Biogenesis
From Wikipedia, the free encyclopedia
Biogenesis is the process of lifeforms producing other lifeforms, e.g. a spider lays eggs, which form into spiders.
The term is also used for the assertion that life can only be passed on by living things, in contrast to abiogenesis, which holds that life can arise from non-life under suitable circumstances, although these circumstances still remain unknown.
Until the 19th century, it was commonly believed that life frequently arose from non-life under certain circumstances, a process known as spontaneous generation. This belief was due to the common observation that maggots or mould appeared to arise spontaneously when organic matter was left exposed. It was later discovered that under all these circumstances commonly observed, life only arises from life.
A second, obsolete meaning of biogenesis was given by the French Jesuit priest, scientist and philosopher Pierre Teilhard de Chardin to mean the origin of life itself — now usually referred to as abiogenesis — reflecting the modern belief that the origin of life was from non-life.
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[edit] Law of biogenesis
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- "La génération spontanée est une chimère" ("Spontaneous generation is a dream") (Louis Pasteur)
Pasteur's (and others) empirical results were summarized in the phrase, Omne vivum ex vivo (or Omne vivum ex ovo, Latin for "all life [is] from life", also known as the "law of biogenesis". They showed that life does not spontaneously arise in its present forms from non-life in nature.
The "law of biogenesis" is not to be confused with Ernst Haeckel's Biogenetic Law. [1] [2]
The law of biogenesis was formulated after many years of extensive observation and experimentation. The ancient Greeks believed that living things could originate from nonliving matter (abiogenesis), and that the goddess Gea could make life arise spontaneously from stones. Aristotle disagreed, but still believed that creatures could arise from dissimilar organisms or from soil (an early form of evolution theory). 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, experiments, and arguments began that eventually discredited such ideas. This advance in scientific understanding was met with much opposition, with personal beliefs and individual predjudices often obscuring the facts. Francesco Redi, an Italian physician, proved as early as 1668 that higher forms of life could 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. In 1864 Louis Pasteur finally announced the results of his scientific experiments. In a series of neat experiments, Pasteur proved conclusively that only pre-existing microbes could give rise to other microbes (biogenesis). Thus Dr.Louis Pasteur finally overcame the longstanding belief in spontaneous generation of life. Even so, there were still people who chose to disregard the scientific evidence, and the 'belief' that life could spontaneously arise from non-life (abiogenesis) was still stubbornly held on to by some, including prominent, establishment figures such as Thomas Huxley ('Darwin's Bulldog').
In the present day, the law of biogenesis is well established, and it is generally accepted by scientists that abiogenesis has no scientific validity. The medical profession and food industry rely totally on the trustworthiness of the law of biogenesis for hygiene, sterilisation and food preservation.
No life has ever been observed to arise from non-living matter. However, the Miller-Urey experiment did show that amino acids, and other subsequent organic compounds, can be synthesized from simple carbon atoms in the early earth conditions.
[edit] Human attempts to create life
Charles Darwin in a letter to J.D. Hooker of February 1st 1871, made the suggestion that life may have begun in a "warm little pond, with all sorts of ammonia and phosphoric salts, lights, heat, electricity, etc. present, that a protein compound was chemically formed ready to undergo still more complex changes, at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed." Thus, it is the presence of life itself which prevents "spontaneous generation" from occurring on Earth today.
A number of efforts have been made to bring life from non-life, but there has been little success. J. B. Burke attempted to produce small living cells from inorganic matter by means of radium were unsuccessful; the radiobes produced were merely bursting gas bubbles of microscopic size. Pflüger produced cyanic acid, which he compared to half-living molecules, but it was merely a dead chemical compound. The Russian Scientist Alexander I Oparin suggested that we need to understand that the conditions on Earth at the time of the origin of life must have been very different from how they are today. The Miller-Urey experiment confirmed Oparin's hypothesis by producing some of the organic components of life, from an atmosphere of methane, ammonia and water vapour. The most basic amino acids were formed in Miller's test tube but the atmosphere required to make them killed them soon after. One of the greatest obstacles to abiogenesis is the origin of the information encoded in DNA in first life. According to the modern science of Information Theory; There is no known law of nature, no known process and no known sequence of events which can cause information to arise by itself in matter. THEOREM 28. and, Any model for the origin of life (and of information) based solely on physical and/or chemical processes, is inherently false. THEOREM 27
In 2002, scientists succeeded in constructing an artificial and "functioning" (able to infect and kill mice) Polio virus. Other viruses have since been synthesized. These experiments do not qualify as true examples of abiogenesis, since viruses do not meet the standard biological criteria for life. Primarily, they do not respond to stimuli, they are ataxic, they lack the ability or the mechanics to grow or reproduce on their own, and they do not possess cells.
Still, proponents of the idea of abiogenesis cite these results in support of their position, stating that both "non-living" viruses and "living" bacteria are solely "molecular machines" of different complexity. Many of them expect scientists to be able to synthesize the latter when the necessary technology has advanced to a sufficient level, thus proving the possibility of abiogenesis. Additionally, some point to lesser-known and controversial experiments such as those performed by Andrew Crosse as examples of abiogenesis.
Critics of abiogenesis point out that, thus far, life has not been oberved to be created without outside intelligence forcing environmental conditions necessary for life, so that abiogenesis seems unlikely to have occurred.
[edit] Law of Biogenesis and Creationism
The narrower meaning of the term Biogenesis is the basis of Creation biology, which holds that since life cannot arise spontaneously from non-life, life must, of necessity, have been created by a "supernatural" being, typically the Christian God. Supporters of the theory of evolution argue that creationists misuse the law of biogenesis to support their arguments. But it is clear that Pasteur and others proved by the scientific method of experiment and observation that no life of any kind will arise of its own accord from non-living matter (spontaneously generate) under any known circumstances. This holds true to the present day and there is still no known naturalistic mechanism whereby matter, and/or an interaction of undirected energy and matter, can spontaneously generate even a single, self-replicating, living cell. An even greater problem for the evolutionist critics of the creationist's insistence on the inviolability of the law of biogenesis is the origin the DNA code and the information carried by it. This encroaches on another scientific discipline, 'Information Theory' which rules out naturalistic creation of information. So, the law of biogenesis is now well established and can be reckoned to be reliable enough to be trusted to be true in all imaginable circumstances. Indeed, we rely on it to be true as the basis of modern, medical hygiene and food preservation.
Evolutionists also say that creationists' use of the law as an argument against theories of common descent is an example of the fallacy of false dilemma, since it is imaginable that a creator god created the LUCA or one of its ancestors, from which point on evolution occurred in a guided or unguided fashion. Creationists respond that abiogenesis is not a form of creationism, because it holds that life arises spontaneously, while creationism holds that life was deliberately created. Further, since the hypothesized development of "primitive life" from "increasingly complex molecules" has never been observed, there remains no comprehensive scientific justification for believing it has ever occurred. Finally, they argue that once it has been conceded (as is conceded by theistic evolution) that the original cell was created by a divine being, there is no reason to believe He could not have created life in a variety of forms.
