<\/p>\n
Speciation and extinction are ordinary processes in the natural world. The fossil record suggests that most of the species that have ever lived on Earth have gone extinct.\u00a0 About 10 million species of higher organisms now occupy the world. Averaged over long periods, about one species goes extinct each year for every one million species that are present. Thus, at nominal rates, about 10 should go extinct this year. Most, being very small and perhaps still without a name, will disappear quietly without notice.<\/p>\n
The species disappearing are presumably balanced by new species evolving to join the Earth\u2019s biodiversity. The evolution of new species is also a natural process, albeit at extremely slow rates. Conservation biologists have been looking for the appearance of a new species for the past 100 years or so, and I have yet to see a report of even one such event.<\/p>\n
The long-term average rate of extinction masks periods of mass extinction in Earth\u2019s history. \u00a0Digging through this record, paleontologists see five major periods of extinction, when lots of species disappeared in a relatively short period of time.\u00a0 One of these about 65 million years ago, took the dinosaurs.<\/p>\n
Today, the rate of species loss is about 100 to 1000 times greater than the long-term historical record.\u00a0 Are we entering another epoch of mass extinction?\u00a0 Are humans to blame?\u00a0 Will we be haunted by the ghost of extinctions past?<\/p>\n
Unfortunately the answer to these questions seems to be \u201cyes.\u201d\u00a0 Currently, we are witnessing a major extinction of the Earth\u2019s species at our own hands. \u00a0Loss of habitat is likely to be the largest cause of species extinction, as we usurp natural land for agriculture, roads, and habitation. \u00a0Upon habitat conversions, more than 75 percent of local species are usually lost, and the abundance of those remaining is reduced nearly 40 percent.<\/p>\n
Introductions of species from far-off lands, which out-compete species at home, are also a major cause of extinction. \u00a0The native birds of Hawaii are largely extinct in the face of competition from introduced, exotic competitors and avian malaria. \u00a0We are homogenizing the diversity of the world and in the process losing a considerable amount of its richness.<\/p>\n
Armed conflict, hunting and poaching are likely to cause the extinction of some of the remaining big animals in Africa, and projected changes in climate are estimated to drive about one-third of today\u2019s species extinct within a few centuries.<\/p>\n
Setting aside the Passenger Pigeon, which humans set upon with unusual vengeance, the most vulnerable species are those with relatively small population sizes and limited range.\u00a0 In the United States, these are species that the Endangered Species Act was designed to save.\u00a0 But rare species are also found throughout the world, where their protection is limited.\u00a0 Bird-watchers and those on safari pay big money to go see them.<\/p>\n
There are lots of reasons to preserve species.\u00a0 Some species are of economic value for timber, fisheries, and ecotourism.\u00a0 Others aid human health, provide and protect agricultural crops, and lower damages to human infrastructure.\u00a0 The loss of the wolf as a predator of white-tailed deer in the eastern United States is now associated with the expenditure of $4 billion each year for repairs to automobiles that collide with deer.<\/p>\n
Sometimes, we can substitute human ingenuity to perform the function of species, often at considerable incremental cost.\u00a0 Loss of the predators of insects that feed on crops is the basis of a large portion of the $29 billion that is spent on pesticides each year. These pesticides often poison species, including us, that were not intended as targets.<\/p>\n
Being a relatively new species to evolve on Earth and possessing putative sapiens <\/em>skills, humans have a compelling ethos to preserve biodiversity.\u00a0 As Michael Northcott points out, in the correct Hebrew translation of the Bible, God instructs humans not only to have dominion, but to be a steward of the natural world.\u00a0 Certainly, we should not stand by and shrug our shoulders when we hear that humans have endangered a species, which is now likely to go extinct. The world will be a less healthy, less productive, and less interesting place when it is impoverished of nature.<\/p>\n Each year, people are born and people die.\u00a0 That\u2019s natural, but when we cause someone to die, it\u2019s called murder. Murder is unethical.<\/p>\n Each year species appear and species disappear. That\u2019s natural, but when humans eliminate a species, it\u2019s called extinction\u2014the equivalent of murder.\u00a0 Extinction is unethical.<\/p>\n Like it or not, we are keepers of the biosphere, and our judgment day will assess how well we did.<\/p>\n <\/p>\n References<\/p>\n Barnosky, A.D. and 11 others. 2011. Has the Earth\u2019s sixth mass extinction already arrived?\u00a0 Nature 471: 51-57.<\/p>\n Keesing, F. and 11 others. 2010.\u00a0 Impacts of biodiversity on the emergence and transmission of infectious diseases.\u00a0 Nature 468: 647-652.<\/p>\n Newbold, T. and 40 others. 2015.\u00a0 Global effects of land use on local terrestrial biodiversity.\u00a0 Nature 520: 45-50.<\/p>\n Northcott, M.\u00a0 1996\u00a0\u00a0 The Environment and Christian Ethics<\/em>.\u00a0 Cambridge University Press.<\/p>\n Pimm, S.L., G.J. Russell, J.L. Gittleman, and T.M. Brooks.\u00a0 1995. The future of biodiversity. Science 269: 347-350.<\/p>\n Thomas, C.D. and 18 others. 2004.\u00a0 Extinction risk from climate change.\u00a0 Nature 427: 145-148.<\/p>\n","protected":false},"excerpt":{"rendered":" We are keepers of the biosphere, and our judgment day will assess how well we did.<\/p>\n","protected":false},"author":517,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[192,82,5],"tags":[294],"coauthors":[6],"class_list":["post-691","post","type-post","status-publish","format-standard","hentry","category-biodiversity","category-conservation","category-faculty","tag-extincton"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5KxUl-b9","post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/posts\/691","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/users\/517"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/comments?post=691"}],"version-history":[{"count":1,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/posts\/691\/revisions"}],"predecessor-version":[{"id":692,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/posts\/691\/revisions\/692"}],"wp:attachment":[{"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/media?parent=691"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/categories?post=691"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/tags?post=691"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/blogs.nicholas.duke.edu\/citizenscientist\/wp-json\/wp\/v2\/coauthors?post=691"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}