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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 first known mass extinction was the Great Oxidation Event 2.4 billion years ago, which killed most of the planet's obligate anaerobes. Researchers have identified five other major extinction events in Earth's history, with estimated losses below: [ 11 ]
The biosphere is postulated to have developed, from the origin of life onwards, at least some 3.5 billion years ago. [79] The earliest evidence for life on Earth includes biogenic graphite found in 3.7 billion-year-old metasedimentary rocks from Western Greenland [ 74 ] and microbial mat fossils found in 3.48 billion-year-old sandstone from ...
The timeline of human evolution outlines the major events in the evolutionary lineage of the modern human species, Homo sapiens, throughout the history of life, beginning some 4 billion years ago down to recent evolution within H. sapiens during and since the Last Glacial Period.
Human history or world history is the record of humankind from prehistory to the present. Modern humans evolved in Africa around 300,000 years ago and initially lived as hunter-gatherers. They migrated out of Africa during the Last Ice Age and had spread across Earth's continental land except Antarctica by the end of
The Origin of Life. The Weidenfeld and Nicolson Natural History. Translation of Oparin by Ann Synge. London: Weidenfeld & Nicolson. LCCN 67098482. Bondeson, Jan (1999). The Feejee Mermaid and Other Essays in Natural and Unnatural History. Ithaca, NY: Cornell University Press. ISBN 978-0-8014-3609-3. LCCN 98038295. Bryson, Bill (2004).
They may have lived as early as 4.28 Gya (billion years ago), relatively soon after the formation of the oceans 4.41 Gya, not long after the formation of the Earth 4.54 Gya. [ 78 ] Early micro-fossils may have come from a hot world of gases such as methane, ammonia, carbon dioxide, and hydrogen sulfide , toxic to much current life. [ 230 ]
The age of the Earth is about 4.5 billion years. [1] [2] [3] The earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago. [4] [5] [6] Evolution does not attempt to explain the origin of life (covered instead by abiogenesis), but it does explain how early lifeforms evolved into the complex ecosystem that we see ...