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Week of 12 November 1999 Vol. III, No. 14 Feature Article Evolutionary Wars Biologist's book takes reader to the front lines of nature's battles By Brian Fitzgerald When Charles Levy and his family walked near their home in Kenya, they learned to keep their eyes on the ground. The reason: army ants. "I remember having to pry open the jaws of a few that had latched onto my son," recalls the CAS biology professor, who, as a Fulbright scholar, was a professor at the University of East Africa in 1969 and 1970. But insect attacks in Nairobi also came from the bushes. Levy remembers rushing his four-year-old daughter to Nairobi Hospital after a bombardier beetle sprayed its venom in her face. "The attending physician told me she had Nairobi Eye, an inflammation caused by these insects' chemical weapons, which are squirted from a nozzle on the tips of their abdomens," says Levy with a cocked eyebrow. Even predatory grasshopper mice, which also feed on scorpions, scurry away from these arthropods. Bombardier beetles use an irritating, hot repellent spray to repulse enemies. Their marksmanship can even fend off grasshopper mice, which feed on scorpions. Illustration by Trudy Nicholson Levy, the author of Evolutionary Wars: A Three Billion Year Arms Race -- The Battle of Species on Land, at Sea, and in the Air (W. H. Freeman and Co., 1999), has always been interested in predator-prey relationships. "I believe that my fascination with life's struggle for survival began when my parents read me such stories as David and Goliath and Rudyard Kipling's The Jungle Book," says the 75-year-old. That was before television, when many parents did read to their children. Still, those raised during the television age -- and who are big fans of nature shows on the Discovery Channel and Animal Planet -- will appreciate the book because it manages to cover 4.5 billion years of history in 278 pages, and includes examples from every environment. Like the bombardier beetle repelling the grasshopper mouse (see illustration below), two-inch long dendrobatid frogs of Central and South America (they can be lethal to the touch), and black widow spiders, which kill creatures much larger than themselves, the Davids of the animal kingdom are sometimes able to slay the Goliaths -- or at least get away from them -- using a wide array of attack and defense methods. As a photo-safari guide in Kenya, Tanzania, and Uganda, Levy watched in fascination as lions hunted eland antelopes. "Three lionesses started moving on an eland that was 300 yards away," he recalls. "When they were 200 yards away, the eland's head popped up and its ears pricked up. Then it rose to its feet and stared at the lionesses. It was communicating to the predators, 'I see you, and if you charge, I'll outrun you. So the lionesses abandoned their hunt." In the book, he explains that this alarm system in vertebrate land animals is from an ancient evolutionary structure in the brain stem. The "call to battle stations" focuses the prey's attention on what is relative to its survival. In turn, the predator refuses to waste energy in futile pursuit. Charles Levy and some friends, Madagascar hissing cockroaches. The insects have small holes, or spiracles, on their back for breathing. When they feel threatened, they make hissing sounds similar to that of snakes. Photo by Randy Goodman "A pilot doesn't want his plane to run out gas when making a kill," says Levy. He should know: during World War II he earned both aerial gunner's wings and navigator's wings while serving in North Africa and Europe. Perhaps that is why he developed a fascination with the dogfight success of bats, which can in one night chalk up 3,000 insect kills. Or for that matter, swifts ("undeniably the ace of aces in the bird world"), which can fly 110 miles an hour, and enjoy 20,000 kills a day. In fact, no plane can take off backward, make an unbanked turn at full speed, and stop on a dime in flight like the dragonfly. "Dragonflies generate turbulence on the dorsal wing surface to enhance uplift," says Levy. "This action is something our modern aeronautical engineers can't duplicate." Military comparisons abound in the book. Indeed, the evolutionary selection pressures that pit predators against prey in an endless struggle are "analogous to an arms race, powered by competition," Levy writes. "The agenda for survival of both groups involves a variety of changes in the total weapon system, which includes not only the design of the hardware of actual weaponry but also the tactics and strategies that involve coevolution of both the hunters and the hunted." The Darwinian struggle for superiority and survival has produced some ingenious weapons in the natural world, including: Small fish of the genus Toxotes have developed a sort of submarine-launched ballistic missile: they spit droplets of water, stunning hovering insects. Didinium nautuum, which feeds exclusively on paramecia, have cannonlike structures called trichocysts, which release long, banded threads tipped with arrow-shaped barbs. Some moths are able to jam bats' sonar by emitting volleys of ultrasonic clicks. The electric ray, along with several other fish, can generate high-voltage electric pulses to immobilize prey. The pulses of the Amazon electric eel are intense enough to kill an adult human. Levy, whose office walls are festooned with human weapons and shields, including Masai war clubs, various axes, and blowguns from Central America, points out that many of the new strategies, tactics, and technologies involved in human conflict can be found in some of the most simple life-forms. "In the last chapter," he says, "I also tried to provide some insight into the paradox of the dark side of human behavior." After all, even the ruthlessness of the army ants isn't a conscious behavior. "Only humans have instruments of mass destruction," he says. "Only humans are capable of genocide and cruelty."