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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 transition from non-life to life has never been observed experimentally, but many proposals have been made for different stages of the process. The study of abiogenesis aims to determine how pre-life chemical reactions gave rise to life under conditions strikingly different from those on Earth today.
However, viruses are still poorly understood and may have arisen before "life" itself, or may be a more recent phenomenon. Major extinctions in terrestrial vertebrates and large amphibians. Earliest examples of armoured dinosaurs. 195 Ma First pterosaurs with specialized feeding (Dorygnathus). First sauropod dinosaurs.
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.
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).
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.
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 ...
"My parents and early friends put me in a position to have a wonderful life and be extremely lucky and be at the center of the digital revolution,” he tells PEOPLE — so he thought ...