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The Afroasiatic languages, as they are distributed today. The Proto-Afroasiatic homeland is the hypothetical place where speakers of the Proto-Afroasiatic language lived in a single linguistic community, or complex of communities, before this original language dispersed geographically and divided into separate distinct languages.
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. [32] [33 ...
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 ...
[4] [5] Charles Darwin more famously proposed the theory of universal common descent through an evolutionary process in his book On the Origin of Species in 1859: "Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first ...
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. [36] [37] The oldest evidence of life is indirect in the form of isotopic ...
If the deep marine hydrothermal setting was the site for the origin of life, then abiogenesis could have happened as early as 4.0-4.2 Gya. If life evolved in the ocean at depths of more than ten meters, it would have been shielded both from impacts and the then high levels of ultraviolet radiation from the sun.
Obcells are hypothetical proto-organisms or the earliest form of life. The term was first proposed by Thomas Cavalier-Smith in 2001. According to Cavalier-Smith's theory for the origin of the first cell, two cup-shaped obcells or hemicells fused to make a protocell with double-lipid layer envelope, internal genome and ribosomes, protocytosol, and periplasm.
Long before the appearance of compartmentalized biological entities like FUCA, life had already begun to organize itself and emerge in a pre-cellular era known as the RNA world. [4] The universal presence of both biological translation mechanism and genetic code in every biological systems indicates monophyly , a unique origin for all ...