INSIGHTS: Human Activities Cause of Current Extinction Crisis

By E.O. Wilson, Paul R. Ehrlich, Stuart Pimm, Peter Raven, Gordon Orians, Jared Diamond, Harold Mooney, Daniel Simberloff, David Wilcove, and James Carlton

{Editor's Note: In a letter Tuesday to members of the U.S. Senate Environment and Public Works Subcommittee on Fisheries, Wildlife and Water, these 10 scientists warn that the Earth is losing species at an unprecedented rate and ask that Congress strengthen, not weaken, the Endangered Species Act.}

WASHINGTON, DC, May 19, 2005 (ENS) - "As scientists from across the United States with many years of experience in ecology, wildlife, conservation biology, evolutionary biology, we would like to share with you our views on the current extinction crisis. We write out of deep and growing concern for biological diversity; the full array of life on Earth, including the vast number of species of plants, animals, fungi, and micro-organisms and the natural communities that these species form.

Biological diversity at all levels is tremendously important to humankind. For example, hundreds of medicines and other compounds vital to human health are derived from the natural world. Some of them come from unlikely sources, exemplifying the need to protect as many species as possible:

  • A bacterium (Thermus aquaticus) that lives in hot springs in Yellowstone National Park is the source of a compound called "Taq polymerase," an enzyme required for DNA fingerprinting in forensics and diagnostics.

  • The important cancer treatment drug taxol is derived from the bark of the Pacific yew tree (Taxus brevifolia).

  • A protein found in the blood of horseshoe crabs (Limulus polyphemus) is used to detect bacterial toxins in all medical implants and injectable medicines and vaccines.


    The po'ouli, a small honeycreeper found only on the island of Maui, went extinct on November 28, 2004 when the last bird died. Many of the surviving native Hawaiian forest birds are slipping towards extinction. (Photo credit unknown)
    Wild plant and animal species are the source of virtually all domesticated foods and fibers. Even today breeders turn to wild specimens for genes that help crops resist pests, survive drought, and adapt to different growing conditions. Hence, the value of genetic diversity, or variety within species, speaks to the need to preserve more than just a few examples of each species. Perhaps even more important, however, is the value of full, intact ecosystems, which provide ecological services such as erosion control, water filtration, climate regulation, flood control and pollination.

    Despite the incredible importance of biological diversity, a grim scientific consensus is emerging: we are in the throes of an extinction crisis. Extinction is the irrevocable disappearance of a species everywhere on planet Earth. Unlike 'extirpation', which refers to a species disappearing from a particular jurisdiction (such as one state or country), extinction cannot be undone. Extinction is the killing off of all individuals, forever extinguishing the life of an entire species.

    Currently there is little doubt left in the minds of professional biologists that Earth is faced with a mounting loss of species that equals or exceeds any mass extinction in the geological record. Human activities have brought the Earth to the brink of this crisis.


    Dr. Paul R. Ehrlich is Bing Professor of Population Studies and president of the Center for Conservation Biology at Stanford University. (Photo courtesy Stanford)
    Many biologists consider that coming decades will see the loss of large numbers of species; these extinctions will alter not only biological diversity but also the evolutionary processes by which diversity is generated and maintained. Extinction is now proceeding one thousand times faster than the planet's historic rate.

    As of 2000, a total of 539 species out of roughly 200,000 in the United States have been recorded by NatureServe as extinct or missing. Of these, 100 meet the stricter criteria of presumed extinct, with the remaining 439 falling into the possibly extinct category.


    Dr. Edward Osborne Wilson is the Pellegrino University Professor Emeritus and honorary curator in entomology at Harvard University, where he has studied and worked for the past 54 years. (Photo courtesy Harvard University)
    These extinctions span the gamut of organisms, including vertebrates such as the great auk and West Indian monk seal, plants like the Santa atalina monkeyflower and falls-of-the-Ohio scurf-pea, and invertebrates such as the Wabash riffleshell and the Colorado burrowing mayfly.

    In the United States, there have been more extinctions of birds than of any other group of vertebrates - 2.3 percent of our endemic bird species are gone forever. The most current NatureServe data shows 30 bird pecies in all that are either presumed extinct or missing and possibly extinct. The majority of these birds (23 species) were native only to Hawaii.

    Four species native to the continental United States are presumed extinct: the passenger pigeon, Carolina parakeet, the great Auk, and Labrador duck. Furthermore, in the past 100 years the United States has lost 2.2 percent of its endemic amphibians, 1.2 percent of the freshwater fishes, 1.1 percent of the plant species, and a staggering 8.6 percent of the freshwater mussels forever.

    Worldwide, the situation is even worse. Because of the incredible density of species in tropical regions that are facing rapid deforestation, we may be losing species at a rate of 30,000 per year, or an overwhelming three per hour. Many biologists predict that coming decades will see the loss of large numbers of species.

    One quarter of all mammals, including lions, tigers, rhinos, and most primates, could be declared extinct by the end of this century, along with one in eight bird species, and thousands of plant species. Habitat destruction is widely recognized as the primary cause of species loss.


    Dr. Peter Raven is director of the Missouri Botanical Garden and adjunct professor at the University of Missouri, St. Louis University, and Washington University. (Photo courtesy St. Louis Earth Day)
    In the United States, habitat loss threatens about 85 percent of imperiled species. Worldwide, the figure may be higher. Agriculture, logging, urban development, dredging, damming, mining and drilling are just a few of the activities that eliminate or significantly degrade habitats. Invasive species released intentionally or imported accidentally take over habitats and crowd out native species. Similarly, diseases imported to areas where the local flora and fauna have no resistance also wreak havoc on biological diversity.

    Pollution, overexploitation, and global warming are also responsible for sending numerous species toward extinction. The future of humanity is inextricably tied to the fate of the natural world. In perpetuating this, the Earth's sixth mass extinction, we may ultimately compromise our own ability to survive. We need to steer this nation and lead the world towards a more sustainable path.


    David Wilcove is professor of ecology and evolutionary biology and public affairs at Princeton University. (Photo courtesy Princeton)
    As a result of the Endangered Species Act, passed in 1973 by an overwhelming Congressional majority, the United States maintains a Federal list of Endangered and Threatened Wildlife and Plants. The Endangered Species Act represents our nation's most determined effort to take responsibility for preserving its precious biological diversity. By offering strict federal protections to the species that are included on the list, the government has drawn a line which it will not allow human pressures to cross over. That line is extinction.

    In both its scope and its irreversibility, extinction is the most frightening, most conclusive word in our language. When a species has been declared extinct, not only have all its individuals died, but the possibility of any such individuals ever existing again has been foreclosed. The variety of life with which we share the earth is sadly in rapid decline. Life is rounded in biological diversity, and the fate of this diversity, which created and sustains us, is now in our hands.

    Fortunately, we have the wherewithal and the tools we need to address this crisis. The most important of them is the Endangered Species Act. It is the alarm system our nation crafted to warn us when species are facing extinction. It is the measure by which we halt species' decline and give species a fighting chance at recovery. Viewing our looming extinction crisis as a crisis for humans as well as wildlife, the importance of the Endangered Species Act takes on even greater significance. In the face of this crisis, we must strengthen the Act and broaden its protections, not weaken them.

    Thank you for considering our concerns and recommendations.

    The letter is addressed to:
    Senator Lincoln Chafee
    Chair, Environment and Public Works Subcommittee on Fisheries, Wildlife and Water

    Honorable Senator Hillary Rodham Clinton
    Ranking Member

    With copies to Committee Members: Senators John Warner, Lisa Murkowski, Jim DeMint, David Vitter, Joseph Lieberman, Frank Lautenberg, and Barack Obama