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The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.
A life form (also spelled life-form or lifeform) is an entity that is living, [1] [2] such as plants , animals , and fungi . It is estimated that more than 99% of all species that ever existed on Earth, amounting to over five billion species, [3] are extinct. [4] [5] Earth is the only celestial body known to harbor life forms. No form of ...
Over time these evolutionary processes lead to formation of new species , changes within lineages , and loss of species . "Evolution" is also another name for evolutionary biology , the subfield of biology concerned with studying evolutionary processes that produced the diversity of life on Earth.
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Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]
The Origin and Nature of Life on Earth: The Emergence of the Fourth Geosphere (2016) is a book by Eric Smith and biophysicist Harold J. Morowitz which provides an introduction to origins of life research via a review of perspectives from a variety of fields active in this research area, including geochemistry, biochemistry, ecology, and microbiology.
Much Earth System science therefore relies on studies of the Earth's past behaviour and models to anticipate future behaviour in response to pressures. Life: Biological processes play a much stronger role in the functioning and responses of the Earth System than previously thought. It appears to be integral to every part of the Earth System.