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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.
Panspermia did not get much scientific support and deflects the need of an answer instead of explaining observable phenomena. Although interest in panspermia grew when traces of organic materials were found in meteorites, it is currently accepted that life started locally on Earth. [33]
All life on Earth can be traced back to a Last Universal Common Ancestor, or LUCA—and it likely lived on Earth only 400 million years after its formation. ... Life on Earth had to begin ...
The age of Earth is about 4.54 billion years; [7] [33] [34] the earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago according to the stromatolite record. [35] Some computer models suggest life began as early as 4.5 billion years ago.
For decades, scientists have theorized that volcanic lightning on an early Earth played a crucial role in kickstarting life on the planet by breaking molecules into useful, biological components.
In his book The Origin of Life, [29] [30] he proposed (echoing Darwin) that the "spontaneous generation of life" that had been attacked by Pasteur did, in fact, occur once, but was now impossible because the conditions found on the early Earth had changed, and preexisting organisms would immediately consume any spontaneously generated organism.
All life on Earth is based on carbon and is built from organic compounds including the amino acids used to create proteins and nucleobases. A nucleobase is a nitrogen-containing compound that ...