Chemical Evolution - The primitive Earth
atmosphere life water rna
Chemical evolution describes chemical changes on the primitive Earth that gave rise to the first forms of life. The first living things on Earth were prokaryotes with a type of cell similar to present-day bacteria. Prokaryote fossils have been found in 3.4-million-year-old rock in the southern part of Africa, and in even older rocks in Australia, including some that appear to be photosynthetic. All forms of life are theorized to have evolved from the original prokaryotes, probably 3.5-4.0 billion years ago.
The chemical and physical conditions of the primitive Earth are invoked to explain the origin of life, which was preceded by chemical evolution of organic chemicals. Astronomers believe that 20-30 billion years ago, all matter was concentrated in a single mass, and that it blew apart with a "big bang." In time, a disk-shaped cloud of dust condensed and formed the Sun, and the peripheral matter formed its planets. Heat produced by compaction, radiation, and impacting meteorites melted Earth. Then, as the planet cooled, Earth's layers formed. The first atmosphere was made up of hot hydrogen gas, too light to be held by Earth's gravity. Water vapor, carbon monoxide, carbon dioxide, nitrogen, and methane replaced the hydrogen atmosphere. As Earth cooled, water vapor condensed and torrential rains filled up its basins, thereby forming the seas. Also present were lightning, volcanic activity, and ultraviolet radiation. It was in this setting that life began.
According to one theory, chemical evolution occurred in four stages.
In the first stage of chemical evolution, molecules in the primitive environment formed simple organic substances, such as amino acids. This concept was first proposed in 1936 in a book entitled, "The Origin of Life on Earth," written by the Russian scientist, Aleksandr Ivanovich Oparin. He considered hydrogen, ammonia, water vapor, and methane to be components in the early atmosphere. Oxygen was lacking in this chemically-reducing environment. He stated that ultraviolet radiation from the Sun provided the energy for the transformation of these substances into organic molecules. Scientists today state that such spontaneous synthesis occurred only in the primitive environment. Abiogenesis became impossible when photosynthetic cells added oxygen to the atmosphere. The oxygen in the atmosphere gave rise to the ozone layer which then shielded Earth from ultraviolet radiation. Newer versions of this hypothesis contend that the primitive atmosphere also contained carbon monoxide, carbon dioxide, nitrogen, hydrogen sulfide, and hydrogen. Present-day volcanoes emit these substances.
In 1957, Stanley Miller and Harold Urey provided laboratory evidence that chemical evolution as described by Oparin could have occurred. Miller and Urey created an apparatus that simulated the primitive environment. They used a warmed flask of water for the ocean, and an atmosphere of water, hydrogen, ammonia and methane. Sparks discharged into the artificial atmosphere represented lightning. A condenser cooled the atmosphere, causing rain that returned water and dissolved compounds back to the simulated sea. When Miller and Urey analyzed the components of the solution after a week, they found various organic compounds had formed. These included some of the amino acids that compose the proteins of living things. Their results gave credence to the idea that simple substances in the warm primordial seas gave rise to the chemical building blocks of organisms.
In the second stage of chemical evolution, the simple organic molecules (such as amino acids) that formed and accumulated joined together into larger structures (such as proteins). The units linked to each other by the process of dehydration synthesis to form polymers. The problem is that the abiotic synthesis of polymers had to occur without the assistance of enzymes. In addition, these reactions give off water and would, therefore, not occur spontaneously in a watery environment. Sydney Fox of the University of Miami suggested that waves or rain in the primitive environment splashed organic monomers on fresh lava or hot rocks, which would have allowed polymers to form abiotically. When he tried to do this in his laboratory, Fox produced proteinoids—abiotically synthesized polypeptides.
The next step in chemical evolution suggests that polymers interacted with each other and organized into aggregates, known as protobionts. Protobionts are not capable of reproducing, but had other properties of living things. Scientists have successfully produced protobionts from organic molecules in the laboratory. In one study, proteinoids mixed with cool water assembled into droplets or microspheres that developed membranes on their surfaces. These are protobionts, with semipermeable and excitable membranes, similar to those found in cells.
In the final step of chemical evolution, protobionts developed the ability to reproduce and pass genetic information from one generation to the next. Some scientists theorize RNA to be the original hereditary molecule. Short polymers of RNA have been synthesized abiotically in the laboratory. In the 1980s, Thomas Cech and his associates at the University of Colorado at Boulder discovered that RNA molecules can function as enzymes in cells. This implies that RNA molecules could have replicated in prebiotic cells without the use of protein enzymes. Variations of RNA molecules could have been produced by mutations and by errors during replication. Natural selection, operating on the different RNAs would have brought about subsequent evolutionary development. This would have fostered the survival of RNA sequences best suited to environmental parameters, such as temperature and salt concentration. As the protobionts grew and split, their RNA was passed on to offspring. In time, a diversity of prokaryote cells came into existence. Under the influence of natural selection, the prokaryotes could have given rise to the vast variety of life on Earth.
See also Amino acid.
Resources
Books
Keeton, William T., and James L. Gould. Biological Science. New York: W.W. Norton and Co., 1993.
Periodicals
Franklin, Carl. "Did Life Have a Simple Start?" New Scientist (October 2, 1993).
Radetsky, Peter. "How Did Life Start?" Discover (November 1992).
Bernice Essenfeld
User Comments
12 months ago
Blair
Very interesting theory. It sounds very believable. Maybe in the future scientists will try to evolve protobionts into actual bacteria in long term experiments involving the primordial stew, lightning, and ultraviolet radiation for mutations.
about 1 month ago
ohhh this is nice ;)
3 months ago
Dov Henis
(Extend evolution way down to genes, life’s base ORGANISMS. Culture modifies genetics, not vice versa...)
Pavlov’s Smile: RNAs Are Earth’s Primal Organisms
Culture>genes>addiction (2 July 2009)
http://universe-life.com/2011/09/24/pavlovs-smile/
Why Pavlov smiled in 2008?
Pavlov demonstrated effecting placebo phenomena in multi celled organisms by manipulation of their drives-reactions. Now placebo and imagination phenomena are demonstrated also in Earth’s smallest, base organisms, in the genes and genomes of multi-celled organisms, in our primal 1st stratum and 2nd stratum base organisms.
A very good reason to smile.
Now an interesting chain is exposed to our view, the Genes-Virtual Reality Chain, a most intriguing cultural evolution chain extending from the genesis of our genes to nowadays, throughout life, a virtual reality existence, and by virtual reality phenomena, exploitations and manipulations.
Dov Henis (comments from 22nd century)
http://universe-life.com
Life Genesis From Aromaticity/H-Bonding
http://universe-life.com/2011/09/30/earthlife-genesis-from-aromaticityh-bonding/
10 months ago
good
10 months ago
1957, Stanley Miller and Harold Urey provided laboratory evidence that chemical evolution as described by Oparin could have occurred. Miller and Urey created an apparatus that simulated the primitive environment. They used a warmed flask of water for the ocean, and an atmosphere of water, hydrogen, ammonia and methane. Sparks discharged into the artificial atmosphere represented lightning. A condenser cooled the atmosphere, causing rain that returned water and dissolved compounds back to the simulated sea. When Miller and Urey analyzed the components of the solution after a week, they found various organic compounds had formed. These included some of the amino acids that compose the proteins of living things. Their results gave credence to the idea that simple substances in the warm primordial seas gave rise to the chemical building blocks of organisms.
Read more: Chemical Evolution - The primitive Earth - Atmosphere, Life, Water, Rna, Molecules, and Organic http://science.jrank.org/pages/1387/Chemical-Evolution.html#ixzz1KYjoJQjZ
12 months ago
Dov Henis
Suggested 2010 Updates Of Evolution Concepts
http://pulse.yahoo.com/_2SF3CJJM5OU6T27OC4MFQSDYEU/blog/articles/261519?listPage=index
http://pulse.yahoo.com/_2SF3CJJM5OU6T27OC4MFQSDYEU/blog/articles/261527?listPage=index
On The Nature And Origin Of Cosmic, Including Life, Evolution
Cosmic Evolution Beyond Darwin And Einstein
The purpose of OUR life and of its promotion is ours to formulate and set.
It derives solely from our cognition. Here is the nature and origin of
cosmic, including life, evolution.
Natural Selection Derives From Cosmic Expansion
http://www.the-scientist.com/community/user/profile/1655.page
"Evolution is energy temporarily constrained in a mass format to postpone reconversion of the mass to the energy fueling the cosmic expansion".
Two suggested editorial items:
I.
Origin And Nature Of Natural Selection
Update Concepts And Comprehension
Life is another mass format, a self-replicable format.
All mass formats are subject to natural selection.
Natural selection is delaying conversion of mass to energy fueling cosmic expansion.
Cosmic expansion is reconversion of all mass to energy.
Natural Selection Updated 2010
Beyond Historical Concepts
Natural Selection applies to ALL mass formats. Life, self-replicating format, is just one of them.
Natural Selection Defined:
> Natural selection is E (energy) temporarily constrained in an m (mass) format. Period. <
Natural selection is a ubiquitous property of each and every and all cosmic mass, spin array, formats. Mass strives to increase its constrained energy content in attempt to postpone its reconversion to energy and to postpone addition of its constitutional energy to the totality of the cosmic energy that keeps fueling the cosmic expansion going on since Big Bang.
Dov Henis
(Comments From The 22nd Century)
03.2010 Updated Life Manifest
http://www.the-scientist.com/community/posts/list/54.page#5065
Cosmic Evolution Simplified
http://www.the-scientist.com/community/posts/list/240/122.page#4427
Gravity Is The Monotheism Of The Cosmos
http://www.the-scientist.com/community/posts/list/260/122.page#4887
EOTOE, Embarrassingly obvious TOE, expanding the horizon beyond Darwin And Einstein
http://www.molecularfossils.com/2010/05/formal-test-of-theory-of-universal.html
********************************************************
Origin And Nature Of Natural Selection
Longevity Schmongevity Genes
It's Not The Procedure, But The Concept That Is Absurd
Longevity Genes Search Reflects Science Decadence
http://www.the-scientist.com/community/posts/list/320/122.page#6368
A. For most centenarians, longevity is written in the DNA.
A study of people who live past 100 reveals many genetic paths to a long life.
http://www.sciencenews.org/view/generic/id/60772/title/For_most_centenarians%2C_longevity_is_written_in_the_DNA
B. Longevity, survival, natural selection, evolution
- Merriam-Webster OnLine
Longevity = a : a long duration of individual life b : length of life
- Longevity is about survival, which is about "natural selection", which is about energy constrainment, which is about life evolution, which is about cosmic evolution. Every mass is destined to become energy to fuel the ongoing cosmic expansion. This is why organisms and black holes etc., eat, digest energy in mass forms, to avoid-postpone conversion to energy. This is evolution, which is natural selection, which is survival, which is longevity.
- All mass formats age. Life is a mass format. Searching for longevity genes is searching for evolution genes...
C. The search for longevity genes is a reflection of the 20th-21st centuries science decadence
Its concepts and terminology reflect the abandonment of basic science for adoption of the pretentious cancerous capitalist 20th-21st century technology culture.
Dov Henis
(Comments From The 22nd Century)
===========================================================
II.
Rethink Astronomy And The Universe
( even without Quantum Unique Ergodicity, but with plain commonsense )
Galactic clusters formed by dispersion, not by conglomeration. The proof of this is their behaviour, including acceleration, as Newtonian bodies.
These bodies formed at the start of inflation, when all energy was still in mass format, and the inflation was the start of reconversion of cosmic mass into energy. Cosmic expansion acceleration rate differs for each galactic cluster, proceeding according to Newton's laws, proportional to the various galactic clusters' masses.
Rethink
- A Basic Physics Tenet
- The Universe In Which We Live
A. Neutrino quick-change artist caught in the act
A transformation from one ‘flavor’ to another confirms the elusive elementary particles have mass and suggests a need for new physics.
http://www.sciencenews.org/view/generic/id/59825/title/Neutrino_quick-change_artist_caught_in_the_act
B. Adopt
- Each and every particle has mass.
- Dark energy and dark matter YOK. All universe energy and mass are plainly accounted for.
- Higgs field/particle YOK. Mass forms below some value of D in E=Total[m(1 + D)] .
- Do not be afraid of embarrassingly obvious answers. Adopt space-distance in lieu of space-time.
C. And Rethink The Universe
By the presently available data our universe is a dual-cycle array.
One cycle, the present, started from singularity, with all cosmic energy in mass format, and it has been proceeding to reconvert all the mass resolved at the big bang back to energy, by expanding the cosmos, by accelerating away the galaxy clusters.
The other cycle, the cycle leading to singularity, will re-start when the expanding cosmos consumes most or all mass that fuels the expansion. Gravity will then initiate reconversion of all the energy back to mass, to singularity, again.
Dov Henis
(Comments From The 22nd Century)
Dispel Some Figments Of 2010 Science Imagination
http://pulse.yahoo.com/_2SF3CJJM5OU6T27OC4MFQSDYEU/blog/articles/245540
03.2010 Updated Life Manifest
http://www.the-scientist.com/community/posts/list/54.page#5065
28Dec09 Updated "Implications Of E=Total[m(1 + D)] "
http://www.the-scientist.com/community/posts/list/180/122.page#3108
Evolution, Natural Selection, Derive From Cosmic Expansion
http://darwiniana.com/2010/09/05/the-question-reductionists-fear/
about 1 year ago
where from the oxygen came, is not clear to me.