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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.
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 ...
This forms an important part of the evidence on which evolutionary theory rests, demonstrates that evolution does occur, and illustrates the processes that created Earth's biodiversity. It supports the modern evolutionary synthesis —the current scientific theory that explains how and why life changes over time.
Life arose from the Earth's first ocean, which formed some 3.8 billion years ago. [33] Since then, water continues to be the most abundant molecule in every organism. Water is important to life because it is an effective solvent , capable of dissolving solutes such as sodium and chloride ions or other small molecules to form an aqueous solution .
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.
The amount of gas a super-Earth that formed in situ acquires may depend on when the planetary embryos merged due to giant impacts relative to the dissipation of the gas disk. If the mergers happen after the gas disk dissipates terrestrial planets can form, if in a transition disk a super-Earth with a gas envelope containing a few percent of its ...
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]
Evolutionary thought, the recognition that species change over time and the perceived understanding of how such processes work, has roots in antiquity. With the beginnings of modern biological taxonomy in the late 17th century, two opposed ideas influenced Western biological thinking: essentialism, the belief that every species has essential characteristics that are unalterable, a concept ...