The Superorganism: The Beauty, Elegance, and Strangeness of Insect Societies

In the tradition of their monumental 1990 work, The Ants, this new contribution from Holldobler and Wilson is a hefty, substantial and intellectually challenging book. It brings readers up to date on the large amount of research on ants that has happened since. Other eusocial insects are given mention but the focus is ants, to which each of these scientists have devoted large portions of their careers. It is not light reading, but if insects, evolution, communication, and/or biology interest you, then you'll find plenty here to engage you. In addition to some 500 pages of text there are many beautiful color plates and black-and-white illustrations. You will learn some pretty amazing things about ants. For instance, African stink ants memorize forest canopy patterns overhead and reverse the image to find their way home. I was also stunned to learn that ants colonized land tens of millions of years before plants did, and would have liked the authors to have explained what those poor pioneers ate. A whole chapter is dedicated to the most complexly social of ants, the leaf-cutters. I watched a large colony of these ants carrying leaf fragments from a tree during a visit to Mexico last year, and wondered why smaller worker ants rode on leaves being carried by larger workers. The Superorganism provides one possible explanation. The hitch-hikers apparently protect the carrier ants from parasitic Phorid flies, which try to steal into the nest and pilfer from their fungal gardens or wreak some other unmentioned havoc. I witnessed another curious thing in Mexico: carriers occasionally lugged their green baggage in the wrong direction. The authors provide no explanation for this, though they do refer to carriers trundling smaller workers and brood "perhaps perversely" in the reverse direction to an old nest during emigration to new quarters. Only about 100 of the 10,000 known species of ants have been studied closely so far, and they will continue to yield surprises for as long as humans study them. Holldobler and Wilson will have left a solid foundation to build on.

This book tells of the growth of knowledge concerning social insects over the past two decades. Super-organisms are colonies of individuals knit by cooperation, communication, and division of labor. Social insects - ants, bees, wasps, and termites - make up about 2/3 of insect biomass, but only 2% of the species. In a tropical rain forest, ants alone collectively weigh more than all the mammals and land vertebrates. At maturity, each colony contains from 10-20 million members, according to species. In the great majority of instances, the colony members are all female. More than 905 of communications are chemical. Social insects distinguish their own nestmates from other colonies by using receptors on their antennae. Particularly interesting is the authors' focus on leafcutter ants, who about 50-60 million years before man evolved from a hunter-gatherer lifestyle to an agricultural life. Multiply inseminated queens (the rule) create markedly lower disease susceptibility for a colony. In-breeding is kept down by the fact that different colonies breed at about the same time. After the mating flight, all males die. Mortality is also very high for the young queens - well over 98%. The new queen digs the beginnings of a nest, and cultivates the fungus garden she started herself at first with a piece of her "home" garden. At first she consumes 90% of the eggs she lays. Similarly, the first hatching larvae are also fed eggs. If the fungus started by the queen fails, the colony is doomed. After a week or so the young workers open the nest entrance, and start foraging. The ultimate colony size may reach 5-8 million after 5 years. Younger workers tend to perform tasks within the nest. Vibratory sounds communicate to others nearby the quality of leaves being worked on. A queen lives over ten years; each year, thousands of females grow up to potential queens, and several thousand short-lived males develop from unfertilized eggs. Overall, the queen lays about 20 eggs/minute (28,800/day, 10.5 million/year). Fungus-growing ants fertilize the fungal garden with their own feces. Waste management is mainly performed by older workers destined to die soon anyway; those exposed to waste material die at a higher rate. A typical 6-year-old nest examined by experts contained 1,920 chambers, with 238 occupied by fungus gardens. The loose soil brought out weighted about 40 tons. The authors then go on to also cover nest migration in the more nomadic species and the instance when disease among their fungus gardens has become a problem.

Eighteen years ago, Hölldobler and Wilson won the Pulitzer Prize for General Non-Fiction for their book "The Ants." That book was an exhaustive study of the ant, yet written in an inviting enough way to gain popular readers. This new book expands past, but still includes, ants, and looks further into insect societies, including bees, wasps, and termites. Bringing in new research from the last two decades, "The Superorganism" explores the insect groups, bound together by complex communication, division of labor and altruism. By looking at insect societies less as a collection of individuals, and more as a part of a whole, our view of them, and of ourselves changes. Is a honey bee simply a mindless drone, existing only to support the queen, or a cell in a hive organism? This highly detailed, highly scientific and well illustrated book brings to light, and life, a much more complex insect world than most of us have ever considered.

This beautiful volume shows the amazing amount that naturalists have learned about eusocial insect species since the publication of the authors' Pulitzer Prize winning volume, The Ants, in 1990. The book is accessible to the lay reader, except for some introductory chapters that require some knowledge of genetics and population biology. These chapters can simply be skipped without compromising the understanding of other chapters. Both because of its breadth and the huge number of references to the professional literature, this book will likely become a reference for many researchers in sociobiology, including those whose specialty is eusocial insects. From a theoretical standpoint, this book champions two ideas that E. O. Wilson has vigorously supported despite considerable criticism by biologists and social theorists. The first is that all social species share many traits in common, so that there is room for a special field, which Wilson calls "sociobiology," that charts the commonalities and differences among social species. This notion, laid out in Wilson's brilliant 1975 volume by that name, was greeted with scorn and contumely by social theorists who vehemently objected to including human sociality as a mere variant of biological sociality. The ensuing debate is brilliantly documented in Ullica Segerstrale, Defenders of the Truth: The Sociobiology Debate (Oxford University Press, 2001). Of course, sociobiology has withstood the criticism of the ignorant and the intolerant, and is now a fully flourishing field. More recently, E. O. Wilson has become an ardent supporter of group selection, which holds that Darwinian selection occurs on multiple levels, including the gene, the individual, and in species with a high level of sociality, on the level of the group itself. The central theme of this volume is that the eusocial insects are the product of biological selection on the level of the insect society (bee hive, termite mound, ant hill). Until recently biologists have considered this concept anathema, and many still choke on the idea of selection above the level of the gene, as forcefully expounded by Richard Dawkins in The Selfish Gene (Oxford: 1976). Lately he has teamed up with a long-time proponent of group selection, David Sloan Wilson, to produce a coherent defense of the notion, in the context of insect sociality. The chapter devoted to this issue in the book is a masterpiece that explains clearly the compatibility of gene-level and societal-level selection, and avoids all of the errors commonly committed by group selectionists of a previous generation. This volume is a true tour-de-force, ably fulfilling two often incompatible goals, that of elegance, excitement and instruction for the general reader on the one hand, and a contribution on the level of basic research on the other.