Museum is especially important to the science of 

 diversity because it is one of the world's four largest 

 natural history museums and has a principal focus in 

 the tropics. Three of the Museum's four scientific 

 departments (Botany, Geology, and Zoology) focus on 

 biological diversity, its origins, interrelationships, and 

 conservation. Each day, museum scientists discover 

 diversity in nature, document it through collections 

 and study, and disseminate this information to others 

 through scholarly publications and public programs. 

 Many of these contributions are significant to 

 conservation. 



I will try here to identify some key relationships 

 between Field Museum's scientific programs and trop- 

 ical conservation. Although my review is far from 

 comprehensive, it may serve to indicate the range and 

 value of efforts now underway. Readers interested in 

 further information on these programs are encouraged 

 to contact the Museum's Development Office or 

 scientific departments. 



The Diversity Crisis: 

 Causes and Consequences 



According to current estimates, at least half of all life 

 on earth is threatened with extinction over the next 

 150 years. The reasons for this calamity do not involve 

 the "death star," Nemesis, or climatic catastrophes, 

 which may have caused massive extinctions in the 

 past. Today's extinction wave is the direct result of nat- 

 ural habitats being converted for human use. 



Wholesale habitat conversion is proceeding at dif- 

 ferent rates in different regions. The most alarming and 

 biologically significant form of habitat conversion is 

 taking place in wet tropical forests. Tropical moist for- 

 ests now cover a scant 6 percent of earth's land area but 

 support at least half of all living species. Most of these 

 forests are in developing countries that have expanding 

 human populations and economies overburdened by 

 debt to creditor nations. The forests represent uninha- 

 bited frontiers for new human settlements and ex- 

 panded agricultural production. Additionally, trade 

 based on forest commodities provides a major source of 

 foreign currencies, which are needed for economic and 

 social development. 



Given this political, economic and social con- 

 text, tropical forests are under relentless exploitation. 

 An estimated 71,000-92,000 sq. km (about 27,000- 

 35,500 sq. mi.) of tropical moist forest lands are de- 

 nuded each year, and 119,000-200,000 sq. km are 

 seriously degraded. This scale of destruction is hard to 



imagine and impossible to accept. If you are not already 

 committed to conservation, use your next cross-town 

 trip to imagine the sight of fallen forest giants and 

 wandering, homeless animals stretching from Evan- 

 ston to Hammond and west to Oak Park — this much 

 devastation happens each day in the world's tropical for- 

 ests. Tropical forests today cover only two-thirds of 

 their extent two or three centuries ago. If deforestation 

 continues at current rates, a fifth of the remaining for- 

 ests will be cut over by the year 2000 and the last rem- 

 nant patches would disappear entirely in 150 years. 

 However, growing human populations, especially in 

 the Third World, will probably destroy these habitats 

 much more quickly. 



Extinction of species is an inevitable outcome of 

 habitat destruction. Is this all bad? Geological studies 

 tell us that all species eventually go extinct, making 

 room for new forms that constitute evolutionary ex- 

 periments; further, extinctions have claimed an esti- 

 mated 99 percent of all species that have appeared 

 through geological time. Even so, today's high standing 

 diversity indicates that, over time, many more new 

 species have been produced than those that dis- 

 appeared. Much of systematics, the science of biologi- 

 cal diversity, focuses on factors affecting the production 

 of new species, the loss of existing ones, and the bal- 

 ance between these opposing rates. 



Since its emergence, our species has played an in- 

 creasingly dominant role as an agent of extinction. At 

 the end of the last Ice Age, when climates were in great 

 flux but human economies were mostly of the hunter- 

 gatherer kind, about two species of birds and two spe- 

 cies of mammals went extinct each century. Human 

 hunters may have contributed to the sudden extinc- 

 tions of large vertebrates (the "overkill hypothesis" of 

 Paul Martin at the University of Arizona), but rapid 

 climatic changes may also have been involved in the 

 disappearance of these forms. Between 1600 and 1900 

 AD, when climates were stable but human technologies 

 were considerably more developed, extinction rates in- 

 creased ten-fold: roughly 10 mammal species and 27 

 bird species went extinct each century. Most extinc- 

 tions during this period resulted from direct human 

 persecution — Steller's sea cows, Tasmanian marsupial 

 wolves, passenger pigeons, and dodo birds would still 

 exist today but for humans. A host of other species only 

 narrowly escaped extinction (perhaps not for long), 

 including whales, bison, and cranes. 



Today, human-caused extinctions are rapidly 

 accelerating and now vastly exceed the origination of 

 new species by evolution. Direct persecution of some 



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