Spontaneous generation
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| - | :''[[Spontaneous generation]]'' | ||
| - | '''Biogenesis''' is the process of [[life]]forms producing other lifeforms, e.g. a [[spider]] lays eggs, which develop into spiders. It may also refer to biochemical processes of production in living organisms. | ||
| - | ==Generatio spontanea== | + | '''Spontaneous generation''' or '''Equivocal generation''' is an obsolete theory regarding the [[origin of life]] from inanimate matter, which held that this process was a commonplace and everyday occurrence, as distinguished from '''univocal generation''', or reproduction from parent(s). The theory was synthesized by [[Aristotle]], who compiled and expanded the work of prior natural philosophers and the various ancient explanations of the appearance of organisms; it held sway for two millennia. It is generally accepted to have been ultimately disproven in the 19th Century by the experiments of [[Louis Pasteur]], expanding upon the experiments of other scientists before him (such as [[Francesco Redi]] who had performed similar experiments in the 17th century). Ultimately, it was succeeded by [[germ theory of disease|germ theory]] and [[cell theory]]. |
| - | :''[[Spontaneous generation]]'' | + | |
| - | The ancient Greeks believed that living things could spontaneously come into being from nonliving matter, and that the goddess [[Gaia (mythology)|Gaia]] could make life arise spontaneously from stones – a process known as ''Generatio spontanea''. [[Aristotle]] disagreed, but he still believed that creatures could arise from dissimilar organisms or from soil. Variations of this concept of spontaneous generation still existed as late as the 17th century, but towards the end of the 17th century a series of observations and arguments began that eventually discredited such ideas. This advance in scientific understanding was met with much opposition, with personal beliefs and individual prejudices often obscuring the facts. | + | |
| - | [[Francesco Redi]], an Italian physician, proved as early as 1668 that higher forms of life did not originate spontaneously, but proponents of [[abiogenesis]] claimed that this did not apply to microbes and continued to hold that these could arise spontaneously. Attempts to disprove the spontaneous generation of life from non-life continued in the early 1800s with observations and experiments by [[Franz Schulze]] and [[Theodor Schwann]]. | + | The disproof of ongoing spontaneous generation is no longer controversial, now that the life cycles of various life forms have been well documented. However, the question of [[abiogenesis]], how living things originally arose from non-living material, remains relevant today. |
| - | In 1745 [[John Needham]] added chicken broth to a flask and boiled it. He then let it cool and waited. Microbes grew and he proposed it as an example of spontaneous generation. In 1768 [[Lazzaro Spallanzani]] repeated Needham's experiment, but removed all the air from the flask. No growth occurred. | + | |
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| - | In 1864, [[Louis Pasteur]] finally announced the results of his scientific experiments. In a series of experiments similar to those performed earlier by Needham and Spallanzani, Pasteur demonstrated that life today does not arise in areas that have not been contaminated by existing life. Pasteur's empirical results were summarized in the phrase, ''Omne vivum ex ovo'', Latin for ''all life [is] from eggs''. | + | |
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Spontaneous generation or Equivocal generation is an obsolete theory regarding the origin of life from inanimate matter, which held that this process was a commonplace and everyday occurrence, as distinguished from univocal generation, or reproduction from parent(s). The theory was synthesized by Aristotle, who compiled and expanded the work of prior natural philosophers and the various ancient explanations of the appearance of organisms; it held sway for two millennia. It is generally accepted to have been ultimately disproven in the 19th Century by the experiments of Louis Pasteur, expanding upon the experiments of other scientists before him (such as Francesco Redi who had performed similar experiments in the 17th century). Ultimately, it was succeeded by germ theory and cell theory.
The disproof of ongoing spontaneous generation is no longer controversial, now that the life cycles of various life forms have been well documented. However, the question of abiogenesis, how living things originally arose from non-living material, remains relevant today.
