Life support

Quick--name an important mammal of the African savanna. If you re like me, you probably thought of the lion, the cheetah, the hyena, or any of several other toothy carnivores. But supporting many of those impressive creatures is the herbivore known as the gnu--or, more formally, the wildebeest. So when Richard D. Estes approached us about contributing an article to Natural History ("Wildebeests of the Serengeti," page 28), we became as excited as crocodiles hiding in a wildebeest watering hole. Estes is perhaps the world's leading expert on the wildebeest, one of Africa's signature large mammals, and no one is better suited to bringing all of us up to date on the gnus from the Serengeti.

So important is the wildebeest to the ecological health of the African savanna that biologists label it a "keystone" species. And for their part, wildebeests have adapted marvelously well to their role as Africa's hot meal on the hoof. Vast herds of them remain constantly on the go. Some 80 percent of the females manage to give birth within just a few weeks, ensuring that though some of the calves will become hyena fodder, plenty of others will survive to reproduce another day. The calving strategy also keeps the food glut brief enough to prevent a permanent expansion of predators. Precocious "gnuborns" fit right into the herd's strategy of moving on: they struggle to their feet, on average, within seven minutes after birth, ready for the dusty trail.

From our perspective as creatures living at the bottom of the atmosphere, the high mountains seem one of the most inhospitable places on earth. The air is thin, the sunlight burns, the wind howls, and the weather is unpredictable. Most of us are amazed when we discover, say, a wildflower growing in a crevice on a steep boulder field above 12,000 feet. It's a natural response, but by now it ought to be recognized as a parochial one. "Extremophiles"--the very name reflects our provincialism--live everywhere: in the superheated water and hydrogen sulfide issuing from deep-sea vents, in caves isolated from sunlight for millions of years, between layers of sea ice floating in the Arctic Ocean.

Yet until recently, even professional biologists had fallen into the anthropocentric trap of assuming the alpine zone is a sparse and barren land. Writer Kevin Krajick and photographer Carsten Peter ("Living the High Life," page 44) endured pounding headaches and worse at 17,000 feet in order to accompany a biological expedition whose goal was to prove the reverse. And sure enough, the slopes of the high Andes turned out to be home to a surprising diversity of life. Expedition members made so many new discoveries that their simple, factual descriptions sounded, unintentionally, like comic repetition: "the world's highest frog," "the world's highest worm," "the world's highest clam," "the world's highest leech." In fact, the superlatives reflected a lack of prior scientific attention as much as the expedition's own good luck. Making new discoveries in the mountains is easy, explained the expedition's chief scientist, Stephan R.P. Halloy, "because we are looking here."

COPYRIGHT 2006 Natural History Magazine, Inc.
COPYRIGHT 2008 Gale, Cengage Learning