Post by Bozur on Nov 24, 2008 3:04:44 GMT -5
E Pluribus Unum
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By STEVE JONES
Published: November 21, 2008
Not long ago, I was stung by a metaphor. A gang of paper-wasps guarding their shared nest, irritated at my exposition of their habits to a bunch of students, went on the attack. The effects were unpleasant — a hot, sweaty, choking feeling and an overwhelming desire to take a cool shower (which did not help).
From “The Superorganism”
Leaf-cutter ants working cooperatively on a live twig.
THE SUPERORGANISM
The Beauty, Elegance, and Strangeness of Insect Societies
By Bert Hölldobler and Edward O. Wilson
Illustrated. 522 pp. W. W. Norton & Company. $55
Those who use such creatures as parables, as so many philosophers have done, face — metaphorically speaking — the same danger. Social insects have often been co-opted as models of human society. The right uses them to celebrate the power of hierarchy, the left that of community. Bees attract the liberal and optimistic (the spirit of the beehive), ants the conservative and the anything but (the city as ant heap). Lyndon Johnson found such creatures useful in his Inaugural Address: “I do not believe the Great Society is the ordered, changeless, and sterile battalion of the ants. It is the excitement of becoming, trying, probing, falling, resting and trying again,” but politicians of every flavor have turned to them for a series of useful, albeit contradictory, lessons from Nature.
This book, on the other hand, is just about wasps, bees, ants and termites. “Just” is not the mot juste, for in its 500-plus pages “The Superorganism” gives an astonishing account of the intricate and unexpected ways of the social insects. Its co-authors, Bert Hölldobler and E. O. Wilson, won a Pulitzer Prize in 1991 for their earlier book, “The Ants,” but the science involved (if not the use of ants as metaphors) has made enormous strides since then.
Hölldobler and Wilson’s central conceit is that a colony is a single animal raised to a higher level. Each insect is a cell, its castes are organs, its queens are its genitals, the wasps that stung me are an equivalent of an immune system. In the same way, the foragers are eyes and ears, and the colony’s rules of development determine its shape and size. The hive has no brain, but the iron laws of cooperation give the impression of planning. Teamwork pays; in a survey of one piece of Amazonian rain forest, social insects accounted for 80 percent of the total biomass, with ants alone weighing four times as much as all its mammals, birds, lizards, snakes and frogs put together. The world holds as much ant flesh as it does that of humans.
Karl von Frisch, discoverer of the famous waggle dance of the honey bee, said in the 1930s that “the life of bees is like a magic well. The more you draw from it, the more there is to draw.” Plenty of excellent science still springs from that source, and Wilson and Hölldobler gather some classics here. How does an ant work out how far it is back to the nest? Simple: by counting its steps. Glue stilts onto its legs as it sets out and it will pace out into the wilds; take them off and it will walk only part of the way back.
The superorganism has castes, based not on genetic differences but — like our own social classes — on the environment in which they are brought up. Sometimes, a chemical message does the job, but cold and starvation can be just as effective at condemning an individual to a humble life as a worker.
A few simple rules produce what appears to be intelligence, but is in fact entirely mindless. Individuals are automatons. An ant stumbles on a tasty item and brings a piece back to the nest, wandering as it does and leaving a trail of scent. A second ant tracks that pathway back to the source, making random swerves of its own. A third, a fourth, and so on do the same, until soon the busy creatures converge on the shortest possible route, marked by a highway of pheromones. This phenomenon has some useful applications for the social animals who study it. Computer scientists fill their machines with virtual ants and task them with finding their way through a maze, leaving a coded signal as they pass until the fastest route emerges. That same logic helps plan efficient phone networks and the best use of the gates at J.F.K. In the phone system each message leaves a digital “pheromone” as it passes through a node, and the fastest track soon emerges. Swarm intelligence does wondrous things.
Swarm sex is even more remarkable. Louis XII of France wore a surplice edged with golden bees and beehives emblazoned with the motto “Rex non utitur aculeo” (the king has no sting). He was right: the sting-less male’s only job is to inseminate females, who sting and sting again in defense of their nest. The queen herself packs a punch, although most of the time she is too busy to do much damage. Among the leaf-cutter ants, “Earth’s ultimate superorganisms,” with their uniquely intricate societies, a single queen may produce as many as 200 million female (and sterile) offspring in her lifespan of 10 to 15 years, together with a few males, whose only job is to replenish the sperm supply (not a job that Louis XII himself did particularly well).
Researchers used to believe such behavior turned on the skewed patterns of kinship of bees and ants, in which sisters are more related to each other than they are to their mother, thanks to a strange sex-determination system in which males have a single set of genes and females two. That in turn means that female infertility (and an associated willingness to help one’s mother produce more sisters) makes evolutionary sense. Unfortunately, many insects with that odd genetic pattern are solitary, while certain mammals with a more conventional sexual system, like the naked mole rat, also have a single dominant queen, a few favoured males and a cowed phalanx of workers who help her reproduce. Parental care alone, and an associated division of labor, may favour the evolution of such societies (although close relatedness does help).
The world of superorganisms varies from that of the relatively primitive “dawn ants” of Australia, which live in groups of a hundred or so separated only into sexual and asexual kinds, to the leaf-cutters, found only in the New World, who cultivate fungal gardens and have millions of workers, divided into a diversity of castes, in a single colony. The whole place buzzes with information, passed on with chemical cues, taps and strokes, dances and displays. Such “collective wisdom” is fatally open to mathematical modeling (and there is plenty of it out there), but as Hölldobler and Wilson say, natural history — experiment and observation — is what really counts.
There is no shortage of first-rate natural history here, and although some is expressed in technical language (ergatogynes, gamergates, nanitic workers), anyone interested in what real biology — the study of life, rather than of chemistry — is up to nowadays could do no better than read this volume.
Philosophers, however, might be better advised to avoid it. Alexander Pope was well aware of the dangers of six-legged metaphors: “Thus Ants, who for a Grain employ their Cares, / Think all the Business of the Earth is theirs. / Thus Honey-combs seem Palaces to Bees, / And Mites imagine all the World a Cheese.” Wilson in his earlier writings seemed to fall into that trap; to see evolution as a seamless transition from the primeval slime to the 21st century and to call in the ants (if not the mites) for evidence. “The Superorganism” is far more cautious: only in its last few paragraphs does it draw a parallel to ourselves — a once-rare species whose social skills and ability to cooperate have led, as with the bees and ants, to an extraordinary outburst of numbers. And it acknowledges that we, unlike them, are ruled by intelligence rather than mere instinct — intelligence that “has allowed us to control and destroy the global environment for short-term gain, the first time that was achieved by any species in the history of the planet.”
Charles Darwin would have been delighted by this book. His own literary oeuvre was aimed at a wide audience and set out in good, plain Victorian prose. As he wrote to Thomas Henry Huxley, “I sometimes think that general and popular Treatises are almost as important for the progress of science as original work.” A century and a half later, “The Superorganism” sits firmly in that distinguished tradition.
Steve Jones is professor of genetics at University College, London, and the author of “Darwin’s Ghost: ‘The Origin of Species’ Updated.”
www.nytimes.com/