Origin of Life - Theories Of The Origin Of Life
acids amino molecules atmosphere
All cultures have developed stories to explain the origin of life. During medieval ages, for example, European scholars argued that small creatures such as insects, amphibians, and mice appeared by "spontaneous generation"—natural self-assembly of nonliving ingredients—in old clothes or piles of garbage. Italian physician Francesco Redi (1626?–1698) challenged this belief in 1668, when he showed that maggots come from eggs laid by flies, rather than forming spontaneously from the decaying matter in which they are found.
A series of experiments conducted in the 1860s by the French microbiologist Louis Pasteur (1822–1895) also helped to disprove the idea that life originated by spontaneous generation. Pasteur sterilized two containers, both of which contained a broth rich in nutrients. He exposed both containers to the air, but one had a trap in the form of a loop in a connecting tube, which prevented dust and other particles from reaching the broth. Bacteria and mold quickly grew in the open container and made its broth cloudy and rank, but the container with the trap remained sterile. Pasteur interpreted this experiment as indicating that microorganisms did not arise spontaneously in the open container, but were introduced by dust and other airborne contaminants.
Although Redi, Pasteur, and other scientists thoroughly disproved the theory of spontaneous generation as an explanation for the origin of present-day life on whatever scale, they raised a new question: If organisms can arise only from other organisms, how then did the first organism arise?
Charles Darwin (1809–1882), the famous English naturalist, suggested that life might have first occurred in "some warm little pond" rich in minerals and chemicals, and exposed to electricity and light. Darwin argued that once the first living beings appeared, all other creatures that have ever lived could have evolved from them. In other words, spontaneous generation did occur—but only a long time ago, when the first, minimally complex forms of life would have faced no competition from more-competent cells. Many of the laboratory experiments that would eventually be conducted to shed light on the origin of life have been variations on Darwin's "warm little pond." First, however, another influential suggestion regarding the origin of life was provided by Russian scientist Aleksandr Oparin (1894–1980) and English scientist J. B. S. Haldane (1892–1964). Oparin and Haldane suggested in the 1920s that the atmosphere of billions of years ago would have been very different from today's. The modern atmosphere is about 79% nitrogen (N2) and 20.9% free oxygen (O2), with only trace quantities of other gases. Because of the presence of oxygen, which combines readily with many other substances, such an atmosphere is termed oxidizing. Oparin noted that oxygen interferes with the formation of organic compounds necessary for life by combining with their hydrogen atoms and reasoned that the atmosphere present when life began must have been a reducing atmosphere, which contained little or no oxygen but had high concentrations of gases that can react to provide hydrogen atoms to synthesize the compounds needed to create life. Oparin and Haldane suggested that this primordial, reducing atmosphere consisted of hydrogen (H2), ammonia (NH3), methane (CH4), and additional simple hydrocarbons (molecules consisting only of carbon and hydrogen atoms). Oxygen could not have been present in large quantities because it is chemically unstable, and is only maintained as a major ingredient of the atmosphere by the action of green plants and algae—that is, by life itself. Before life, the Earth's atmosphere could not have been strongly oxidizing.
According to this theory, energy for rearranging atoms and molecules into organic forms that promoted the genesis of life came from sunlight, lightning, or geothermal heat. This model of the early environment became especially popular among scientists after a U.S. graduate student of physics named Stanley Miller (1930–), then studying at the University of Chicago, designed an experiment to test it. In 1953 Miller filled a closed glass container with a mixture of the gases that Oparin and Haldane suggested were in the ancient atmosphere. In the bottom of the container was a reservoir of boiling water, and above it an apparatus that caused electrical sparks to pass through the gas mixture. After one week of reaction, Miller found that amino acids and other organic chemicals had formed from the gases and water. In the years since Miller reported his results, other researchers have performed more sophisticated "warm little pond" experiments, and have been to synthesize additional amino acids and even nucleic acids, the molecules that organize into RNA and DNA, which in turn encode the genetic information of organisms.
Subsequent research influenced by these experiments led many scientists to believe that the concentration of organic molecules in the primordial, nutrient-laden, warm "ponds" (which may have been tidal pools, puddles, shallow lakes, or deep-sea hot springs) increased progressively over time. Eventually more complex molecules formed, such as carbohydrates, lipids, proteins, and nucleic acids. The complexity gap between simple nucleic acids and self-replicating RNA or DNA is, however, large; therefore, some scientists have theorized that assembly of more complex compounds from simpler ones may have occurred on the surface of oily drops floating on the water surface, or on the surfaces of minerals—inanimate objects whose atomic structure might have provided a template for stringing together nucleic acids and giving them a place to "live" until free-floating cells protected by lipid membranes could evolve.
However, some scientists believe that the young Earth was too inhospitable a place for life to have developed on its surface at all; lacking O2, the atmosphere would also have lacked its present-day stratospheric layer of ozone (O3), which screens large quantities of harmful ultraviolet radiation from the surface. They believe that a more likely environment for abiogenesis (life from prelife) was in the vicinity of deep-sea vents, holes in the crust under the ocean from which hot, mineral-laden water flows.
Furthermore, many scientists today believe that the prelife atmosphere may not have been as strongly reducing as the one proposed by Oparin and Haldane and used in Miller's experiment. They assert that volcanoes added carbon monoxide (CO), carbon dioxide (CO2), and nitrogen to the early atmosphere, which may even have contained traces of oxygen. Nevertheless, more recent experiments of the Miller type, run using a less reducing atmosphere, have also resulted in the synthesis of organic compounds. In fact, all 20 of the amino acids found in organisms have been created in the laboratory under experimental conditions designed to mimic what scientists believe the prelife Earth was like billions of years ago—whether using Miller's model or its less-reducing competitors.
But in the absence of life, how did these amino acids link together into more complex compounds? Living cellular chemistry links amino acids together using specific enzymes to form particular proteins. An amino acid is any compound which contains at least one amino group (NH2) and one carboxyl group (-COOH). When amino acids are linked, a hydrogen molecule and a hydroxyl group (OH) are removed from each amino acids, which then link up into a protein chain, while the hydrogen and hydroxyl link up as a water molecule (H + OH = H2O). Without enzymes, amino acids do not link up in this way—or, as a biochemist might describe it, polymerization does not proceed. How, then, could amino acids have joined to form proteins without the proteins termed enzymes to help them? One possibility is that amino acids may have joined together on hot sand, clay, or other minerals. Laboratory experiments have shown that amino acids and other organic building blocks of larger molecules, called polymers, will join together if dilute solutions of them are dripped onto warm sand, clay, or other minerals. The larger molecules formed in this way have been named proteinoids. It is easy to imagine some version of Darwin's "warm little pond"—a soup of spontaneously-formed amino acids—splashing onto hot volcanic rocks. Clay and iron pyrite have particularly favorable properties making them good "platforms" for the formation of larger molecules from smaller building blocks. One recently proposed theory of the origin of life suggests that tiny ( .01-mm diameter) hollows in iron sulfide minerals, such as are deposited in the vicinity of deep-sea hot springs, might have incubated the earliest life chemistry. Iron sulfide catalyzes the formation of organic molecules, and is used by some modern bacteria for this purpose. Sheltered in tiny iron-sulfide caverns, prebiotic chemistry might have developed at leisure, leaving this protected environment only after evolving a protective lipid membrane. This theory, however, like all theories of the origin of life, has its scientific opponents, and awaits the production of confirming or disconfirming laboratory evidence.
Proteinoids produced in laboratories can cluster together into droplets that separate, and that may protect their components from degrading influences of the surrounding environment. These droplets are like extremely simple cells, although they can not reproduce. Such droplets are called microspheres. When fats (i.e., lipids) are present, the microspheres that form are even more cell-like. If a mixture of linked amino acids called polypeptides, sugars called polysaccharides, and nucleic acids is shaken, droplets called coacervates will form. All of these kinds of droplets are called protobionts, and they may represent a stage in the genesis of cellular life.
The formation of amino acids and other organic compounds is presumed to have been a necessary step in the genesis of life; it is certain, at least, that somewhere along the line all life became dependent on DNA and RNA for reproduction. Scientists thus presume that the first self-replicating molecules were similar to the nucleic acids of modern organisms. (These early molecular systems need not have been as complex as the self-replicating systems that comprise modern cells. Researchers have recently shown, by deleting genes, that even the genetically simplest bacteria alive today can reproduce with much less than their full natural complement of DNA.) Once molecules that could self-replicate were formed, the process of evolution would account for the subsequent development of life. The particular molecules best adapted to the local environmental conditions would have duplicated themselves more efficiently than competing molecules. Eventually, primitive cells appeared; perhaps coacervates or other protobionts played a role at this stage in the genesis of life. Once cells became established, evolution by natural selection could have resulted in the development of all of the life-forms that have ever existed on Earth.
User Comments
10 months ago
Read the bible
'1In the beginning God created the heaven and the earth.2And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.3And God said, Let there be light: and there was light.4And God saw the light, that it was good: and God divided the light from the darkness.5And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.6And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.7And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.8And God called the firmament Heaven. And the evening and the morning were the second day.9And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so.10And God called the dry land Earth; and the gathering together of the waters called he Seas: and God saw that it was good.11And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so.12And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good.13And the evening and the morning were the third day.14And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years:15And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.16And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.17And God set them in the firmament of the heaven to give light upon the earth,18And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.19And the evening and the morning were the fourth day.20And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven.21And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good.22And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth.23And the evening and the morning were the fifth day.24And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.25And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good.26And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.27So God created man in his own image, in the image of God created he him; male and female created he them.28And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.' Genesis 1:1-28 FYI Darwin recalled his theory and admitted he was wrong....
10 months ago
Read the bible
'1In the beginning God created the heaven and the earth.2And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.3And God said, Let there be light: and there was light.4And God saw the light, that it was good: and God divided the light from the darkness.5And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.6And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.7And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.8And God called the firmament Heaven. And the evening and the morning were the second day.9And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so.10And God called the dry land Earth; and the gathering together of the waters called he Seas: and God saw that it was good.11And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so.12And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good.13And the evening and the morning were the third day.14And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years:15And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.16And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.17And God set them in the firmament of the heaven to give light upon the earth,18And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.19And the evening and the morning were the fourth day.20And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven.21And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good.22And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth.23And the evening and the morning were the fifth day.24And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.25And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good.26And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.27So God created man in his own image, in the image of God created he him; male and female created he them.28And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.' Genesis 1:1-28 FYI Darwin recalled his theory and admitted he was wrong....
10 months ago
@Questions
If scientist think they know how life forms were made, why don't they create life? They know how it happened right? Also if I read the Bible, and all that it says is true, yet I do not believe, doesn't that mean I go to Hell? But if I do believe I get to go to Heaven. Even if it is fake what do I have to lose? It says God made "animals", maybe those animals were dinosaurs, hm? Scientists don't know how old the Earth is because they can't. Oh and when it says seven days in the Bible we don't know what it means by days. t could mean seven years. Don't take everything so literal. God talked to people who wrote down what he told them to and recorded previous and current events. In other words it did come from God. Do your research before you go ranting about something you know nothing about. By the way David, God is life. So it's not "life from non-life". And if it is that we evolved then why are there still apes? And they expect me to believe the Universe popped out of nowhere? Highly doubted. An outside force, such as God, creating it is much more likely. Those people were killed because other people are being human. The people that killed them are probably people like you. Instead of telling us to re-read the article, why don't you go re-read the Bible?
about 1 year ago
Truth finder
The Law of Mathematics Disproves Evolution
Suppose you have 18 people and you want to figure out how many different ways they can line up in a row, for example, three letters can be lined up 6 different ways, ABC, CBA, BAC, CAB, BCA, ACB. What you do to figure how many different ways there are to line them up is you take 1x2x3 and you get six, so for 18 you take 1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16x17x18= Something Really Big? Yes, But the Correct answer is, 6,402,373,705,728,000 or six quadrillion, four hundred and two trillion, three hundred seventy-three billion, seven hundred and five million, seven hundred twenty-eight thousand.
So what’s the point?! Your body is made up of cells, those cells are made up of proteins and those proteins are made up of amino acids. It takes 400 amino acids to make a protein and they have to be lined up in PERFECT order. If they change positions every minute it would take at least, if ever, 12,000,000,000 years to get 18 of those 400 amino acids lined up in the right order. 12 billion years is how old evolutionists think the earth is, so you can see that they simply don’t have enough time. To make matters worse it takes 60,000 proteins to make a cell and there are trillions of cells in your body. God is the Creator
11 months ago
Anonomous
This is wayyy to long, you should edit it so that it's more interesting to your readers. Also I kind of fell asleep less than half way through... sorry to say.
10 months ago
Anonymous
I didn't even make it halfway...someone bring me a pillow...
10 months ago
CoreyM
this is directed at the person named "questions"
we all have our own beliefs and have a complete right to them. here is just something to consider, if you want to bash the bible please do so in an accurate manner. if you want to defend evolution do so in an accurate manner. the person named truth finder at least gave a well detailed argument and all you did was put exlamation points and bold letters. and if look back at the argument it takes more faith to believe that all life came from single amoeba cell than a creator. next when you say people died over the bible, what do you mean? people die over food and territory everyday, no offense but ive seen better arguments from nine year old children. any reply would be great from you and i will check in to see if you've read my comment
over 1 year ago
Excellent answer to a google search for origin of life. I am developing a resource to inspire an awareness of the adventure and magic that is inherent in the search for truth via a scientific discipline. The issues around abiogenesis are deeply challenging, inherently threatening and wonderfully exciting if engaged with. thanks!
7 months ago
researchers
it is boring, it really need to be edited.
about 1 year ago
if "spontaneous generation"is real,then, the world will be more scary than i thought, somethin like, one day, you accedintally spit on the water reservoir with an unknown developed chemical and suddenly, a vicious monster developed,brrrrr, biololgy sounds deppressing!
over 1 year ago
Pitman
The problem with all 'origin of life ' theories is that they don't work in reality. When the conditions that are specified by the theory are reproduced in the lab, they don’t yield the expected result which is life or primitive cells at least. We thus have to rely on our imagination and computer animation to 'see' the theory producing anything worth consideration, miller made amino acids and later fox made 'protienoids'. The problem remains, no life. If anyone thinks that the efforts of scientists have come anywhere near producing life, then that means that they need a serious biology lecture so that they can understand what life is.
about 2 years ago
There seems to be a flaw in your argument. Your article begins by saying that "spontaneous generation" (life from non-life) doesn't happen, and then ends by explaining the origins of life by exactly that. There has been no example of life being formed from non-living materials. Life only comes from life. And you don't explain where the vast amount of information coded within the DNA comes from.
My 2 cents,
David
10 months ago
Ontheotherhand
@ Questions
Your assuming that since amino acids have be recreated in lab conditions, that means new life.....with an honest open mind read this linked scientific article.
http://www.icr.org/article/evolution-hopes-you-dont-know-chemistry-problem-wi/
6 months ago
I liked it, the article was interesting. Also, religious people shouldn't be reading these articles just so they can say "the Bible is the way" cause its not true. I believe that Earth was created by the universe, not a god.
about 1 year ago
A more recent thoery, tested with the use of complex computer models, gives credit to the ealier Stanley Miller experiment. I'll try to sum it up as best as I can but here are the essentials.
Heat, lightning, the volatile conditions of an early Earth have been proven to contain everything necessary for the formation of simple organic compounds. Nuceic acids etc. The problem with this theory was that there was nothing to show how these acids bonded together to form complex strands of RNA for example. The recent computer model I refer to proves that more complex compounds can be formed when large satelites collide with the Earth. The transfer of heat and energy from a large meteor is enough to form more complex compunds.
about 2 years ago
John Catan
David, in reply to your observation; the author is pointing out that "spontaneous generation" doesn't happen as it was originally proposed centuries ago. i.e. dirty rags do not turn in to maggots and rats. While scientists still do not know exactly how life first began they are making significant progress in learning how it might have begun. Scientific American had an article recently that talks about the latest developments in this area of study. I would caution that if we just accept that life comes from life and do not endeavor to learn how it really happened,we will never know.
SciaAm article link: http://www.scientificamerican.com/article.cfm?id=origin-of-life-on-earth
3 months ago
student with brains
Darwin did recall his theory and admitted he was wrong....so if the man who brought this subject alive say that it is wrong, why are u still going with this?
4 months ago
If you are in a not good position and have no cash to move out from that, you would require to receive the credit loans. Just because it will help you for sure. I take sba loan every year and feel myself OK because of that.
9 months ago
Dov Henis
EarthLife Genesis By 2011 Data
- Earth's primal ORGANISMS are RNAs, good Sun radiation absorption-constraint, self-replicating mass formats. Corroborating
evidence: life's chirality and life's sleep.
- All EarthLife is evolved RNAs. All self-replicators are organisms, including genomes. DNA selected for some genomes being
energetically stabler than RNA.
- Life's drive: RNA's natural selection, enhance-maintain Earth's biosphere, exploit-postpone Sun's and Earth's energy prior
to their fueling universe expansion.
- Drive of Life's evolution: Natural selection is ubiquitous for ALL mass-formats/spin-arrays; must ingest energy-or-mass to
delay-postpone eventual own reconversion to energy, all of which is destined to fuel expansion of the universe. Universe
expansion reconverts singularity's mass to energy. Eventually, as nearly all massfuel is consumed, expansion will be
overcome by gravity to initiate re-empansion to singularity, reconverting ALL energy to ALL mass.
Dov Henis
(Comments From 22nd Century)
http://www.scientistsolutions.com/t18894-update+comprehension+of+universe_life+evolution%2c+of+rna_dna+mismatch_relati.html
http://www.the-scientist.com/community/user/profile/1655.page
Seed of Human-Chimp Genomes Diversity
http://pulse.yahoo.com/_2SF3CJJM5OU6T27OC4MFQSDYEU/blog/articles/53079
03.2010 Updated Life Manifest
http://www.the-scientist.com/community/posts/list/54.page#5065
Evolution, Natural Selection, Derive From Cosmic Expansion
http://darwiniana.com/2010/09/05/the-question-reductionists-fear/
Rethink Evolution/Natural Selection
http://darwiniana.com/2011/03/29/comment-from-dov-henis/comment-page-1/
10 months ago
Questions
Oh and also the earth may be 6 billion to 24 billion years of age. Less or more NO one can really tell. Plus since the earth is about that old we don't know what might of happened for all we know some other life forms crashed again on a meteor or comet.
over 1 year ago
You
Why does anyone have to agree with theories and such? Why can't we make our own assumptions and get on with life instead of wondering where it came from?
almost 2 years ago
Gareth
For Darwin, evolution was just a theory, one that he knew could still take a lot of study to prove, but the problem is that people today have turned it into a religion, and a reason to hate theism.
10 months ago
Questions
Ok. Truth finder where in the bible does it say dinosaurs came from? Simply it doesn't. It says that there was no earth or sun to begin with. It says that god made the sun and earth. So tell me this. If god created the sun and the earth and then a human. Where did dinosaurs come from? Also I have another question. Where did the bible come from? Did it come from god? Hell no! If history tells correctly Jesus the prophet of Christianity was a JEW! Also if god really is real and if he really made the bible and the teachings in it. Then why were so many people killed over it? If you could answer some of these for me that would be great. And also some of you will need to go back and re-read the article. OH Truth Finder what you said, doesn't make any sense at all. You know why because SCIENTISTS have successfully recreated earths conditions from when it was young and created!!!!! Life with only a little water and some gas. Plus if you READ the whole article it says it is completely possible that some sort of meteor of comet may have collided with earth essentially giving it water, and proteins. What is a comet made out of? Ice and other materials. Well I got to go I'll come back with more detailed information about what I'm talking about.
27 days ago
This is stupid
This is super boring. But I relize the geeks and nerds who read this stuff for fun don't have friends or girlfriends and can't find any thing else to do. Don't worry guys, I promise to never read this stuff unless force to for school, just for you :) Really you should be thanking me :)