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Science and the Endangered Species Act (1995) / Chapter Skim
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Pages 18-23

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From page 19...
... , we now can correlate many biotic and abiotic events in earth history with reasonable accuracy. What we learn from studying the past is important for predicting biotic responses to future changes in climate and other physical phenomena (Burney, 19931.
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From page 20...
... PREHISTORIC HUI\lAN IMPACT ON CONTINENTAL ECOSYSTEMS Although the causes of the P-T and K-T extinction events are topics of much interest, research, and speculation (e.g., lablonski, 1991; Kerr, 1993b; Morell, 1993; Sharpton et al., 1993)
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From page 21...
... As far as can be determined, human activity has significantly increased rates of extinction perhaps by orders of magnitude over the background rate (see below) and therefore is the primary cause of the current extinction event (Wilson, 19921.
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From page 22...
... Because of the good water supply and fertile alluvial soils, much early agriculture developed along major river valleys; consequently, riparian biotas have been disturbed for centuries, if not millennia (Rea, 19831. Chaco Canyon, New Mexico, is a clear example of prehistoric overexploitation of natural resources, as revealed by studies of plant macrofossils from ancient packrat middens (Betancourt and Van Devender, 1981; Betancourt et al., 19861.
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From page 23...
... Because of human activities that began more than 1,000 years ago, Chaco Canyon still sustains impoverished plant and animal communities and remains a poor place for people to live. Another example of prehistoric humans having a significant effect on the carrying capacity of their ecosystems involves the Aleuts, whose overexploitation of sea otters appears to have changed the coastal ecosystems of the Aleutian Islands as long as 2,500 years ago (Simenstad et al., 1978~.
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Key Terms

  • endangered species
  • chaco canyon
  • extinction event
  • late pleistocene
  • human predation

  • geological time
  • animal communities
  • current extinction
  • habitat modification
  • california condor

  • habitat changes
  • extinct species
  • extinction events
  • plant communities
  • fossil record

  • prehistoric human
  • threatened species
  • climatic change
  • prehistoric peoples
  • abiotic events

  • interglacial intervals
  • pacific islands
  • physical phenomena
  • water supply
  • ice cores

  • direct human
  • radiometric dating
  • avian malaria
  • biotic responses
  • reasonable accuracy


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