Ants

King Solomon saw ants as models of wisdom; the Dogon people of west Africa believe they were the mothers of the first humans; they attained movie-star status in the 1998 films “Antz” and “A Bug’s Life”.

Laurent Keller, a professor of ecology at the University of Lausanne, and Elisabeth Gordon, shed light on how these extraordinarily complex creatures operate and what we can learn from them.

Over the past 150m years ants have evolved into around 13,000 species: 772 in America, 50 in Britain and 1,250 in Australia.

Myrmecologists (ant specialists) are certain that thousands more are yet to be discovered.

From tiny leptanilline ants that look like a dusting of pepper to Australia’s 5cm (2-inch) bulldog ants, the weight of the Formicidae family is equal to that of the world’s population of humans and accounts for 10% of the biomass of all the creatures on the planet.

The global ant population is estimated at 10,000 trillion, greatly outnumbering any other sort of animal.

And the density of ant colonies can be astronomical: a “super-colony” of redwood ants discovered in the 1970s on the coast of the Japanese island of Hokkaido had more than 300m worker ants, over 1m queens and covered an area of 2.5 square kilometres.
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Mr Keller and Ms Gordon explain that the success of ants as a species lies in their sophisticated, strictly hierarchical social organisations.

Ant colonies are founded on two main “castes” of ant: queens, whose sole function is reproduction, and their industrious, sterile, worker daughters. (The only use for males is to inseminate the queen; afterwards they are either driven out of the nest or killed.)

Colonies operate through organised co-operation and task-sharing.

Ants work together to capture prey that is bigger than they are; they can call up extra workers when an abundant food source is discovered; they can defend a colony by repelling invaders.

Weaver ants use silk squeezed from ant larvae to “glue” leaves together for nest building. Nursemaid ants look after eggs, larvae and pupae, moving them from place to place each day depending on the temperature.

Ants of Switzerland’s Jura region search out antibacterial spruce resin and distribute it within their nests to reduce the number of pathogens.

The secret behind such organised societies is communication through the use of around 20 pheromones, emitted by ants’ secretory organs.

These chemical signals are used, among other things, by queens to attract males; for marking territory; to alert nest-mates to danger; to lead other ants to a source of food; and to tell them which ants are dying and need removing from the colony.

This pheromone-driven behaviour means that although single ants are not clever, collectively they are capable of complex tasks.

Such “swarm intelligence” is of huge interest to scientists and has already led to practical applications.

Unilever, for instance, has used a computer program based on swarm intelligence to organise movements between storage tanks, mixers and packing lines in one of its factories.

The Economist