biogenesis
Biogenesis referred to in the biology , the development of a biological structure or a new organism - under the basic condition to arise from existing forms of life. An example of this are birds that lay eggs, from which birds hatch.
Biogenesis - Abiogenesis
The term is used for the view that life can only be passed on from living beings, in contrast to abiogenesis , which says that life can also arise from non-living things under certain (largely still unknown) circumstances. Until the 19th century, it was generally believed, based on the observation that maggots or molds appeared to appear spontaneously when organic substances were left to their own devices, that the spontaneous emergence of life from dead matter was an everyday process. This was refuted in the 19th century, in particular by Louis Pasteur , when he showed that the organisms that until then were believed to arise spontaneously from dead matter were in fact derived from biological precursor organisms. Until today it has never been observed that life has emerged anew.
Law of biogenesis
«La génération spontanée est une chimère. »
" Spontaneous generation is a pipe dream"
The empirical results of Pasteur and other researchers were summarized in the expression omne vivum ex vivo ( Latin : "Everything living [comes] from living things."), Which is also known as the law of biogenesis . They claimed that life in its present forms does not arise spontaneously from non-living things. However, the results did not suggest the circumstances under which life arose.
The sentence "Everything living arises from living" contradicts the generally accepted standard model of cosmology , according to which (inanimate) matter did not even exist at the beginning of the universe (at the Big Bang ), but was made up of energy due to the equivalence of mass and energy educated. Continued logically , living things could only have arisen from living things that should have already existed at the Big Bang.
The “law of biogenesis” should not be confused with the “ basic biogenetic rule ” established by Ernst Haeckel in 1866 .
Human attempts to create life
Charles Darwin wrote in a letter to Joseph Dalton Hooker on February 1, 1871 , that life began in "a warm little pond in which all kinds of ammonia and phosphorus salts, light, heat, electricity, etc. were present." could have and “that a protein compound was chemically formed and was subject to even more complex changes. Nowadays something like that would be swallowed up or absorbed immediately, which was not the case before the living creatures came into being. ”Thus it is the presence of life itself that prevents abiogenesis from occurring on earth today.
There have been many efforts to create life from non-living things, but none have been successful so far. JB Burke tried to create small living cells from inorganic material with the help of radium ; only microscopic, exploding gas bubbles formed. Pflüger produced cyanic acid , which he compared to semi-living molecules , but it was just a dead chemical mixture. The Russian scientist Alexander Ivanovich Oparin pointed out that conditions on Earth at the time of the emergence of life were very different from today. The Miller-Urey experiment confirmed his hypothesis by producing some of the organic components of life from an atmosphere of methane , ammonia, and water vapor.
In 2002, scientists managed to artificially produce a poliovirus because the exact genetic blueprint was known and could be reproduced in the laboratory. Since then, other viruses have been produced synthetically . However, these experiments are not considered examples of abiogenesis, as viruses do not meet the standard criteria for life . They do not respond to stimuli , they are ataxic , they lack the ability or mechanism to grow or reproduce, and they have no cells.
Supporters of abiogenesis show these results as confirmation of their position, since non-living viruses and living bacteria are only “molecular machines” of varying complexity. Many of them expect scientists to be able to produce bacteria synthetically if the necessary technology is sufficiently advanced and thus offers the possibility of abiogenesis.
On the other hand, many scientists consider it unlikely that the complete process of life formation can ever be simulated in the laboratory. The reason for this is that, in their opinion, the process of the origin of life requires resources (time spans in the range of millions of years, size of the potential habitat) which are not available on a laboratory scale.
Web links
Individual evidence
- ↑ Scientists build poliovirus from scratch. ( Memento of March 29, 2005 in the Internet Archive ) On: cbc.ca of July 12, 2002
- ^ Scientists make artificial virus out of DNA. ( Memento of April 21, 2005 in the Internet Archive ) On: cbc.ca of November 14, 2003