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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 ...
Starting in 1985, researchers proposed that life arose at hydrothermal vents, [230] [231] that spontaneous chemistry in the Earth's crust driven by rock–water interactions at disequilibrium thermodynamically underpinned life's origin [232] [233] and that the founding lineages of the archaea and bacteria were H 2-dependent autotrophs that used ...
A tree of life, like this one from Charles Darwin's notebooks c. July 1837, implies a single common ancestor at its root (labelled "1").. A phylogenetic tree directly portrays the idea of evolution by descent from a single ancestor. [3]
The timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth. Dates in this article are consensus estimates based on scientific evidence , mainly fossils .
The tree of life or universal tree of life is a metaphor, conceptual model, and research tool used to explore the evolution of life and describe the relationships between organisms, both living and extinct, as described in a famous passage in Charles Darwin's On the Origin of Species (1859). [1]
[12] [13] Darwin noted that orchids have complex adaptations to ensure pollination, all derived from basic floral parts. Darwin gained extensive experience as he collected and studied the natural history of life forms from distant places. Through his studies, he formulated the idea that each species had developed from ancestors with similar ...
The RNA world hypothesis, if true, has important implications for the definition of life and the origin of life. For most of the time that followed Franklin , Watson and Crick 's elucidation of DNA structure in 1953, life was largely defined in terms of DNA and proteins: DNA and proteins seemed the dominant macromolecules in the living cell ...
Evolutionary biology – study of the origin and descent of species over time. Evolutionary developmental biology – field of biology that compares the developmental processes of different organisms to determine the ancestral relationship between them, and to discover how developmental processes evolved.