As man invades tropical regions for timber, farming, and other development, the rain forest continues to disappear, and hundreds of thousands of species vanish into extinction. As a result, the earth is robbed of one of its most precious resources — biodiversity.
Fortunately for mankind, life beneath the rainforest is as rich — if not more so — than life above ground. For the past 35 years an Italian speleologist and professor of zoology named Valerio Sbordoni has explored the caves and sotanos, or subterranean chambers, of Mexico in search of new forms of life. He has found them in abundance. To date Sbordoni has discovered more than 150 species of hitherto unknown cave-dwelling creatures. In one sotano alone he found 42 distinct species of butterflies, an incredible variety for such an inhospitable environment.
Many of these species, Sbordoni believes, retreated underground millions of years ago to avoid extinction and adapted to unique conditions far beneath the earth’s surface. If so, their existence lends hope for the future and even possible regeneration of the rainforest. “If we are able to maintain these components of diversity," Sbordoni explains, "there is the possibility that the tropical rainforest may spread again and regenerate even after a long arid period has intervened."
Conditions for life beneath the surface are far from ideal, and Sbordoni believes that only severe climatic changes could have driven so many creatures underground. "We believe that nearly all of these species had ancestors living on the earth, and only such massive changes could account for the migration. The changes probably occurred toward the end of the last Ice Age, when glaciers retreated from vast areas of the earth and temperatures began to vary."
Much of Sbordoni’s work has been done in Mexico’s state of Chiapas, where the caves and sotanos can reach depths of 350 metres and only expert speleologists can survive in them. Sbordoni has explored 140 such caves and sotanos. At 56, he combines the skills of a world-class rock climber with an unparalleled knowledge and understanding of subterranean life.
With over 250 articles and seven books to his credit, Sbordoni enjoys a brilliant academic career. But his heart remains in the field, where to date he has led or taken part in 31 expeditions in more than a dozen countries. Few scientists have exhibited such devotion, enterprise and courage, risking his safety in the search for new knowledge underground. It is for this spirit that Sbordoni was honoured as an Associate Laureate in the 1998 Rolex Awards for Enterprise.
Dr. Pierre Strinati of Switzerland, himself a renowned biospeleologist, points out that until Sbordoni began his study of fauna in tropical caves, the scientific world considered the subject of little interest. "Sbordoni is one of the great world specialists in cave fauna," says Strinati. "It is in part due to his expeditions that the diversity of the fauna of caves situated in the tropics was discovered, when it was thought that there was very little."
To Valerio Sbordoni the caves and sotanos are unique to the study of life in perpetual change. "They are an extraordinary laboratory for the study of evolution of species," he says, "and they have helped us to calibrate the so-called molecular clock, which records the entire process of evolutionary change."
Many of the creatures Sbordoni has discovered exhibit remarkable adaptations to subterranean life. In the semi-darkness of sotanos most species have smaller eyes, less skin pigmentation, and longer legs and antennae than their counterparts on the surface. At the same time their other sensory organs appear far more developed than those of the surface-dwellers.
These discoveries lend weight to the refugium — or refuge — theory, which holds that cave populations are the descendants of long-ago species that retreated underground in order to survive and then adapted to a different environment.
So far Sbordoni has concentrated on the creatures that inhabit the floors and underground streams of the sotanos. Support from his Rolex Award, however, will help him focus on a new and different area. He plans the exploration of six more caves in Chiapas in a series of journeys from 1998 until the year 2000. During these expeditions he will turn his attention upward, to species that frequent the forest canopies of the caves. He will compare these with canopy-dwellers on the surface, recording their similarities and their differences. These findings may add further support to the refugium theory.
Published in 1998