You might not think you have much in common with the small, six-legged creatures that occasionally break into your home to raid jam jars, but over the next three articles I hope to illuminate some of the parallels between people and ants. Like humans, ants are highly social; building civilisations, utilising sophisticated mechanisms of communication, and nurturing other living creatures in various forms of agriculture. And just like us, their societies are sometimes compromised by cheats and criminals. Ants share many of these traits with other members of the social hymenoptera, which includes most bees and wasps. Few species outside this group have developed cooperation as sophisticated or complex.

There are over 15,000 species of ant worldwide, and they have all found slightly different solutions to the problem called life. One thing they all have in common, however, is group living. Even the most primitive species of ants cannot survive for long outside their home nest, and the most advanced species have developed societies millions strong, with complex systems for dividing labour amongst its occupants.

The army ants, for example, form enormous nests, sometimes housing as many as 700,000 adults, with a complex morphological caste system, in which workers are physically adapted to the role they play. The soldier caste is probably the most famous of these, with soldiers up to 3 times the size of their nestmates. The soldiers are not only large but also well armoured and carry large build-in weapons. Smaller army ants are divided amongst two important colony tasks; gathering food and raising young, while the queen specialises only in egg laying. Complex caste systems such as these come with huge benefits; each caste is a master of his trade, allowing the colony as a whole to be the master of all.

Just like humans, ants make a huge mark on their surroundings. Their skyscrapers usually extend below group rather than above it, but are designed with far more sophistication than anything we are able to build. Ant nests are capable of thermoregulating themselves to provide ideal conditions year-round. However, not all ants build their nests this way, and some species survive in seemingly uninhabitable environments. One species of ant is so tiny it makes a home in rock crevices, often only a few millimeters wide.

Collectively, ant colonies display surprisingly high levels of intelligence. Although dispersed amongst many bodies, some ant colonies contain more neurons than the human brain. However, the mechanism behind their intelligence is relatively simple, and is an example of emergent intelligence, in which intelligent behaviour arises out of a simple set of rules. The key to this is communication between workers, which they achieve using pheromones. This system may superficially appear simple, but ants and other social insects are able to utilise it to achieve highly complex communication. Around 40 different pheromone glands have been discovered in ants, and there are over 1000 chemical compounds involved. Pheromones, combined with some visual communication, produce sufficient diversity to achieve highly sophisticated interactions.

In contrast to many human societies, ant civilisation is far from democratic. Instead they use a system based on a royal matriarchy. Nests are ruled by one or a few queen(s) who is mother to all her subjects. It is this that may be the key to their success; high relatedness within colonies means that by helping your nestmates, you help relatives. High-relatedness is one thing ants have that we do not. However, during early human evolution, when population size was much lower, relatedness between groups of regularly-interacting people may have been higher. This would have greatly increased the benefits associated with cooperative behaviour, and may go someway to illuminating the extreme acts of selflessness occasionally observed between unrelated humans today.

Across the 15,000 or so species of ant, colonial life varies greatly, from the simple to the advanced, from species which nest in the gaps between rocks to those who forge intricate homes deep below ground, those that are little more than the kids sticking around to help mum, to species with workers who display dramatic physical adaptations to their role. The ants have found a multitude of ways to make a living, but the one thing that they all have in common; society, has lead to the development of sophisticated communication systems, complex politics and collective intelligence to rival that of humans.

Articles in this Series:

Part One: Civilisation
Part Two: Agriculture – Crops and Livestock
Part Three: Crime and Punishment

Want to Know More

• Army Ants: Inside the Ranks National Geographic
• BBC Nature Wildlife: Army Ants
• Ants Colony and Multi-Agents
• Of Ants and Men
• Collective Intelligence in Ant Colonies The Fountain Magazine
• Wyatt TD (2010)Pheromones and signature mixtures: defining species-wide signals and variable cues for identity in both invertebrates and vertebrates J Comparative Physiology A-Sensory Neural and Behavioral Physiology