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Is abiogenesis possible today?

Is abiogenesis possible today?


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Life on earth started about 3.5 billion years ago. I would assume abiogenesis happened because the conditions were right.

Would the current earth conditions allow for new abiogenesis and completely independent (in terms of phylogeny, not ecology)?


I will argue that yes, it is POSSIBLE. It is possible on earth like on other planets. Given enough time, matter, and energy, "something" that resembles life will emerge. The problem I see, however, is that life has already conquered our planet, so any "new living thing" will have to compete with other long-time adapted living thing, in practice, no chance of survival. The right conditions you refer to are the ones that allowed "life as we know it" to emerge. Given other conditions (other chemicals, other energy forms, etc), something completely different will form.

Of course, without final proves, this is still speculation.

Some speculative links:

http://speculativeevolution.wikia.com/wiki/Alternative_biochemistry

http://www.dailygalaxy.com/my_weblog/2015/05/alien-life-habitats-nasa-brainstorms-alternatives-to-water.html

http://www.nature.com/news/2009/090513/full/news.2009.471.html


Abiogenesis

Abiogenesis is the creation of organic molecules by forces other than living organisms. While organisms can create carbon-carbon bonds relatively easily thanks to enzymes, to do so otherwise requires large inputs of energy. Early in the history of science, this fact was used to dispute evolution, as it could not be conceived how organic molecules could be produced from non-organic sources. The theory of abiogenesis as an evolutionary theory was given much credit when Stanley Miller conducted his famous experiment trying to prove the inorganic beginning of life.

Miller combined various gases that were though to exist in the earliest stages of Earth. These gases were combined in a chamber, and shocked with large amount of electricity for weeks at a time. After the trial, Miller would analyze the samples. He found that the molecules had begun the process of combining into more advanced molecules. Miller theorized that over billions of years, these molecules could combine into self-replicating versions, such as RNA and DNA. Further laboratory experiments confirmed these findings in later decades. Several very precise experiments have provided sufficient evidence that many of the molecular structures of cells could be created from inorganic solutions with an input of energy. Polypeptides (proteins) and RNA have both been synthesized in this way.

The synthesis of both proteins and RNA in the laboratory is a crucial piece of evidence for abiogenesis theory. It is though that the abiogenesis of these molecules could lead to self-replicating RNA molecules. Both proteins and RNA molecules are known to act as catalysts. These molecules, produced by abiogenesis, could catalyze important reactions that could lead to the replication of RNA and the production of complexes such as ribosome, which translate proteins from RNA messages. The formation of these two molecules through abiogenesis proves that the first steps in abiogenesis theory could have taken place. Due to the large amount of energy used, some scientists argue that abiogenesis theory does not consider the amount of lightning and other energy sources in the early atmosphere.


Abiogenesis

Even before the time of the ancient Greeks, people thought that mice came from straw, that rotting meat would transform directly into flies, and that fleas were created from sand. Spontaneous generation is the term that was used to describe the creation of life in this way. The Greek scientist and philosopher Aristotle (384-322 BCE) was one of the earliest scientists to describe a theory for abiogenesis, in which all life arose directly from different combinations of earth, wind, fire and water. Although abiogenesis has never been observed in the lab, some mechanism involving it was likely involved in creating the simpler molecules (lipids, carbohydrates, proteins, etc.) that were part of the beginning of life on Earth. One of the challenges in developing scientific models around abiogenesis is explaining how molecules formed into cells which became self-replicating. One theory involves protocells, which are organized collections of lipids that form into a spherical shape.


Abiogenesis

Abiogenesis Meaning- The formation of organic molecules by factors other than living organisms is known as abiogenesis. Although enzymes make it relatively easy for organisms to form carbon-carbon bonds, doing so without them takes a lot of energy. This fact was used to refute evolution early in the history of science because it could not be imagined how organic molecules could be formed from non-organic sources. When Stanley Miller performed his famous experiment to prove the inorganic beginning of existence, he gave a lot of credit to the theory of abiogenesis as an evolutionary theory.

Miller combined a variety of gases that were thought to exist in Earth's early stages. These gases were mixed in a chamber and shocked for weeks at a time with a huge amount of electricity. Miller would examine the samples after the trial. He discovered that the molecules had started to combine to form more complex molecules. Miller theorised that these molecules could combine over billions of years to form self-replicating versions like RNA and DNA. In later decades, further experimental studies backed up these results.

Many of the molecular structures of cells could be produced from inorganic solutions with the addition of energy, according to several very precise experiments. This method has been used to make polypeptides (proteins) and RNA.

The ability to synthesise proteins and RNA in the lab is critical evidence for the abiogenesis theory. It's possible that these molecules' abiogenesis will result in self-replicating RNA molecules. Catalysts are known to exist in both proteins and RNA molecules. These molecules, which are formed during abiogenesis, could catalyse important reactions such as RNA replication and the formation of complexes like the ribosome, which translate RNA messages into proteins. The abiogenesis development of these two molecules demonstrates that the first steps in abiogenesis theory may have occurred.

What is Abiogenesis Theory and Why is it Important?

The Abiogenesis theory states that all life began as inorganic molecules that recombined in various forms as a result of energy input. These various forms gradually coalesced into a self-replicating molecule, which may have used the other molecules created by abiogenesis to begin forming life's fundamental structures, such as the cell.

In the same way, as populations evolve over time in the evolution of animals, molecules change over time in the evolution of molecules. Scientists believe that RNA molecules were the first self-replicating molecules. As seen in the ribosomes of nearly all living things on Earth, certain RNA molecules have the ability to catalyse the formation of new RNA molecules. One of these early RNA molecules shaped in such a way that it created an identical RNA molecule. Via abiogenesis, the concentration of this molecule in the prebiotic soup increased dramatically, and the molecule interacted with itself and some proteins developed around it.

Eventually, mutations in the RNA molecule enabled it to synthesise a protein that produced more RNA. Other mutations resulted in the development of proteins that synthesised DNA strands from RNA. As a result, the modern organism's genome was born. Changes in these molecules steadily evolved through millions of years of evolutionary history, resulting in the complexity of life we see today. Various scientists who research abiogenesis theory disagree about when abiogenesis transitions to biogenesis. In the debate about whether or not viruses are living beings, similar claims can be found. Hence, Abiogenesis meaning can be summed up as a process of creating organic molecules from inorganic molecules.

Abiogenesis Theory- Experimental Basis

Stanley Miller, an American graduate student, and Harold Urey, his graduate advisor, agreed to test the Oparin-Haldane abiogenesis hypothesis by recreating an early Earth system in the early 1950s. They discharged sparks from the mixture after mixing the basic compounds and elements from the theory in the air.

They were able to detect amino acids produced during the simulation by analysing the chemical reaction products. Later experiments attempting to establish replicating molecules from amino acids were confirmed by this proof that the first part of the theory was right. These experiments were a failure.

Following the Miller-Urey experiment, researchers discovered that the prebiotic atmosphere of early Earth contained more oxygen and fewer other essential substances than the sample used in the experiment. This made people wonder if the conclusions were still true.

Since then, studies using a corrected atmosphere composition have discovered organic molecules including amino acids, confirming the initial findings.


The Origins of the Universe

Another related error made by some creationists is the idea that evolutionary theory cannot explain the origin of the universe while creationism does. Once again, this is used to explain how evolution is inferior to creationism.

However, the origins of the universe are even further removed from evolutionary theory than is the origin of life. There is some connection in that scientists seek naturalistic explanations for both. That is simply due to the fact that they are both scientific pursuits. It is not because of any inherent relationship such that problems with one will undermine the other.


Abiogenesis Is Impossible

This round is for acceptance, definitions, and rules only.

Abiogenesis:
"The supposed *spontaneous* development of living organisms from nonliving matter. Also called autogenesis, spontaneous generation."-The American Heritage® Dictionary of the English Language

(Emphasis on spontaneous added so as to avoid a debate on semantics. This keeps in line with the original definition since "abiogenesis" can also be called "spontaneous generation" as given by the dictionary)

Rules : This debate will be about what science has already discovered. Neither side can appeal to a negative. For example:

Pro can not use the argument "Science does not know how X could exist, therefore X did not exist"

Likewise, Con can not use the argument "Science has discovered many things. Therefore, in the future scientists will discover how X could exist, therefore X existed"

The resolution will be whether or not abiogenesis is possible based on current discoveries and scientific knowledge.

As Pro, my position will be to prove that all (presented) findings regarding abiogenesis either rely on irrelevant scenarios (such as scenarios where certain chemicals that have been proven to have existed billions of years ago are ignored), or produce findings that actually support my resolution that abiogenesis is impossible.

Since the rules are to avoid appealing to a negative, this debate will officially begin once Con has made his opening arguments. However, I would like to get one thing out of the way first:

I. Problems with the Miller-Urey Experiment.

1. Ignored the presence of oxygen.

The Miller-Urey experiment utilized the gases methane, ammonia, and hydrogen. However, it ignores the presence of oxygen, which has been proven to exist for 4.3 billion years. [1] When it comes to biosynthesis, "laboratory experiments show that chemical evolution, as accounted for by present models, would be largely inhibited by oxygen". [2] That is to say, oxygen would have destroyed many of the organic molecules created in any sort reducing atmosphere.

2. Produced only small amounts of amino acids.

The Miller-Urey experiment, while producing more then the 20 amino acids required for life, only produced small yields of these amino acids. The most common amino acids formed were glycine and alanine. Yet glycine made up only 1.05% of the total yield, and alanine only 0.75%. [3]

3. Non-existent methane-ammonia atmosphere.

". the accepted picture of the earth&rsquos early atmosphere has changed: It was probably O2-rich with some nitrogen, a less reactive mixture than Miller&rsquos, or it might have been composed largely of carbon dioxide, which would greatly deter the development of organic compounds."-[4]

Since volcanoes only release carbon monoxide, carbon dioxide, nitrogen, and water vapor, it is now believed by scientists that methane, ammonia, and hydrogen did not make up the majority of early earth's atmosphere [5]. This is also why scientists do not believe that an early atmosphere played a huge part in chemical evolution. [6]

4. Amino acids were produced in racemic mix. [7]

Amino acids synthesize in both right-handed and left-handed versions. The amino acids required for life are all left-handed (with only rare exceptions), and the sugars required for life are all (with only rare exceptions) right-handed. Any protein that utilizes a right-handed amino acid is rendered useless for life. All experiments to remedy this problem have failed. [8]

There are various problems with this hypothesis. My favorites being problems with cytosine and ribose, and in addition, a lack of a process to polymerize RNA strands. However, rather then list them all (there are quite a few), I'm going to allow my opponent to make his case and then list any problems relevant to his case.

[1] Bortman, H. 2001. Life Under Bombardment (http://nai.nasa.gov. ) from the NASA Astrobiology Institute. - Alternating layers of oxidized iron in the so-called banded iron formation from Akilia Island in West Greenland demonstrates that free oxygen has been present on earth longer than 3.85 billion years.

Carver, J. H. 1981. Prebiotic atmospheric oxygen levels. Nature 292: 136-138 (http://www.nature.com. ).

Ohmoto H., Y. Watanabe, H. Ikemi, S.R. Poulson, B.E. Taylor. 2006. Sulphur isotope evidence for an oxic Achaean atmosphere. Nature 442:873-874. (http://www.ncbi.nlm.nih.gov. )

Dustin Trail, D., E. B. Watson and N. D. Tailby. 2011. The oxidation state of Hadean magmas and implications for early Earth&rsquos atmosphere. Nature doi:10.1038/nature10655. (http://www.nature.com. )

[2] Flowers, C., A Science Odyssey: 100 Years of Discovery, William Morrow and Company, New York, p. 173, 1998.

[3] Shapiro, R., Origins A Skeptics Guide to the Creation of Life on earth , Summit Books, New York, p. 99, 1986.

[4] Flowers, C., A Science Odyssey: 100 Years of Discovery , William Morrow and Company, New York, p. 173, 1998.

[8] Sarfati, J., Origin of life and the homochirality problem: is magnetochiral dichroism the solution? TJ14 (3)9&ndash12, 2000.

Before I defend Abiogenesis, I am going to give a brief rundown regarding how life formed on the early earth.

What is Abiogenesis?
__________________

The early pre-biotic earth was filled with organic molecules (which are quite common in space), the building blocks of life. The pre-biotic environment contained many simple fatty acids, under a range of PH they spontaneously form stable vesicles. With naturally occurring simple fatty acids, we can have a vesicle that can spontaneously grow from consumption and divide. The pre-biotic environment contained hundreds of different types of nucleotides, all it took was one to polymerize, they can replicate themselves.

So far we have lipid vesicles that can grow and divide, and nucleotide polymers that can self-replicate all on their own, but how does it become life? Well fatty acid vesicles are permeable to nucleotide monomers, but not polymers. Once polymerization occurs within the vesicle, the polymer gets trapped! In the ocean they will encounter convection currents. A vesicle with more polymer, through simple thermodynamics will steal lipids from a vesicle with less polymer, this is the origin of competition. A Vesicle that contains polymer can replicate, grow and divide faster therefore dominating the population. Self-polymerizing molecules will kick off evolution, and we see things like complex sexual reproduction arise, basically where the fun begins )

What about intelligence?
_____________________

First we have to define intelligence, I mean is intelligence the ability to learn and make choices? Well it may shock you than even bacteria can do both of those things. A species of bacteria rapidly evolved, selecting for a single nucleotide insertion, forming a new gene which allowed it to digest nilon, this is just one example of how evolution can increase information stored in DNA. The bacteria learn how to digest the nilon. Of course a bacteria's intelligence pales in comparison to our own, so how did something as complex as the brain arise? Well our brains have 100 billon neurons and 1 quintillion synapses. A neuron is simply a cell which transfers electrical impulses form one location to another. Now DNA sequences reveal that ion channels used in the neurons in animals had their origin in bacteria. The first neurons were simply coopted, bacterial ion channels, put to the new task of transferring information. As multi celled organisms form they need a way to rapidly transmit information and form brains because they can produce the ability to transfer information faster and over longer distances than simple passive waves which are not up for the task.

Refuting my opponent's criticisms on the Miller-Urey experiment
_____________________________________________________

Lets say I granted him the notion that the Miller-Urey experiment was not valid, this still wouldn't even put a dent in the fact that Abiogenesis is at least possible simply based off one experiment being invalid. Since I am not granting him that notion, here is my response to some (I don't have enough room to refute all) of his objections to the experiment.

" …it ignores the presence of oxygen, which has been proven to exist for 4.3 billion years"

This is absolutely off (by 2 billion years)

Oxygen did not exist in the early atmosphere. Early life took in carbon dioxide and sunlight, exhaling oxygen as a waste gas. After a few million years, this waste gas became a significant part of the atmosphere, enough so that new opportunistic species could use it for respiration. The reason why my opponent is mistaken is because plants (life) are what produce oxygen in the air, therefore oxygen must not have been present when the earliest life formed.
Animals need oxygen. "You cannot evolve animals like us without having a significant amount of oxygen," says geochemist Dick Holland of Harvard University. "Without the Great Oxidation Event [a dramatic rise of oxygen in Earth's atmosphere some 2.3 billion years ago], we would not be here. No dinosaurs, no fish, no snakes - just a lot of microorganisms."

"The Miller-Urey experiment, while producing more than the 20 amino acids required for life, only produced small yields of these amino acids."

This point is moot. The very fact that these amino acids were produced speaks volumes on the success of the experiment and the possibility of Abiogenesis. Miller's experiment showed that organic compounds such as amino acids, which are essential to cellular life, could be made easily under the conditions that scientists believed to be present on the early earth.

"Since volcanoes only release carbon monoxide, carbon dioxide, nitrogen, and water vapor.."

Volcanic eruptions involve the release of methane, ammonia, and hydrogen gases as well as water vapor (http://ua-ib-bio.tumblr.com. ).

My case in favor of Abiogenesis being possible
_______________________________________

1) The very fact that all people who do not advocate Abiogenesis throw out how the probability of it is so low, proves that even they believe it is possible. If they didn't, they would say the chance of it happening is 0.

2) The fact we are here proves not only is it possible, but it most likely happened (unless you believe in the supernatural and magic)

Scientific case:
_____________

Primordial Soup—Miller-Urey use a mix of methane, ammonia, and hydrogen to form basic amino acids in the lab.

Deep Sea Vent Theory—Hydrogen saturated, heated, fluids from hydrothermal vents on the ocean floor mix with carbon dioxide laden water. Continued chemical energy from the interactions sustains processes that produce simple organic molecules.

Spontaneous Formation of Small Peptides from Amino Acids: Sidney Fox demonstrated that the conversions could occur on their own.

Eigen's hypothesis—Eigen and Schuster argue that some molecules, possibly RNA, can serve as an information storing system that brings about the formation of other information storing systems, or a kind of replication.

Radioactive beach hypothesis: radioactive elements such as uranium may have concentrated on beaches and become building blocks for life by energizing amino acids, sugars from acetronitrile in water.

Homochirality: The right or left handedness of organic molecules may be explained by the origin of compounds in space.
Self-organization and replication: Under the right circumstances, many non-organic molecules exhibit properties of self-organization and self-replication.

"Genes first" models: the RNA world It has been argued that short RNA molecules could have formed on their own. Cell membranes could have formed from protein-like molecules in heated water. Chemical reactions in clay or on pyrites could have initiated self-replication.

"Metabolism first" models: iron-sulfur world and others. Some theories argue that metabolic processes started first, then self-replication.

Bubbles collecting on the beach could have played a role in forming early, proto-cell membranes.

Autocatalysis Some substances catalyze the production of themselves such as amino adenosine, pentafluorophenyl ester, and amino adenosine triacid ester.

Clay theory Complex organic molecules could have arisen from non-organic replicators such as silicate crystals. It has even been reported that the crystals can transfer information from mother to daughter crystals.

Gold's "Deep-hot biosphere" model Gold argues that life originated miles below the surface of the earth. Microbial life has been found there, and it may be present in other plants.

"Primitive" extraterrestrial life Organic compounds are common in space, and early life may have been transferred here from other planets such as Mars.

Additional Sources:
________________

I thank my opponent for a speedy reply!

First off, I'd like to point out that while Con has skillfully outlined for us the hypothesis of abiogenesis, he has neither offered evidence to support the hypothesis nor cited sources that offer evidence to support it.The youtube video he offers, while having a wonderful classical instrumental played in the background, also fails to offer evidence to back up its claims or cite sources.

Not only that, but there are fundamental problems with Con's introduction of abiogenesis:

1. "The early pre-biotic earth was filled with organic molecules"

What proof does Con have that the pre-biotic earth was filled? Experiments to produce organic molecules often only given small yields of organic molecules. The Miller-Urey experiment only gave a yeild of 2%. That coupled with the destructive nature of oxygen [see sources in round 1], how could the pre-biotic earth have been filled with organic molecules? Also, what specific organic molecules? Amino acids are not the only building blocks for life. RNA and DNA strands alone require nucleotides, phospates, sugars. There are other problems, but I only have so much space.

2. "The pre-biotic environment contained hundreds of different types of nucleotides, all it took was one to polymerize, they can replicate themselves."

"Hundreds of different types of nucleotides". I find this strange, seeing as how there are only five (plus, two recently discovered cell-modified versions of cytosine) types of nucleotides known to exist: Cytosine, uracil, adenine, guanine, and thymine. What proof does Con have that these nucleotides even existed. Are there a few hundred other types of nucleotides that Con has discovered that we don't know about?

Also, the phrase "all it took was one to polymerize" is deceptive. First of all, a single nucleotide can not polymerize. Polymerization is the process in which one molecule bonds with another molecule. It would take multiple nucleotides for polymerization. Also, polymerization of nucleotides is tricky because a nucleotide base pair actually consists of not only two nucleotides but a phosphate and a sugar (in RNA, it's ribose. In DNA, it's deoxyribose), in addition, because molecules can bond with a plethora of different chemicals in a plethora of different ways, Con needs to show a way in which these chemicals could have bonded correctly, either without the use of ATP and the enzymes modern cells use to catalyze and control the polymerization process, or he must show that ATP and enzymes could have existed.

Note: Adenine and guanine have been produced in abiogenesis experiments (there are problems with these experiments, but I'm trying to only give relevant rebuttals) and have been discovered in meteorites. Uracil can be produced from pyrimidines, but cytosine has not been produced in spark experiments. There is an experiment that involves combining two cytosine derivates (created in small ammounts from spark experiments). However, I'll only give the problems to this experiment if Con cites it as evidence that cytosine could have existed.

3. "So far we have lipid vesicles that can grow and divide, and nucleotide polymers that can self-replicate all on their own"

Wait a second, we have nucleotide polymers? When did this happen? It seems that our opponent has sadly forgotten to cite evidence, once again.

Note: Even if nucleotide polymers were to have existed, when RNA self-replicates, it actually replicates onto itself, and becomes closed like a zipper. In modern day cells, the enzyme polymerase is produced to unzip this "zipper".

4. "The pre-biotic environment contained many simple fatty acids, under a range of PH they spontaneously form stable vesicles."

I'm actually not going to focus on the problems with this statement. However, this site gives a detailed list of issues with the genesis of a cell membrane, if the audience is interested in looking into it:

Refutations Of Con's Refutations

1. "This is absolutely off (by 2 billion years)"

Con assumes that oxygen can only be produced by organisms (this is false, oxygen can exist without organisms creating it. Not only that, but oxygen has been found in space, where there aren't any organisms [1]), and ignores the evidence in the oxidized iron from Akilia Island in West Greenland as well as the evidence from the other three sources I cited.

2. "Volcanic eruptions involve the release of methane, ammonia, and hydrogen gases as well as water vapor"

Con cited a tumblr post with an unknown author that itself does not cite any sources. I can find no other sources that back up his claim. Unless Con can find another source to back up his claim, please consider his point null and void.

3. "The very fact that all people who do not advocate Abiogenesis throw out how the probability of it is so low, proves that even they believe it is possible. If they didn't, they would say the chance of it happening is 0."

Obviously I consider the probability of abiogenesis taking place to be 0. Otherwise I wouldn't be debating you right now.

4. "The fact we are here proves not only is it possible, but it most likely happened (unless you believe in the supernatural and magic)"

Con refutes his own claim. There are many who believe in the supernatural. It has also not been proven that the supernatural doesn't exist.

5. Here Con gives a long list of hypotheses. The question is: Which of these does Con advocate? Where is the evidence to back up these hypotheses?

The existence of a hypothesis about how something could have happened does not prove that it did or can happen.

I'd like to make a note of the sources Con has used in his argument.

Source 1: A youtube video that "summarizes" a particular scientists work yet fails to cite any sources, and skips over the fundamental problems with abiogenesis as listed in above arguments.

Source 2: An alleged quote from a particular geochemist.

Source 3: A tumblr post with an unknown author and un-cited content.

Source 4: A faulty link to some unknown blogspot post.

Source 5: A website that describes the Miller-Urey experiment.

Can you spot the evidence for abiogenesis? Neither can I.

"he has neither offered evidence to support the hypothesis nor cited sources that offer evidence to support it"

I will site more this round if I see fit but saying I never sited sources isn't really a factual statement.

My opponent is speaking about Abiogenesis in a tone that implies the debate is whether it happened or not, not whether or not it is possible. This is a point I really want to stress in this debate, because so far all Pro has done is try to discredit one experiment and has not made a single point indicating how Abiogenesis is impossible.

People who reject Abiogenesis will claim:

"The formation of any enzyme by chance is nearly impossible, therefore abiogenesis is impossible"

A calculation from the astrophysicist Fred Hoyle named "Borel's Law" was created with the intent to show that Abiogenesis is statistically impossible.

The problems with calculations like these?
__________________________________

1) They calculate the chance of a"modern" protein forming, or even a complete bacterium with all "modern" proteins, by strictly random events. This is not what Abiogenesis hypothesizes at all.

2) They make the assumption that there is a fixed number of proteins, with fixed sequences for each and every protein that are required for life to form.

3) They only calculate the probability of sequential trials and not simultaneous trials.

4) They underestimate the number of functional enzymes/ribozymes existing in a group of random sequences.

The calculation states that the probability of forming a 300 amino acid long protein (an enzyme like carboxypeptidase) randomly is (1/20)300 or 1 chance in 2.04 x 10390. One of the flaws is that the formation of biological polymers from monomers is a function of the laws of chemistry and biochemistry, and these are not random by any stretch of the imagination, contrary to what the calculation assumes. Another major flaw is the fact that the entire premise is incorrect to start off with, because in modern abiogenesis theories the first "living things" would be much simpler, not even a protobacteria, or a preprotobacteria, rather one or more simple molecules probably not more than 30-40 subunits long.

How is Abiogenesis possible

The theory is that you go from simple chemicals, to polymers, to replicating polymers, to a hypercycle, to protobiont system, and finally to bacteria.

I am going to explain how this is in fact, possible:

A monomer (from Greek mono "one" and meros "part") is an atom or a small molecule that may bind chemically to other monomers to form a polymer. A polymer is a large molecule (macromolecule) composed of repeating structural units. These subunits are typically connected by covalent chemical bonds (http://en.wikipedia.org. ). The repeating structural unit of most simple polymers not only reflects the monomer(s) from which the polymers are constructed, but also provides a concise means for drawing structures to represent these macromolecules. For polyethylene, arguably the simplest polymer, ethylene (ethene) is the monomer, and the corresponding linear polymer is called high-density polyethylene (HDPE). HDPE is composed of macromolecules in which n ranges from 10,000 to 100,000 (molecular weight 2*105 to 3 *106 ) (http://www.talkorigins.org. ).

The subunits of polymers are held together by chemical compounds, therefore providing evidence that it is possible to go from chemicals to polymers.

An accurate mathematical model concerning the origin and the growth of self-replicating polymers has been developed. The polymers compete for activated monomers which can be carried into the system under constant or periodic fluxes. Changes in their concentrations are determined by spontaneous generation of the shortest polymers, ligation with free monomers at the end of their chains, template-instructed synthesis for polymers above a length threshold, and decomposition (http://www.sciencedirect.com. ).

The competition between polymers for activated monomers can kick off the process of replication.

A Hypercycle is a new level of organization where self-replicative units are connected in a autocatalytic manner. The self-replicative units are themselves catalytic cycles (http://www.enotes.com. (chemistry)).

Since replicating polymers are self-replicating units, then it's possible for them to engage in this new level of organization.

Theoretical treatments of hypercycles show that, once evolved from RNA, DNA will take over as the master molecule by virtue of it's storage capacity. Once DNA merged as the master hereditary molecule, the length of it's nucleotide strands could be increased, spelling out the alphabet of base pairs containing the information required for the machinery of life. Protobionts form spontaneously in the laboratory under a variety of different hypothetical early Earth conditions.(http://books.google.ca. )

Treatments of hypercycles indicate that DNA will take over as the master molecule, and protobionts form spontaneously under a wide range of theorized early earth conditions.

The earliest mitochondria could be used as food by other protobionts, but some of them could not be processed as food, but survived living as symbionts into more complex protobionts. Progressively, the functional relationship would be more vital for both mitochondria and protobionts, until they could not omit one to another. This indicates the process of the origin of the first prokaryotic heterotrophic protists (e.g. Archaea and Bacteria) (http://www.biocab.org. ).

So, I have shown that is it possible to gets from simple chemicals, to polymers, to replicating polymers, to a hypercycle, to protobionts, and to heterotrophic protists.

Abiogenesis is indeed possible.

Quick response to the errors in Pro's objections

Regarding when oxygen appeared on earth
___________________________________

Pro tried to combat my rebuttal about his error about how many years ago Oxygen appeared on earth, I will point out his huge error once again.

NASA-funded astrobiologist researchers report that traces of oxygen appeared in Earth's atmosphere from 50 to 100 million years before what is known as the Great Oxidation Event. This event happened between 2.3 and 2.4 billion years ago, when many scientists think atmospheric oxygen increased significantly from the existing very low levels 50 to 100 million years before that (http://www.nasa.gov. ).

Regarding volcanoes
_________________

The Earth's surface was originally molten, as it cooled the volcanoes belched out massive amounts of carbon dioxide, steam, ammonia and methane (http://www.moorlandschool.co.uk. ).

A cryovolcano is a volcano that erupts volatiles such as water, ammonia or methane. (http://en.wikipedia.org. ). I am mentioning this type of volcano not seen on Earth, is because it's effects are somewhat similar to the volcanoes that erupted on the Earth's surface after it cooled.

a) Pro has only attempted to poke holes in one experiment, and has not met his burden of proof in regards to Abiogenesis being impossible.

b) Abiogenesis is a process involving multiple steps, I have met my burden of proof in regards to proving these steps are at least possible.

c) Pro has made errors in regards to things like the ammonia and methane, and oxygen in the early Earth ect.

. I have met my burden of proof regarding the possibility of Abiogenesis

. My opponent has not demonstrated how Abiogenesis is impossible.

"saying I never sited sources isn't really a factual statement."

Con is right, this is why I never claimed Con failed to cite sources. But that he failed to cite evidence, or sources that themselves cited sources with evidence for abiogenesis.

On Con's Video Source

While the video Con cited is a little closer to the sort of evidence Con needs to prove abiogenesis is possible, it fails to answer a few of my objections:

1) Where did we get all of the nucleotides? Con has yet to provide a reasonable mechanism to produce all the neccessary nucleotides.

2) How did the original polynucleotide polymerize? Even the scientist in Con's video admits at 3:50 that he (and, presumably, his crew) have no accurate models for how this would could take place, as well as how the entire self-replication process could take place.

3) Where did we get the ribose and phosphates necessary for nucleotide polymerization? Ribose is created in modern day cells by enzymes. But enzymes wouldn't have existed in a primordial earth, leaving us with a chicken-or-egg scenario. Con must show (and prove) how either (a) ribose can be made without enzymes (b) enzymes could have spontaneously came into existed without RNA or DNA or (c) RNA or DNA can be made without ribose.

Con's argument is a good one, and probably could have helped him win this debate if it were relevant. Unfortunately for him, I am not arguing that abiogenesis is impossible because it has a low probability. I am arguing it is impossible becuse there are impenetrable barriers in the paths to chemical evolution. Thus his argument is irrelevant, and fails.

How Con Has Not Shown That Abiogenesis Is Possible

For one, everything Con posted is almost completely copied and pasted from the sources Con cited. Two, Con has oversimplified abiogenesis, probably hoping that the complex language he used would cover up for his lack of evidence, allow me to explain:

First Con describes how monomers polymerize into polymers. This is wonderful, were this debate about whether polymers could come about spontaneously or not. I am not arguing that spontaneous polymerization is impossible. I am arguing that spontaneous polymerization of amino acids and nucleotides is impossible. This is important to note. Con makes the mistake of assuming that because ethylene, which is not even an amino acid, can polymerize spontaneously, that all amino acids and nucleotides could have polymerized spontaneously. Since ethylene isn't even an amino acid, his evidence is irrelevant and thus, void.

This mistake alone would be enough to dismiss the rest of Con's argument, but since I have 5,379 characters left, I shall continue.

Secondly, this paragraph is also irrelevant, since we are discussing proteins and polynucleotides, not polymers in general. Also, what is this "accurate mathmatical model"? What does it look like? Who created it? How was it created? How has it been proven to be "accurate"? Is it accurate in theory, or accurate once applied to experiments. Surely if an accurate model existed about how self-replicating polymers actually existed, it would have blown up the headlines. In addition, this is from Con's source:

" In this first analysis of the model, we are supposing that primordial competition occurred among short self-replicating homopolymers. The dynamics of this population is investigated by computer simulations."-http://www.sciencedirect.com.

Here we see that (A) the scientists who have made this "accurate" model are making unproven assumptions. and (B) are using computer simulations to justify there experiments. I think it is self-evident that computer simulations (based on biased and unproven assumptions) can not be relied upon as "accurate" evidence, or even to give an "accurate" model.

In regards to hypercycles, Con's link didn't work, thus I honestly can't give a rebuttal. Con is a bit vague though. What is a hypercycle exactly? What "self-replicating" units is Con discussing, exactly?

"Theoretical treatments of hypercycles show that, once evolved from RNA, DNA will take over as the master molecule by virtue of it's storage capacity"

Theoretical treatments of anything do not constitute evidence. Theoretically, anything is possible, if you have a theory that allows it to be possible.

Thus follows the rest of Con's "proof" that abiogenesis is possible. All Con has proved is that abiogenesis is possible in theory. Con has not proved that abiogenesis is possible in reality.

Abiogenesis, is not possible. Because:

A) Neccessary ingrediants for abiogenesis would not have existed (cytosine, amino acids only made in methane-ammonia chemical reactions, ribose, etc.)

B) These ingrediants could not have spontaneously polymerized.

There are other reasons, but since this is the last round it doesn't make sense to address new problems.

Refutations

Interestingly, this other article from NASA actually corrects Con's and Con's source's view. Showing that evidence in iron banding reveals that oxygen has been present for over 3.85 billion years:
http://nai.nasa.gov.

On Methane-Ammonia Atmosphere

Con cites a volcano that has never been found on earth, and gives no proof that this sort of volcano ever existed on earth. Thus his rebuttal should be considered null and void.

a) I have clearly shown that according to current scientific research, we can conclude that abiogenesis is impossible.

b) I have clearly met my burden of proof that many of the steps required for abiogenesis could not have taken place.

c) Con made errors in regards to assuming there was methane an ammonia on the earth based on a volcano that did not exist on earth, and gave no relevant rebuttal to the evidence I cited that oxygen has been present on the earth for over 3.8 billion years.

I have demonstrated how abiogenesis is impossible, my opponent has neither cited evidence how it is, or given anything but an ambiguous explanation about how it is possible.

Problem with Pro's arguments

It seems that my opponent assumes that making the claim that I haven't shown how Abiogenesis is possible, is somehow also making a case for how Abiogenesis is impossible.

Attempting to poke holes in arguments is only one aspect of the debate, the most important part is making an argument of your own.

Regardless, I will defend aspects of the video (which wasn't even really a major part of my argument, just something that I felt wouldn't hurt to be included for people interested on the subject for the most part).

Answers to questions raised by Pro

"Where did we get all of the nucleotides?"

The first step of nucleotide synthesis is the formation of a nucleotide which is the nitrogenous base joined to a sugar. The sugar involved in the synthesis and structure of a nucleotide may be either ribose or deoxyribose in the latter case, the prefix 'deoxy' may be added before the name of the nucleoside in all cases except Uracil.

A functional group of phosphate is then esterified to the sugar, creating a nucleotide. The phosphate group may consist of one, two, or three phosphates, forming monophosphates, diphosphates, or triphosphates, respectively.

This is where we get nucleotides from.

"How did the original polynucleotide polymerize?"

The first one simply chained to the next.

Nucleotides get chained together like other biological molecules, by a condensation reaction that releases a stable molecule. Unlike carbohydrates, proteins, and lipids, the molecule that get's released is pyrophosphate not water.

When pyrophosphate is cleaved after the watter is added a massive amount of free energy is released making sure that the reverse process most likely does not happen.

"enzymes wouldn't have existed in a primordial earth"

A study at the Georgia Tech School of Biology found that a group of ancient enzymes known as thioredoxin were chemically stable at temperatures up to 58 degrees Fahrenheit higher than their modern counterparts.
The enzymes, which were around four billion years old also showed increased activity at lower pH levels, which correspond to greater acidity.
.http://www.sciencedaily.com.

Refutation of Pro's baseless claim that Abiogenesis is impossible

"Abiogenesis, is not possible. Because:

A) Neccessary ingrediants for abiogenesis would not have existed (cytosine, amino acids only made in methane-ammonia chemical reactions, ribose, etc.)"

B) These ingrediants could not have spontaneously polymerized."

A) I already provided a source for the study which proves that enzymes existed over four billion years ago. Also, the early atmosphere was different. Volcanoes helped create the warm Earth with their eruptions which shot a mix of water vapor, carbon monoxide, carbon dioxide, hydrochloric acid, methane, ammonia, nitrogen, & sulfur gases into the atmosphere.

B) You have provided no evidence that these ingredients could not have spontaneously polymerized, this is just a baseless assertion on your behalf. I have provided arguments and sources regarding how the ingredients polymerized.

Abiogenesis is definitely possible, as a scientist you have to assume this is what happened. First of all, don't confuse abiogenesis with spontaneous generation, abiogenesis was a gradual process that took millions of years.

How exactly it happened we will never know, after all, no one was there to see it. What scientists can do is provide a possible explanation.

Basically say: "look, I can prove this way was physically possible, and since life had to come about at some point this is most likely how it happened".

Even if one way has criticisms of it that doesn't mean that all ways of Abiogenesis happening are impossible.

. My opponent has provided not evidence that the right combination of chemicals combining cannot produce the building blocks of life.

. Pro also has attempted to poke many holes in my arguments but did a very poor job of making a solid argument for himself in his favor.

. I have provided sufficient evidence that Abiogenesis is at least possible, while my opponent has not shown how it is absolutely impossible.

I'm confused by this debate. It seems by the title like in order to win Pro would have had to argue for proof that abiogenesis is impossible and Con would have had to counter those arguments. However it seems like the debate played out where Con had to demonstrably prove that it did happen and Pro simply criticized the current hypotheses for abiogenesis! "Abiogenesis may not have happened" and "abiogenesis is impossible" are two very different debates.

However, as virtually nothing that is logically possible is mathematically impossible, perhaps I should just take the title to be an obvious case of poor wording.


# Abiogenesis and the Question of Naturalism

Previously, we left behind the comfortable confines of evolution as a theory (in the scientific sense) and headed out into one of its “frontier” areas – abiogenesis, the hypothesized transition from chemical “non-life” to life. For an American audience, “frontier” immediately calls to mind images of the Wild West – where law and order did not (yet) hold sway, outlaws and renegades were behind every barrel, and justice was dealt from the sheriff’s six-shooter (well, at least that’s how I remember the Hollywood version I saw on television as a child). In short, the frontier was a rough-and-tumble land of conflict and courage a world away from the law and order of the city – and their respective inhabitants had personalities to match.

For abiogenesis, the frontier analogy is surprisingly appropriate. When I read the scientific literature on the topic, I am instantly struck with how, well, speculative it is. This is not the scientific equivalent of quaint New England streets – this is a rough map with large swaths of uncharted territory with perhaps a few wagon tracks through it, at best. Multiple, competing hypotheses abound – was the first life a self-replicating RNA enzyme? Did life start as a metabolic pathway that only later added a heritable molecule of some sort? Did life start near deep sea vents? Did life (or some precursors to life) start somewhere else (as in not even on this planet)? All of these ideas have at least some traction in the scientific literature, and not one of them holds a majority position. It’s the scientific equivalent of the Wild West, complete with interesting personalities “dueling” each other in the scientific literature. The truth of the matter is that we just don’t know.

Let me say that again: when it comes to abiogenesis, we have almost no clue how it might have occurred.

Of course it is at this juncture, as we discussed in the last post, that a great many Christians seize on this professed ignorance to proclaim the failure of evolution as a whole. I too once did so as well, when I held antievolutionary views, so I know full well this temptation. I now realize that this makes about as much sense as claiming the map of New England to be a hopeless mess because Oregon has not yet been fully charted. Unknowns are expected at the frontier – that’s why you go there.

But… God?

But Dennis, you might say, aren’t you assuming that life had a “natural” origin? Aren’t you discounting the possibility that God might have brought life about through supernatural means? Haven’t you capitulated to “naturalism” from the outset?

There is of course much to discuss here, and the topic goes well beyond the scope of this article (or even this series as a whole). Still, the question is a valid one that merits at least a brief reply. Since abiogenesis is a frontier area of science, in principle it could have either what Christians would call a “supernatural” or a “natural” explanation – we simply do not know. Of course, any explanation in science might actually have a “supernatural” explanation, but merely appear to us as the regular outworking of “natural” law. Most Christians avoid such arguments, of course, if the science is well settled – not many of us hold out for a supernatural explanation of weather patterns or human reproduction, for example – choosing rather to see these “natural” events as part of the providence of God. No, it is typically only where less is known scientifically that Christians tend to favor supernatural explanations.

Personally, I am reluctant to ascribe to miracle what is not yet well studied scientifically, since more work may reveal a “natural” explanation – “natural”, of course, meaning part of the reproducible structure of the cosmos that God has put in place and continues to uphold that allows us to investigate it using science. In this sense, “natural laws” can be seen as part of God’s covenant faithfulness to His creation, something that my colleague Arnold Sikkema has written on (PDF) and I have found helpful. So, whether the origin of life was “natural” or “supernatural” it was of God, and there is nothing to be lost by attempting to investigate it through the scientific method. Perhaps another way to put it is that, as a scientist, I am curious just how far this regular, reproducible structure of the cosmos extends – does it extend all the way to a transition between non-life and life? Did God, in His wisdom, fashion the cosmos in such a way that chemicals could become alive? Just how deep does the rabbit hole go? While I suspect that life had a “natural” origin in the sense above, I recognize that not all Christians feel the same way. The reason for this hunch – and it is a hunch – is that I see pointers in what we doknow that suggest it to be the case.

Hints & whispers

One such “pointer” to a possible chemical past for life on earth is a feature of all living things at the very heart of what it means to be alive in a molecular sense. One of the first things one learns as a biologist is that macromolecules have divided the labor between heredity and enzymatic function: DNA is for genes, and proteins are for catalyzing reactions. Then, one learns about the various forms of RNA – a class of molecules that, interestingly, in some cases have both hereditary and enzymatic function simultaneously. Then one learns that the key enzyme at the center of the cellular machinery is in fact not a protein enzyme, as one would expect, but rather an RNA molecule – the ribosome. Ribosomes are responsible for using RNA templates to direct protein synthesis, and proteins go on to complete the loop by copying the cell’s DNA, which encodes the information for making RNA. In a significant sense, it’s all about RNA: RNA enzymes using RNA templates to make proteins that copy the cell’s DNA (which contains the crucial RNA information in a more stable form). When the chemical structure of the ribosome was determined in the early 2000s it was demonstrated that the few proteins associated with it are not part of its enzymatic function – which was a significant surprise for many molecular biologists at the time. To many of them, this absolutely crucial RNA enzyme using RNA templates at the center of cellular life was suggestive – suggestive that life once passed through a stage where RNA was the major player in heredity and enzymatic function, rather than the DNA/protein world of the present.

Next, we’ll explore this proposed “RNA world” – a hypothesis that has gained some experimental support in recent years.


Ignoring Biology and Chemistry

Alas, already the esteemed astronomer has ignored the physics. He assumes that monomers add by a Poisson process, which means the rate of polymerization is independent of length. It makes for pretty math and drops a few thousand orders of magnitude from the probability, but it totally ignores both the biology and the chemistry. For the record, that’s the second tooth fairy.

Just to make things worse, he assumes clay will catalyze the reaction, seemingly unaware that clay is a bio-mineral that doesn’t form on its own. But out of mercy, we’ll let that tooth fairy pass.

Then he adds an “evolution” probability to his calculation. I assume that this is the probability that the twin monomers will not only produce offspring, but twin mutated offspring. Now evolution is one of the requirements for living things, and he wants living things to be created by evolution! There are numerous quotes by the great minds of Darwinism saying that abiotic chemistry does not possess evolution. It really feels like this step is buying the farm. So this seems to be a third tooth fairy.


Abiogenesis

Abiogenesis is one of the modern evolutionary theories about how life originated. It referred to the now-extended hypothesis of the spontaneous generation. It was once believed that complex animals such as rats, maggots, etc. Although the details of this process are still unknown, the conventional scientific hypothesis is that the transformation from inanimate to living beings was not a single event, but an evolutionary process of increasing complexity involving molecular self-replication, self-assembling, autocatalysis, and cell proliferation. Although the phenomenon of indigenization is not controversial among scientists, its possible mechanisms are rarely understood. No evidence has been found as to where or when such a life could be created. Indeed, what we know in science today indicates that abiogenesis could not have occurred under any of the natural possible conditions.

Researchers study abiogenesis through a combination of molecular biology, paleontology, astronomy, oceanography, biophysics, geochemistry and biochemistry, and aim to determine how pre-life chemical reactions evolved life. The study of abiogenesis can be geophysical, chemical, or biological, with the latest method attempting three syntheses as well as life emerging in a different state than the world today. Miller theorist said that over billions of years these molecules could combine into self-replicating versions such as RNA and DNA. Subsequent laboratory tests have confirmed these results in the following decades. Any successful theory of eigengenes must explain the origin and interaction of these classes of molecules. Several specific experiments have provided ample evidence that the molecular structure of many cells can be formed from inorganic solutions with an input of energy. Both polypeptides (proteins) and RNA are synthesized in this way. The classic 1952 Miller-Uri test and similar studies proved that most amino acids, the chemical constituents of proteins used in all organisms, can be synthesized from inorganic compounds for the purpose of replicating the initial state. The various elements were meant to mimic the primitive ocean, the pre-biological environment, and heat (in the form of lightning), respectively. A week later, Miller and Yuri discovered that ordinary organic molecules, including amino acids (the building blocks of proteins), were formed in the mimicry of the early Earth.

Abiogenesis, the concept originated from lifeless on Earth 3.5 million years ago. The final speculation is that biology could begin 17 million years after the Big Bang, in a habitable era, and that life could last all over the world. Abiogenesis gives birth to most Primitive form of life Possible. These can be as simple as replicating protein molecules. Life is known as the only place on earth for the universe, and evidence of the Earth’s fossils informs most studies of Abyssinia. Earth’s age is estimated at 4.54 billion years He started the undisputed evidence of life on Earth at least 3.5 billion years ago, and probably the earliest epoch-making epoch began to follow the molten Hadian Inn. Thus, the theory of spontaneous generation became obsolete and was transmitted by the theory of biogenesis. The basic theory of biological genesis lies in the idea that life originates from a similar life form. However, extrinsic technologically intelligent life, in contrast to the simple microbial life described by Hedges, can be so rare that the closest neighbors of the human race may be left out of the possibility of our contact with them. Astronomer Jill Tarter of the STI Institute said that the causes of the Drake equation are a means of organizing our lack of knowledge.


Moving to a DNA world

Demonstration that biological molecules and membranes can arise in an abiotic environment is not a demonstration of the emergence of life. It shows only what might have happened in the transition from non-living chemistry to the eventual formation of life. It does, however, show that a necessary step in abiogenesis – the spontaneous emergence of complex organic molecules – is not only possible, but likely under the right conditions.

Theoretically, continuous rearrangement and construction of larger and larger organic molecules from chemical building blocks that would form on the early Earth should eventually lead to molecules that can copy themselves. That’s because the bigger an organic molecule gets, the more functional chemical groups it has. Functional groups are sections of molecules with atoms other than carbon, such as oxygen, nitrogen, and phosphorus, which like to hold onto electrons. This allows for electrons to be moved around between parts of the molecule and between the molecule and other molecules. Also, the bigger a molecule gets, the more it’s able to bend and twist around. This capability, together with the capability to move around a lot of electrons, &^means it’s possible, simply by luck, for any random, very large organic molecule with a lot of nitrogen, oxygen, and phosphorus atoms to have some enzymatic capability –that is, to be able to catalyze chemical reactions.

Certain sets of reactions catalyzed by a molecule can result in the molecule making a copy of itself. Thus, with plenty of building materials in a Haldane soup, as time goes on, it is likely that self-replicating molecules would emerge. The first self-replicating molecule would have only crude copying ability. But, since it would not copy itself exactly, each new “copy” would be a little different than the “parent” molecule. Randomly, a newly copied molecule might have the ability to copy slightly better than the molecule that made it. Natural selection would then work for non-living chemical molecules similar to how Darwin described it working for living organisms. Those molecules copying better would make more copies using building blocks taken from the breakdown of other molecules that could not copy themselves so well.

Self-copying molecules enclosed in membranes would fare even better because they would be held close together with other chemicals. But for life to really begin, there has to have been a molecule whose copying ability was extremely good. Today, there is such a molecule: DNA. However, DNA is incredibly complex and this makes for a chicken and egg kind of dilemma.

In the 1980s, scientists began to realize that not all enzymes are proteins. Scientists dissected some cell components called ribosomes and found that they are made of protein and RNA. What was strange was that some of the RNA molecules actually work as enzymes. They can catalyze chemical changes in themselves and in other RNA molecules.

Like DNA, RNA can hold genetic information, but RNA is less complex than DNA (Figure 8). Consequently, a hypothesis called the “RNA world” was proposed independently by three different researchers: Leslie Orgel, Francis Crick, and Carl Woese. It’s a keystone in origins of life research today. The idea is that RNA emerged on Earth prior to DNA and was the genetic material in the first cells (or in the first cells on a different world, if life began somewhere else).

Figure 8: A comparison of Ribonucleic acid (RNA) and Deoxyribonucleic acid (DNA).

Today, no known bacterial cell or other fully-fledged life form uses RNA the way that we use DNA, as the storage molecule for genetic information. But there are RNA viruses. Not all viruses are RNA viruses some use DNA to hold genetic instructions, just as our cells do. But if RNA is adequate as the only genetic material in some viruses, it’s easy to imagine RNA also being the only genetic material in an early bacterium, or other singled-celled creature that could have existed on the early Earth.

It’s not hard to image how the transition from RNA to DNA might have occurred. As with the evolution of everything else, there would have been mistakes. In living organisms today, DNA stores genetic information over the long term and DNA sequences are transcribed into RNA sequences, which then are used to put together sequences of amino acids into proteins (see our Gene Expression: An overview module). Essentially, DNA is an additional layer beyond RNA and the proteins that RNA makes. RNA sequences could have been the genes before a mistake created DNA. Being more stable chemically than RNA, DNA took over the job of storing genetic information. This gave RNA a chance to get better at translating genetic information into proteins.

That would have been an enormous step in life’s evolution. It also would mean that life was not here all at once. Rather, abiogenesis occurred in increments or steps during prebiotic, chemical evolution. Thus, entities must have existed along a spectrum from nonliving to living, just as viruses today have characteristics of both living and nonliving entities. We don’t know the precise abiogenesis pathway, but scientists have worked out each of the major steps necessary to go from nonliving chemistry to self-sustaining cells. Importantly, scientists also have conducted laboratory experiments demonstrating that each step is possible. Unlike the days of Anaximander, Darwin, or even Haldane, there are no big holes or theoretical barriers to abiogenesis. Scientists have a good idea of how it probably happened. Still, in terms of the details within each major step, that is where science is now focused on getting some answers.

Summary

Since prehistoric times, people have pondered how life came to exist. This module describes investigations into the origins of life through history, including Louis Pasteur’s experiments that disproved the long-held idea of spontaneous generation and and later research showing that the emergence of biological molecules from a nonliving environment – or abiogenesis – is not only possible, but likely under the right conditions.

Key Concepts

Theories about the origins of life are as ancient as human culture. Greek thinkers like Anaximander thought life originated with spontaneous generation, the idea that small organisms are spontaneously generated from nonliving matter.

The theory of spontaneous generation was challenged in the 18th and 19th centuries by scientists conducting experiments on the growth of microorganisms. Louis Pasteur, by conducting experiments that showed exposure to fresh air was the cause of microorganism growth, effectively disproved the spontaneous generation theory.

Abiogenesis, the theory that life evolved from nonliving chemical systems, replaced spontaneous generation as the leading theory for the origin of life.

Haldane and Oparin theorized that a "soup" of organic molecules on ancient Earth was the source of life's building blocks. Experiments by Miller and Urey showed that likely conditions on early Earth could create the needed organic molecules for life to appear.

RNA, and through evolutionary processes, DNA and the diversity of life as we know it, likely formed due to chemical reactions among the organic compounds in the "soup" of early Earth.



Comments:

  1. Tayte

    Bravo, I think this is a great idea.

  2. Goltirg

    Between us, I recommend looking for the answer to your question on google.com

  3. Grorn

    I think it does not exist.



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