environmental changes typically cause
mass extinctions. More than 99.9 percent of all species that ever lived on Earth, amounting to over five billion species, are estimated to be
extinct. Estimates on the number of Earth's current
species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described. The total amount of related
DNAbase pairs on Earth is estimated at 5.0 x 1037 and weighs 50 billion
tonnes. In comparison, the total
mass of the
biosphere has been estimated to be as much as 4
TtC (trillion tons of
carbon). In July 2016, scientists reported identifying a set of 355
genes from the
Last Universal Common Ancestor (LUCA) of all
organisms living on Earth.
The term biological diversity was used first by wildlife scientist and conservationist Raymond F. Dasmann in the year 1968 lay book A Different Kind of Country advocating conservation. The term was widely adopted only after more than a decade, when in the 1980s it came into common usage in science and environmental policy.
Thomas Lovejoy, in the foreword to the book Conservation Biology, introduced the term to the scientific community. Until then the term "natural diversity" was common, introduced by The Science Division of
The Nature Conservancy in an important 1975 study, "The Preservation of Natural Diversity." By the early 1980s TNC's Science program and its head, Robert E. Jenkins, Lovejoy and other leading conservation scientists at the time in America advocated the use of the term "biological diversity".
Since this period the term has achieved widespread use among biologists, environmentalists, political leaders and concerned citizens.
A similar term in the United States is "natural heritage." It pre-dates the others and is more accepted by the wider audience interested in conservation. Broader than biodiversity, it includes geology and landforms.