Academic journal article
By Wagler, Ron
The American Biology Teacher , Vol. 73, No. 2
There have been five past great mass extinctions during the history of Earth. There is an ever-growing consensus within the scientific community that we have entered a sixth mass extinction. Human activities art" associated directly or indirectly with nearly every aspect of this extinction. This article presents an overview of the five past great mass extinctions; an overview of the current Anthropocene mass extinction; past and present human activities associated with the current Anthropocene mass extinction; current and future rates of species extinction; and broad science-curriculum topics associated with the current Anthropocene mass extinction that can be used by science educators. These broad topics are organized around the major global, anthropogenic direct drivers of habitat modification, fragmentation, and destruction; overexploitation of species; the spread of invasive species and genes; pollution; and climate change.
KeyWords: Biology curriculum; Anthropocene; extinction; anthropogenic; evolution.
* An Overview of Earth's Five Past Great Mass Extinctions
There have been five past great mass extinctions during the history of Earth (Jablonski, 1995; Erwin, 2001; see Figure 1). All five were characterized by "a profound loss of biodiversity during a relatively short period" (Wake & Vredenburg, 2008: p. 11466). The first mass extinction, the Ordovician-Silurian, occurred approximately (=) 439 million years ago (mya). The fifth, the Cretaceous-Tertiary, occurred [approximately equal to] 65 mya (Jablonski, 1995; Erwin, 2001). It was this extinction that saw the demise of the nonavian dinosaurs (Wake & Vredenburg, 2008). The most devastating mass extinction was the Permian-Triassic extinction ([approximately equal to] 251 mya), in which [approximately equal to] 95% of all global species went extinct (Jablonski, 1995; Erwin, 2001).
* An Overview of the Current Anthropocene Mass Extinction
There is an eve>growing consensus within the scientific community that we have entered a sixth mass extinction (McDaniel & Borton, 2002; Thomas et al., 2004; Lewis, 2006; Steffen et al., 2007; Alroy, 2008; Jackson, 2008; Rohr et al., 2008; Wake & Vredenburg, 2008; Rockstrom et al., 2009; Zalasiewicz et al., 2010). As Jeremy Jackson, director of the Center for Marine Biodiversity and Conservation and both the William E. and Mary B. Ritter Professor of Oceanography at the Scripps Institution of Oceanography and a senior scientist at the Smithsonian Tropical Research institute, has written:
The great mass extinctions of the fossil record were a major creative force that provided entirely new kinds of opportunities for the subsequent explosive evolution and diversification of surviving clades. Today, the synergistic effects of human impacts are laying the groundwork for a comparably great Anthropocene mass extinction ... with unknown ecological and evolutionary consequences. (Jackson, 2008: p. 11458)
In 2000, Paul Crutzen and Eugene Stoermer proposed that a new geological epoch had begun. They named the epoch the Anthropocene (pronounced an-thruh-po-seen) based on the "impact of human activities on earth and atmosphere" (Crutzen & Stoermer, 2000: p. 17). They stated that this geological epoch had begun in the "latter part of the 18th century" because by then "the global effects of human activities have become clearly noticeable" (Crutzen & Stoermer, 2000: p. 17). After this article and others (e.g., Crutzen, 2002; Crutzen & Steffen, 2003), the term "Anthropocene" entered the scientific lit erature informally (e.g., Steffen et al., 2004; Andersson et al., 2005; Crossland et al., 2005; Syvitski et al., 2005).
The Stratigraphy Commission of the Geological Society of London, by a large majority, decided in 2008 "that there was merit in considering the possible formalization of this term: that is, that it might eventually join the Cambrian, Jurassic, Pleistocene, and other such units on the Geological Time Scale" (Zalasiewicz et al. …