Rain Forest Crunch; March 1996; Scientific American Magazine; by Schneider; 1 Page(s)

Going up that river was like travelling back to the earliest beginnings of the world, when vegetation rioted on the earth and the big trees were kings." Joseph Conrad's evocative portrayal of the Congo would seem to apply as well to the Amazon. That river travels across the South American continent from Peru to the Atlantic Ocean, cutting through nearly four million square kilometers of undisturbed woodlands. But is the Amazon rain forest truly a primeval jungle, a steamy, green mass that has endured for millions of years? Perhaps not, according to new results from the high Andes.

The current findings challenge a perception, which first emerged in the 1970s, that tropical climates remained virtually unchanged while the great ice sheets of North America and Europe waxed and waned through a series of Pleistocene ice ages. That view was based largely on a study of microscopic shells from the ocean floor. Analyses of the kinds of creatures that had thrived in tropical seas during glacial periods indicated that the earth's equatorial regions had kept close to their presentday temperatures.