probably in the trillions, spans over 621 miles from San Francisco to the Mexican border in California. An even larger colony exists in Europe, with supercolonies of Argentine ants also in Australia, New Zealand, and ever-widening regions of Hawaii and Japan.

What makes such size and growth possible for a society is that membership can be anonymous, Moffett determined. Members are not required to distinguish each other as individuals for a group to remain unified. Societies are instead bonded by shared identity cues. For ants, those are largely tied to pheromones.

Humans release pheromones too, but we bond in other unique ways.

Moffett explained that "societies require a nationalistic or patriotic kind of bonding, the sort that soldiers die for. The cues humans have used since prehistory to form these groups have included language, rituals and other ethnic traits, though a transformation in recent generations from mostly nationalist (ethnically homogenous) societies to multi-ethnic societies has required increasing dependence on abstract symbols."

Anonymous membership means that both human and ant societies can grow as large as environmental conditions allow, although some researchers suggest that an ultra large society can implode.

For example, David Queller and Joan Strassmann at Washington University in St. Louis predict that a society will collapse when individuals in the middle of a vast group of billions or trillions are no longer in contact with foreign societies of their species. They argue that this could allow for a gradual social decay. It would probably take centuries for this to occur, however.

One feature separating Argentine ant societies from human ones is that the ant colonies never appear to interbreed. This requires constant warfare on the borders of competing supercolonies. At those areas, foreign queens and males are killed. Each Argentine ant colony then takes its own evolutionary path, according to Moffett, acting like its own species.

Laurent Keller, an expert on Argentine ants who is in the University of Lausanne's Department of Ecology and Evolution, said that "overall, this makes sense."

Moffett, author of the book Adventures Among Ants, continues to study the populous social insects that are arguably among the most successful organisms on the planet.