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HUMANS rightly regard the invention of agriculture about 10,000 years ago as one of the crowning achievements of our species. The ants beat us to it by at least 50 million years, however, with their cultivated fungus gardens. Ants are no dummies when it comes to decision-making, either, responding to environmental conditions and building intricate nests with a sophistication that seems uncanny for such tiny, small-brained creatures.

No single ant would ever beat a toad, let alone a human, in a test of wits, of course. The ants’ true genius comes from the “distributed intelligence” that emerges from vast numbers of simple components working in concert. Each ant is just a cog in a larger unit, like a neuron in your brain: only the larger unit – the superorganism – shows the hallmarks of intelligence.

“Each ant is just a cog in a larger unit, like a neuron in your brain”

tells the story of social insects and the way their remarkable colonies function as an evolved, adapted whole. True sociality – colonies with a division of labour in which abundant sterile workers support a few reproductive members – is more common than you might think. It occurs in ants, bees, wasps, termites, a handful of aphids, thrips, one unusual beetle, several other invertebrates and the naked mole rat.

So this book could have cut a wide swathe through the animal kingdom. As it is, honeybees figure prominently, since they have been so well studied, and once in a while a wasp or a primitively social bee crawls across the page to illustrate a point. However, and are ant geeks, so the vast majority of the book is overrun by ants.

At this point some readers will be thinking, wait a minute, didn’t they already write this book? Yes, sort of. In 1990, Hölldobler and Wilson wrote – a massive volume that went on to win a Pulitzer prize. But in the 18 years since, scientists have learned enough about sociality in ants and insects to warrant another book of similar heft.

In the new book, Hölldobler and Wilson dig deeply into the essence of sociality. Example by painstaking example, they lay out the interactions through which ants determine caste and decide which individuals will perform which tasks. At the simplest level, the instinct to move on to another task when the first is completed automatically leads to a division of labour. For example, harvester ant workers who vigorously perform one task channel other workers into other tasks. In more advanced ant societies, a worker’s role may be determined by a mix of hormonal signals, experience, genetic predisposition, current needs and pure chance. Summed across all of the colony’s workers, the effect is a remarkably optimal allocation of labour.

This emergent complexity is well illustrated by Hölldobler and Wilson’s comparative approach. Beginning with the rudimentary sociality of primitive ants, they trace the development of social organisation right through to the crowning glory of anthood: Attine leafcutter ants. The authors dedicate a chapter to these ants and their remarkable agricultural symbiosis with the fungi they cultivate in their underground gardens, as well as the intricate division of labour that makes it possible. We learn how the ants choose what vegetation to harvest, how they organise labour details to carry leaf matter back to their gardens, how they learn which foods make their fungus crop grow best, and how they keep their nest clean by removing spent vegetation after the fungus is done with it.

The mountain of footnotes alone make this book the perfect reference for any student or professional eager to grapple with the body of research on social insects. Occasionally the book descends into a nearly impenetrable thicket of jargon that only a specialist can navigate. But lay readers with an appetite for detail will find that most of the book speaks to them, too, thanks to the usually graceful prose of the Pulitzer prize-winning duo. Those with the stamina to make it through will gain a rare prize: a deeper understanding of a whole new level of biological organisation. Could human society, too, be regarded as a superorganism? Hölldobler and Wilson steer clear of that controversy, preferring to stick with the facts – and the ants.