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A scenario is a set of related concepts pertinent to the origin of life (abiogenesis), such as the iron-sulfur world. Many alternative abiogenesis scenarios have been proposed by scientists in a variety of fields from the 1950s onwards in an attempt to explain how the complex mechanisms of life could have come into existence. These include ...
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.
Bernal called this idea biopoiesis or biopoesis, the process of living matter evolving from self-replicating but non-living molecules, [17] [31] and proposed that biopoiesis passes through a number of intermediate stages. Robert Shapiro has summarized the "primordial soup" theory of Oparin and Haldane in its "mature form" as follows: [32]
What is Maslow’s hierarchy of needs? We explain the commonly circulated concept with some examples of how it translates in the real world.
Maslow’s hierarchy of needs is a conceptualisation of the needs (or goals) that motivate human behaviour, which was proposed by the American psychologist Abraham Maslow. [ 1 ] [ 2 ] According to Maslow’s original formulation, there are five sets of basic needs that are related to each other in a hierarchy of prepotency (or strength).
Spontaneous generation is a superseded scientific theory that held that living creatures could arise from nonliving matter and that such processes were commonplace and regular. It was hypothesized that certain forms, such as fleas , could arise from inanimate matter such as dust, or that maggots could arise from dead flesh.
Although alternative chemical paths to life have been proposed, [8] and RNA-based life may not have been the first life to exist, [3] [9] the RNA world hypothesis seems to be the most favored abiogenesis paradigm. However, even proponents agree that there is still not conclusive evidence to completely falsify other paradigms and hypotheses.
Haldane's article on abiogenesis in 1929 introduced the "primordial soup theory", which became the foundation for the concept of the chemical origin of life. He established human gene maps for haemophilia and colour blindness on the X chromosome , and codified Haldane's rule on sterility in the heterogametic sex of hybrids in species .