stanley miller experiment ap bio

• Homeschoolers
• College Biology
• High School Biology
• Human Biology
• AP Bio Review
• Setup Guide/User’s Manual
• Teaching Guides
• Music Videos
• Biomania App

Early Earth, Key Steps in the Emergence of Life, Stanley Miller and the Primordial Soup

Looking for a student learning guide? It’s linked in the main menu for your course. Use the “Courses” menu above.

1. Early Earth was Different from Present-Day Earth

Earth today has environments that would be difficult for you and me to survive in. Imagine, for example being dropped into the middle of the broiling Sahara desert or the frozen interiors of Greenland or Antarctica. But today’s Earth is a garden planet compared to how our planet was in its infancy.

In the previous tutorial, we learned that microfossils and fossilized stromatolites show clear evidence of life on Earth by 3.5 bya, with less convincing evidence for life even earlier than that. What was our planet like when life first emerged? Take a look at the depiction of early Earth below, and write down a few observations in your student learning guide. 

The period that spans the time from the Earth’s formation 4.6 bya until about 4 bya was so hostile that it’s been named the Hadean eon. The word “Hadean” is derived from Hades , the land of the dead in ancient Greek mythology, and is roughly synonymous with the word “hell.” Following the Hadean period is the Archaean eon, which spans the period from 4.0 to 2.5 bya. Sometime during the Hadean eon, or within one or two hundred million years of the start of the Archean eon, life emerged on planet Earth. Here’s what this hellish world was like.

1a. The atmosphere lacked free oxygen (O 2 )

The red sky depicted above indicates the different compositions of the Hadean and Archaean atmospheres. In terms of the origin of life, the most important difference was the lack of atmospheric oxygen (O 2 ). Today, our atmosphere is about 21% oxygen. That oxygen is there because plants and photosynthetic bacteria have, for the past several billion years, been splitting water molecules apart and releasing molecular oxygen. Before life emerged, there would have been no photosynthesis and no free oxygen.

There are multiple lines of evidence for early Earth’s oxygen-free atmosphere. Minerals from the early Earth include iron-based compounds that could not have formed in the presence of oxygen. That’s because oxygen is an oxidizing agent that steals electrons from other compounds. When elemental iron is exposed to oxygen, the iron is oxidized to rust. Huge deposits of rust (such as the banded iron formation shown at right) start to form on Earth at about 2.4 bya, a period that is associated with the first accumulation of photosynthetically originated oxygen in the seas.

The atmospheres of the other rocky planets (Venus and Mars) are also models for what Earth’s atmosphere would be like in the absence of life. Take a moment and study the table below:

The key point is the complete lack (on Venus) or trace amount (on Mars) of molecular oxygen in the atmospheres of the other planets of the solar system.

So what gases were in early Earth’s atmosphere? Probably mostly nitrogen gas (N 2 ) and carbon dioxide (CO 2 ). These gases were either emitted from volcanoes or arrived in the comets and meteors that were bombarding the Earth at that time.

1b. Meteor and Comet Strikes were Common

The entire Hadean and the early Archaean eon is referred to as the period of heavy bombardment . Earth, during this time, was being pummeled by meteors and comets. These impacts would have released enormous amounts of energy, melting the crust in the surrounding area.

1c. The Moon was Much Closer

The moon is thought to have formed as a result of a massive impact between Earth and another planet that was about a third of the Earth’s size (approximately the size of Mars). The moon formed from the debris that was flung into space. When the moon first coalesced, it was 10 to 20 times closer (source: space.com ) than it is now. Tidal forces exerted by the Moon would have been much stronger than now (because gravitational force varies as the square of the distance between two objects, so reducing the distance by ten times would have increased the gravitational force by 100 times).

1d. There was more volcanic activity

Volcanic activity is caused by heat within the Earth. Most of that heat comes from radioactive decay. A younger Earth would have had more radioactive isotopes, more heat, and more volcanic activity.

1e. There was very little land

The continents have grown over time through a process called accretion . Today, the Earth’s surface is about 30% land and 70% ocean. On early Earth, the amount of land would have been less. Once the Earth had cooled enough to allow for liquid water to accumulate on the surface, that surface would have been covered by a global ocean, with a few volcanic islands peeking through (source: New Scientist ).

2. Early Earth: Checking Understanding

Some of the conditions described above would have made the emergence of life impossible on the surface of our young planet impossible. These include meteor impacts that would have melted the crust and destroyed any early emerging life forms. Other conditions, such as the lack of oxygen in the atmosphere, were conducive to the emergence of life. That’s because oxygen, with its propensity for stealing electrons, can destroy complex molecules like nucleic acids and proteins. A lack of oxygen thus might have promoted the emergence of life on Earth. As we’ll see in what follows, other features of the young Earth give us clues about where and how life might have arisen. But first, let’s consolidate your learning.

[qwiz random = “true” qrecord_id=”sciencemusicvideosMeister1961-Early Earth, Checking Understanding”]

[h]Conditions on the Early Earth

[q] Unlike our current atmosphere, the early Earth’s atmosphere was almost certainly lacking in   [hangman]

[c]IG94eWdlbg==[Qq]

[f]IEdyZWF0IQ==[Qq]

[q] During the period of heavy [hangman], there were frequent impacts of meteors and [hangman]. x

[c]IGJvbWJhcmRtZW50[Qq]

[f]IEdvb2Qh[Qq]

[c]IGNvbWV0cw==[Qq]

[f]IEV4Y2VsbGVudCE=[Qq]

[q] If you were able to visit the Earth about 3.5 bya, the days would be shorter. In the evening, you’d see a much brighter and closer [hangman]. As a result, you’d have to be careful if you approached the shore because there would be much higher [hangman]. And, you’d have to remember to bring some kind of breathing apparatus, because of the lack of [hangman] in the air. x

[c]IE1vb24=[Qq]

[c]IHRpZGVz[Qq]

[f]IENvcnJlY3Qh[Qq]

[q] In the young Earth, there would be much more activity from [hangman]. A few of these would poke above the surface of a world-covering [hangman], creating the only land surfaces. x

[c]IHZvbGNhbm9lcw==[Qq]

[c]IG9jZWFu[Qq]

[q multiple_choice=”true”] Which of the following dates is most likely for the origin of life?

[c]IDQuNiBieWE=[Qq]

[f]IE5vLiBUaGF0JiM4MjE3O3Mgd2F5IHRvbyBlYXJseS4gVGhhdCYjODIxNztzIHdoZW4gdGhlIEVhcnRoIHdhcyBmaXJzdCBmb3JtaW5nLg==[Qq]

[c]IDQuMSBieWE=[Qq]

[f]IE5vLiBUaGF0JiM4MjE3O3MgZHVyaW5nIHRoZSBwZXJpb2Qgb2YgaGVhdnkgYm9tYmFyZG1lbnQuIEFueSBlbWVyZ2luZyBsaWZlIHByb2JhYmx5IHdvdWxkIGhhdmUgYmVlbiBkZXN0cm95ZWQgYnkgaW5jb21pbmcgbWV0ZW9ycyBhbmQgY29tZXRzLg==[Qq]

[c]IDMuOC BieWE=[Qq]

[f]RXhjZWxsZW50ISBZb3UmIzgyMTc7dmUgY2hvc2VuIGEgZGF0ZSB0aGF0JiM4MjE3O3MgYmV0d2VlbiB0aGUgZW5kIG9mIHRoZSBwZXJpb2Qgb2YgaGVhdnkgYm9tYmFyZG1lbnQsIGFuZCBiZWZvcmUgdGhlIGRhdGUgZm9yIHRoZSBlYXJsaWVzdCBmb3NzaWxpemVkIGxpZmUuIExpZmUgaGFkIHRvIGVtZXJnZSBzb21ld2hlcmUgaW4gYmV0d2Vlbi4=[Qq]

[c]IDMuNSBieWE=[Qq]

[f]IE5vLiBBcyBzaG93biBieSBmb3NzaWxpemVkIHN0cm9tYXRvbGl0ZXMgYW5kIGFzc29jaWF0ZWQgbWljcm9mb3NzaWxzIGZyb20gdGhhdCBwZXJpb2QsIGxpZmUgd2FzIGFscmVhZHkgd2VsbCBlc3RhYmxpc2hlZCBieSAzLjUgYnlhLiBDaG9vc2UgYW4gZWFybGllciBwZXJpb2Qu[Qq]

[q] One piece of evidence for the oxygen-free atmosphere of early Earth is the presence of certain [hangman] containing minerals that could not have formed if oxygen were present in the air. x

[c]IGlyb24=[Qq]

[q] The oxygen in our atmosphere is the product of  [hangman], which splits water molecules apart.  x

[c]IHBob3Rvc3ludGhlc2lz[Qq]

[q] During photosynthesis, water is combined with carbon dioxide to produce carbohydrates. Oxygen is released as a waste product. The source of the oxygen is [hangman]. x

[c]IHdhdGVy[Qq]

3. Origin of Life: Key steps

In what follows, we’ll learn about how the first populations of living cells could have emerged from non-living matter; how chemistry developed into biology.

The table below shows some of the key steps required for the emergence of the first living cells. Use the biology you know (and logic) to fill in the blanks. Note that step 1 had to come first, but there’s no consensus on the sequence of the steps after that (and they could have all happened at the same time).

The one term you might not know is “abiotic.” It means “without life,” or “non-living.” For example, in ecology, we talk about abiotic factors such as air temperature or rainfall, while predatory animals are a biotic factor.

[qwiz qrecord_id=”sciencemusicvideosMeister1961-Key Steps in the Origin of Life: Interactive Table”]

[h]Interactive Table: Key Steps in the Origin of Life

[i] An origin of life haiku

When life first emerged

Was it heredity first,

Or metabolism?

[q labels= “right”]

[fx] No, that’s not correct. Please try again.

[f*] Correct!

[l] heredity

[fx] No. Please try again.

[f*] Excellent!

[l] instructions

[f*] Great!

[l] metabolism

[l] membrane

[l] monomers

[l] polymers

[q labels= “top”]Here’s the same table, but with different blanks to fill in.

[l] Abiotic

[l] building

[l] Encapsulate

[l] pass on

[l] perpetuating

[l] reproduction

[q]So, what’s the probability that all of this (or any of this) could happen on its own? That’s the key to understanding the origin of life. How could something as complex as life arise from much less complex non-life? Let’s take it step by step.

4. Abiotic Formation of Monomers: Oparin, Haldane, and The Miller-Urey Experiment

Let’s address the first step in the table you completed above: the abiotic creation of monomers.

NASA’s working definition of life defines it as a “self-sustaining chemical system capable of Darwinian evolution.”  All living things on Earth are built of four types of molecules: nucleic acids, proteins, lipids, and carbohydrates. Each class of molecule (lipids excepted) is a type of polymer, composed of simpler monomers. So, to explain the origin of the first cells, we have to be able to explain the origin of monomers.

All of these monomers have a few traits in common.

• They’re all chemically reduced, high-energy molecules. They’re full of hydrogen atoms, which have highly energetic electrons. Three of the molecules shown are either used directly (ATP) or indirectly (glucose and caprylic acid) to power cellular work.

Today, monomers are made biotically. Plants and other autotrophs (self-feeding organisms) can make all of their monomers from oxidized, low-energy, simple molecules like carbon dioxide and water. Specifically, during photosynthesis plants combine carbon dioxide and water to make the three-carbon sugar G3P (glyceraldehyde 3 phosphate), releasing oxygen as a waste product. This reaction is endergonic: it has a positive ΔG and is powered by solar energy from the sun.

The molecular machinery that underlies photosynthesis is intricate and complex, and it’s an example of what life does: channeling energy and matter in such a way that creates a little current of order in a universe that’s always growing more disorderly. So, what we have to explain is how, in the absence of life , the reduced, high-energy substances that life is made of (the monomers and then the polymers) could come about.

In the 1920s, two scientists, Alexander Oparin and J.B.S. Haldane, independently hypothesized a way that this could happen. Under the conditions that were then thought to have prevailed on the early Earth, they thought that monomers could spontaneously arise. These monomers would accumulate in the early oceans, forming what’s called a primordial or prebiotic soup . This soup would subsequently serve as the source of polymers.

Oparin and Haldane’s thinking was informed by their thinking about the makeup of the early Earth’s atmosphere. They knew, as we know today, that early Earth’s atmosphere would have been oxygen-free (because they knew that molecular oxygen results from photosynthesis). They proposed, instead, that the early atmosphere would be chemically  reducing.  Reducing substances, as opposed to oxidizing substances like oxygen, contain high-energy electrons. Hydrogen gas and methane, for example, are both highly reduced gases. In chemical reactions, they lose electrons, and that loss releases energy. In the case of hydrogen, this type of electron donation can power a fuel cell to create electricity. In the case of methane, the electron donation can power combustion, either in an oven (creating heat) or in a gas-powered turbine (creating electricity).

In an oxidizing atmosphere, the spontaneous direction of chemical reactions is to break down complex molecules into simpler ones, like carbon dioxide and water. Think about what happens to metals in the modern atmosphere. Over time, they rust, which is a type of oxidation. Organic materials, like wood, burn (another type of oxidation). By contrast, Oparin and Haldane thought that in a reducing atmosphere, the opposite would occur. More complex molecules would form from simpler ones. And that, thought Oparin and Haldane is how the first monomers would arise. 

In 1953, this idea, also known as the Oparin-Haldane hypothesis,  was tested by Stanley Miller, who at that time was a 23-year-old graduate student at the University of Chicago. Miller was working with Harold Urey, a winner of the Nobel Prize for chemistry. Their experiment is now known as the Miller-Urey Experiment.   For an atmospheric mix, Miller chose to use the gases that surround the outer, gas giant planets (like Jupiter and Saturn). These planets have highly reducing atmosphere that consists of methane (CH 4 ), molecular hydrogen (H 2 ), water, and ammonia (NH 3 ).

The entire apparatus was a closed, sterile system, with various valves that could be used to vacuum out all air from the system (3), and sample what the system was producing without contaminating it (9). The system contained a water-filled chamber that simulated the ancient ocean (2). A heat source (1) boiled the ocean, creating water vapor that would rise into a chamber that represented the primitive atmosphere (6) with methane (CH 4 ), ammonia (NH 3 ), molecular hydrogen (H 2 ), and water vapor (H 2 O)

The apparatus also contained electrodes (4) which could produce sparks (5), simulating lightning. A condenser (7) cooled the circulating gas. The cooled gas condensed as a liquid in a trap (8), which allowed Miller to see what his apparatus was brewing up.

After five days, Miller stopped the experiment and sampled the contents. To detect what had formed within his apparatus, Miller used a technique called paper chromatography . This involves using solvents that rise up a paper column, carrying with them dissolved substances, which will rise a known amount in a specific period of time. You can see the results in the photograph Miller published in his May 1953 paper, which was entitled  “ A Production of Amino Acids under Possible Primitive Earth Conditions ” (click the previous link to read: it’s only two pages). The specific amino acids Miller detected were  aspartic acid, glycine, alpha and beta-alanine, and α-aminobutyric acid.  Abiotic synthesis of monomers seemed to have been confirmed, and Miller’s experiment was widely reported in the press.

It turns out that Miller might have been more successful than even he knew. In 2007, the year Miller died, preserved results of his earliest experiments (his work from 1953, and in subsequent years)  were reanalyzed. It was found that Miller’s spark-chamber experiments had yielded not five amino acids, but thirty-one , along with 12 dipeptides (two amino acids linked together by a peptide bond). Source: “ One of the Foremost Experiments of the Twentieth Century. ”

On the other hand, Miller’s work has been criticized for using an atmospheric mix that was too reducing, and thus too conducive to the formation of organic compounds. The Earth’s ancient atmosphere probably didn’t have significant amounts of molecular hydrogen or methane. But Miller’s work inspired many other experiments, which have used different mixes of gases, energy sources, and minerals (such as iron), and have resulted in the production of the nitrogenous bases found in RNA and DNA (though not complete nucleotides) and a wide array of other amino acids.

In addition, amino acids and nucleotide bases have been found inside meteorites (which form out in space) and have also been detected in comets. This includes the Murchison meteorite, which landed in Australia in 1969 and was subject to chemical analysis. What’s the takeaway? It seems probable that within a few hundred million years of the Earth’s cooling, some of the monomers that would make up the polymers within the first living organisms might have spontaneously formed.

We’ll look at scenarios for polymer formation in the next tutorial. But first, let’s consolidate our understanding of the Oparin-Haldane hypothesis and the Miller-Urey experiment.

5. The Miller Urey Experiment: Checking Understanding

[qwiz random = “true” qrecord_id=”sciencemusicvideosMeister1961-Miller-Urey Experiment”]

[h]The Miller-Urey Experiment and Monomer Formation.

[q] In the Miller-Urey experiment, which number represents part that simulated the ancient oceans? [textentry single_char=”true”] [c]ID I=

[f]IEV4Y2VsbGVudC4gTnVtYmVyIDIgcmVwcmVzZW50cyB0aGUgd2F0ZXIgaW4gdGhlIGFuY2llbnQgb2NlYW5zLg==[Qq]

[c]ICo=[Qq]

[f]Tm8uIEhlcmUmIzgyMTc7cyBhIGhpbnQuIFdoaWNoIHBhcnQgbG9va3MgbGlrZSBpdCB3b3VsZCBjb250YWluIHdhdGVyPw==[Qq]

[q] In the Miller-Urey experiment, which number represents a part that simulated lightning in the ancient atmosphere? [textentry single_char=”true”] [c]ID U=

[f]IE5pY2Ugam9iLiBOdW1iZXIgNSByZXByZXNlbnRzIGxpZ2h0bmluZyBpbiB0aGUgYW5jaWVudCBhdG1vc3BoZXJlLg==[Qq]

[f]Tm8uIEhlcmUmIzgyMTc7cyBhIGhpbnQuIFdoaWNoIHBhcnQgbG9va3MgbGlrZSBpdCB3b3VsZCByZXByZXNlbnQgYW4gZWxlY3RyaWNhbCBzcGFyaz8=[Qq]

[q] In the Miller-Urey experiment, which number represents a part that simulated heat from volcanoes? [textentry single_char=”true”] [c]ID E=

[f]IEdvb2Qgd29yay4gTnVtYmVyIDEgcmVwcmVzZW50cyBoZWF0IGZyb20gYW5jaWVudCB2b2xjYW5vZXMu[Qq]

[f]Tm8uIEhlcmUmIzgyMTc7cyBhIGhpbnQuIFdoaWNoIHBhcnQgbG9va3MgbGlrZSBpdCB3b3VsZCBwcm9kdWNlIGhlYXQ/[Qq]

[q] In the diagram below of the Miller-Urey experiment, the electrodes that produce the lighting are represented by which number? [textentry single_char=”true”] [c]ID Q=

[f]V2F5IHRvIGdvLiBOdW1iZXIgNCByZXByZXNlbnRzIHRoZSBzcGFyay1wcm9kdWNpbmcgZWxlY3Ryb2Rlcy4=[Qq]

[f]Tm8uIEhlcmUmIzgyMTc7cyBhIGhpbnQuIEVsZWN0cmljaXR5IGhhcyBwb3NpdGl2ZSBhbmQgbmVnYXRpdmUgY2hhcmdlcy4gV2hlcmUgZG8geW91IHNlZSBzeW1ib2xzIHRoYXQgd291bGQgcmVwcmVzZW50IHBsdXMgYW5kIG1pbnVzIGNoYXJnZXM/[Qq]

[q] In the diagram below of the Miller-Urey experiment, the chamber that contains the gases in the ancient atmosphere would be found at which number? [textentry single_char=”true”] [c]Ng ==

[f]Q29ycmVjdC4gTnVtYmVyIDYgcmVwcmVzZW50cyB0aGUgYW5jaWVudCBhdG1vc3BoZXJlLg==[Qq]

[f]Tm8uIEhlcmUmIzgyMTc7cyBhIGhpbnQuIFRoZSBsaWdodGluZyBvY2N1cnMgd2l0aGluIHRoZSBhdG1vc3BoZXJlLg==[Qq]

[q] In the diagram below of the Miller-Urey experiment, the condenser that cooled the gases in the atmosphere, causing whatever was in the atmosphere to precipitate into the trap, is found at which number? [textentry single_char=”true”] [c]Nw ==

[f]TmljZS4gTnVtYmVyIDcgcmVwcmVzZW50cyB0aGUgY29uZGVuc2VyLg==[Qq]

[f]Tm8uIEhlcmUmIzgyMTc7cyBhIGhpbnQuIENvbmRlbnNlcnMgY2lyY3VsYXRlIHdhdGVyIHRoYXQgY2F1c2VzIHZhcG9ycyB0byBjb25kZW5zZS4gRmluZCB3aGVyZSB3YXRlciBpcyBjaXJjdWxhdGluZyBpbiBhbmQgb3V0Lg==[Qq]

[q] In the diagram below of the Miller-Urey experiment, where would amino acids and other organic compounds have been collected? [textentry single_char=”true”] [c]OA ==

[f]TmljZS4gTnVtYmVyIDggcmVwcmVzZW50cyB0aGUgdHJhcCwgYW5kIHRoYXQmIzgyMTc7cyB3aGVyZSBvcmdhbmljIGNvbXBvdW5kcyBsaWtlIGFtaW5vIGFjaWRzIHdvdWxkIHByZWNpcGl0YXRlIGZvciBjb2xsZWN0aW9uLg==[Qq]

[f]Tm8uIEhlcmUmIzgyMTc7cyBhIGhpbnQuIFRoZSB0cmFwIGlzIGJlbmVhdGggdGhlIGNvbmRlbnNlci4=[Qq]

[q]In the Miller-Urey experiment, the mixture of gases used in the experiment differed from the gases in the current atmosphere in many ways. For one thing, [hangman] (a gas produced by photosynthesis) was lacking.

[c]b3h5Z2Vu[Qq]

[q]Because of the presence of oxygen, today’s atmosphere is oxidizing. In the Oparin-Haldane hypothesis, the atmosphere is thought to be [hangman].

[c]cmVkdWNpbmc=[Qq]

[q]The Miller-Urey experiment was designed to prove that [hangman] synthesis of monomers might have been possible on the early Earth

[c]YWJpb3RpYw==[Qq]

[q]According to the Oparin-Haldane hypothesis, the abiotic synthesis of monomers would result in the creation of a [hangman] soup, in which life would subsequently emerge.

[c]cHJpbW9yZGlhbA==[Qq]

[x] [restart]

• Problematic soup and Alkaline hydrothermal vents
• Origin of Life Menu

Stanley Miller’s Landmark Experiment on the Origin of Life

Stanley Miller (1930 – 2007)

On March 7 , 1930 , American chemist Stanley Lloyd Miller was born. Miller made landmark experiments in the origin of life by demonstrating that a wide range of vital organic compounds can be synthesized by fairly simple chemical processes from inorganic substances . In 1952 he carried out the Miller–Urey experiment , which showed that complex organic molecules could be synthesized from inorganic precursors . The experiment was widely reported, and provided support for the idea that the chemical evolution of the early Earth had led to the natural synthesis of chemical building blocks of life from inanimate inorganic molecules .

Youth and Education

Stanley Miller was born in Oakland, California, as the second child of Nathan and Edith Miller, descendants of Jewish immigrants from Belarus and Latvia. His father was an attorney and held the office of the Oakland Deputy District Attorney and his mother was a school teacher.  Miller attended the University of California at Berkeley studying chemistry and graduated in 1951. Miller then registered for Berkeley’s PhD program and while searching for a decent research topic, Miller talked to many professors, and was initially convinced to work together with Edward Teller in theoretical physics.[ 4 ] However, Miller later attended a lecture by Harold Urey  [ 5 ] who talked about the origin of solar system and how organic synthesis could be possible under reducing environment such as the primitive Earth’s atmosphere . This event sparked Stanley Miller’s enthusiasm for the topic. It is believed that Miller’s work with Teller was not as fruitful as hoped and due to the prospect of Teller leaving Chicago to work on the hydrogen bomb , Miller approached Harold Urey in 1952 for a research project.

The Famous Urey-Miller Experiment

Even though Urey favoured Stanley Miller to work on thallium in meteorites instead of pre-biotic synthesis, Miller persuaded Urey to pursue electric discharges in gases . As a result of their work, the famous Miller-Urey experiment was performed in 1952. The Miller-Urey chemical experiment simulated the conditions thought at the time to be present on the early Earth, and tested the chemical origin of life under those conditions. It confirmed Alexander Oparin ‘s and John Burdon Sanderson Haldane ‘s [ 6 ] earlier hypothesis that putative conditions on the primitive Earth favoured chemical reactions that synthesized more complex organic compounds from simpler inorganic precursors.

In 1953, the Urey-Miller experiment appeared in Science and has become a textbook definition of the scientific basis of origin of life. The scientists designed to simulate the ocean-atmospheric condition of the primitive Earth by using a continuous run of steam into a mixture of methane , ammonia , and hydrogen . When the mixture was exposed to electrical discharge , a chemical reaction was induced. Miller was able to detect the formation of amino acids , such as glycine , α- and β-alanine , using paper chromatography . Miller further detected aspartic acid and gamma-amino butyric acid, however, was not so confident about these.

Further Academic Career

After completing a doctorate in 1954, Miller moved to the California Institute of Technology as a F. B. Jewett Fellow in 1954 and 1955. Here he worked on the mechanism involved in the amino and hydroxy acid synthesis. He then joined the Department of Biochemistry at the College of Physicians and Surgeons, Columbia University , New York , where he worked for the next 5 years. When the new University of California at San Diego was established, he became the first Assistant Professor in the Department of Chemistry in 1960, and an Associate Professor in 1962, and then a full Professor in 1968. Throughout the years he improved the details and methods and was successful in synthesizing more and more varieties of amino acids and producing a wide variety of inorganic and organic compounds essential for cellular construction and metabolism.

Miller suffered a series of strokes beginning in November, 1999 that increasingly inhibited his physical activity. He was living in a nursing home in National City, south of San Diego, and died on 20 May 2007.

References and Further Reading:

• [1]  Stanley Miller at The Scientist
• [2]  Stanley Miller at Britannica
• [3]  Bada JL, Lazcano A.  Stanley L. Miller (1930-2007): A Biographical Memoir . National Academy of Sciences (USA). pp. 1–40.
• [4]  Edward Teller and Stanley Kubrick’s Dr. Strangelove , SciHi Blog, January 15, 2018.
• [5] Harold Urey and the famous Miller–Urey experiment , SciHi Blog, April 29, 2016.
• [6] , J. B. S. Haldane and population Genetics , SciHi Blog, November 5, 2017.
• [7] Stanley Lloyd Miller at Wikidata
• [8]  Harold Urey lecturing at UCLA 4/10/1968 , UCLACommStudies @ youtube
• [9]  Chi KR (24 May 2007).  “Stanley L. Miller dies” .  The Scientist .  
• [10] Timeline of Biopoiesis, i.e. Research on the Origins of Life , via DBpedia and Wikidata

Tabea Tietz

Related posts, sidney fox and his research for the origins of life, frederick william twort and the bacteriophages, wilhelm pfeffer – a pioneer of plant physiology, edward c. kendall and the adrenal cortex hormones, one comment.

Pingback: Whewell’s Gazette: Year 3, Vol. #30 | Whewell's Ghost

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Further Projects

• February (28)
• January (30)
• December (30)
• November (29)
• October (31)
• September (30)
• August (30)
• January (31)
• December (31)
• November (30)
• August (31)
• February (29)
• February (19)
• January (18)
• October (29)
• September (29)
• February (5)
• January (5)
• December (14)
• November (9)
• October (13)
• September (6)
• August (13)
• December (3)
• November (5)
• October (1)
• September (3)
• November (2)
• September (2)

Legal Notice

• Privacy Statement

• History & Society
• Science & Tech
• Biographies
• Animals & Nature
• Geography & Travel
• Arts & Culture
• Games & Quizzes
• On This Day
• One Good Fact
• New Articles
• Lifestyles & Social Issues
• Philosophy & Religion
• Politics, Law & Government
• World History
• Health & Medicine
• Browse Biographies
• Birds, Reptiles & Other Vertebrates
• Bugs, Mollusks & Other Invertebrates
• Environment
• Fossils & Geologic Time
• Entertainment & Pop Culture
• Sports & Recreation
• Visual Arts
• Demystified
• Image Galleries
• Infographics
• Top Questions
• Britannica Kids
• Saving Earth
• Space Next 50
• Student Center

Oparin-Haldane theory

Our editors will review what you’ve submitted and determine whether to revise the article.

Oparin-Haldane theory , idea that organic molecules could be formed from abiogenic materials in the presence of an external energy source—e.g.,  ultraviolet radiation —and that Earth’s primitive atmosphere was reducing (having very low amounts of free  oxygen ) and contained  ammonia  and water vapour, among other gases. The theory emerged in the 1920s, when British scientist  J.B.S. Haldane  and Russian biochemist  Aleksandr Oparin  independently set forth similar ideas concerning the conditions required for the origin of life on Earth .

Haldane and Oparin both suspected that the first life-forms appeared in the warm, primitive ocean and were heterotrophic (obtaining preformed nutrients from the compounds in existence on early Earth) rather than autotrophic (generating food and nutrients from sunlight or inorganic materials). Oparin thought that life developed from coacervates, microscopic spontaneously formed spherical aggregates of  lipid  molecules that are held together by electrostatic forces and that may have been precursors of  cells . Oparin’s work with coacervates confirmed that  enzymes  fundamental for the biochemical reactions of  metabolism  functioned more efficiently when contained within membrane-bound spheres than when free in aqueous solutions. Haldane, unfamiliar with Oparin’s coacervates, thought that simple organic molecules formed first and in the presence of ultraviolet light became increasingly complex, ultimately forming cells. Haldane and Oparin’s ideas formed the foundation for much of the research on abiogenesis that took place in later decades.

In 1953 American chemists  Harold C. Urey  and  Stanley Miller tested the Oparin-Haldane theory and successfully produced organic molecules from some of the inorganic components thought to have been present on prebiotic Earth. This became known as the Miller-Urey experiment . Modern abiogenesis hypotheses are based largely on the same principles as the Oparin-Haldane theory and the Miller-Urey experiment. Subtle differences exist, however, between the several models that have been set forth, and explanations differ as to whether complex organic molecules first became self-replicating entities lacking metabolic functions or first became metabolizing protocells that then developed the ability to self-replicate.

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

• View all journals
• Explore content
• About the journal
• Publish with us
• Sign up for alerts
• Published: August 2007

Stanley Miller 1930–2007

• Michael P Robertson 1  

Nature Chemical Biology volume  3 ,  page 437 ( 2007 ) Cite this article

5288 Accesses

101 Altmetric

Metrics details

During the 1993 meeting of the International Society for the Study of the Origin of Life in Barcelona, Spain, a local newspaper proclaimed the attendance of el padre de la química prebiòtica —the father of prebiotic chemistry—referring to Stanley Lloyd Miller. The title was dramatic, but not inappropriate. Forty years earlier, as a 23-year-old graduate student, Miller had shocked both the scientific community and society as a whole with his demonstration that organic biomolecules could be synthesized in a laboratory simulation of the primitive Earth. In the years following his landmark experiment, Miller continued to be a leader and innovator in the study of the origin of life and surely had earned the venerable title.

Stanley Miller was born in Oakland, California, and earned his bachelor's degree in chemistry at the University of California, Berkeley, before attending the University of Chicago for his doctoral studies. It was in Chicago that Miller would perform the experiments that would shape his career, despite an initial preference for theory over 'messy' and 'time-consuming' experiments. Following a one-year postdoctoral fellowship at the California Institute of Technology, Miller joined the faculty of Columbia University in 1955. In 1960 he was recruited by his mentor Harold Urey to the brand-new San Diego campus of the University of California, where he spent the remainder of his career until his death on 20 May 2007.

The story of Miller's defining achievement begins in 1951, when, as a new graduate student at the University of Chicago, Miller attended a lecture given by Harold Urey on the subject of the origin of the solar system. Urey described the conditions under which Earth and the other planets would have formed and suggested an outline for the conditions under which life presumably had arisen. Theories for the origin of life, in 1951 and still today, can be partitioned into two broad competing philosophies: autotrophy and heterotrophy. An autotrophic organism is characterized by its ability to grow and reproduce by synthesizing everything it needs, requiring only the most basic inorganic materials and an energy source, such as sunlight or various gradients. In contrast, heterotrophic organisms are simpler because they do not rely on making all of their nutrients themselves, but instead must scavenge some of their complex organic building blocks from the environment. Heterotrophy, articulated most famously with Darwin's suggestion that life arose from a 'warm little pond', had long been a familiar concept, but this begged the question of where the building blocks for life—amino acids, nucleic acid bases and sugars, among others—would have come from. Urey believed that for the origin of life to be most plausible, these biological starting materials should have been formed as the result of relatively robust and likely natural processes. These ideas intrigued Miller, and he eventually approached Urey with the proposal of studying the abiotic synthesis of organic biomolecules under prebiotic conditions for his thesis project.

The now-famous Miller-Urey experiment was designed to simulate the conditions of the primitive Earth as they were understood at the time. A sealed glass apparatus was constructed with two hollow spheres in a closed circuit of tubing. One sphere contained water and could be heated to simulate the Earth's oceans. It was connected to a second sphere that represented the Earth's atmosphere, and in the original experiment was filled with a reducing mixture of gases based on Urey's model of the early Earth. The circuit was completed by a trap between the 'atmosphere' and the 'ocean' to condense volatile materials from the 'atmosphere' and 'rain' them into the 'ocean'. The experiment was initiated with the addition of an energy source in the form of a spark discharge between two electrodes in the 'atmosphere' to simulate lightning. When the 'lightning' was turned on in Miller's experiment, the colorless, gaseous starting materials, over the course of days, gave rise to a rich and complex mixture of organic molecules that turned the experiment's 'ocean' yellow and deposited a sticky, tar-like substance on the walls of the atmosphere flask. In Miller's analysis of the products, he found large amounts of several amino acids, one of the main types of building blocks for life. The experiment was a success beyond anyone's expectations, and the discovery, published in Science in 1953, was considered shocking and amazing. The implications were tremendous in the context of the heterotrophic model of life's origin because the fundamental components for the assembly of living systems, rather than being specialized, rare molecules, would have been produced in large quantities as a consequence of natural processes and, because of availability, would have promoted their assimilation into the substance of life. The discovery captivated the imaginations of scientists and nonscientists alike, and fueled a new era of origins-related research that continues to this day.

Miller continued for the rest of his career to contribute important advances along with a standard of careful research, insightful dialog and leadership in the field of prebiotic chemistry that he had helped create. He continued to investigate the prebiotic syntheses of amino acids and helped match the amino acid signatures found in fallen meteorites to that of spark-discharge experiments, showing that this prebiotic synthesis process had occurred at least somewhere in our own solar system. Miller also focused on the components of nucleic acids, vitamins and coenzymes, and placed constraints on the set of likely conditions at the origin of life by carefully studying the decomposition kinetics of biomolecules. And although origins research remained Miller's primary emphasis, he also made fundamental contributions to the study of clathrate hydrates and the mechanism of general anesthesia.

In recent years, the relevance of Miller's spark-discharge experiment has been questioned by some. Currently favored models for the composition of the primitive atmosphere predict a nearly neutral atmosphere rather than the highly reducing mix of gases used in the Miller-Urey experiment. Spark-discharge experiments performed in those types of neutral atmospheres have traditionally not produced many, if any, detectable amino acids, although a recent report suggests that simply buffering the 'ocean' is sufficient to rescue high levels of amino acid production. Although many questions remain to be answered, it appears that Miller's simulated prebiotic synthesis is robust and quite likely ubiquitous in the universe. But beyond the specific details of Miller's discovery, most importantly, it transformed origins-of-life research from a largely theoretical to an experimental science, and an explosion of data and ideas has blossomed in the decades that have followed. A humble and generous mentor, Stanley inspired those around him with his passion and dedication to his science, but those who knew him will also remember his kindness and sense of humor.

Author information

Authors and affiliations.

Michael P. Robertson is at the Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA. [email protected],

Michael P Robertson

You can also search for this author in PubMed   Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article.

Robertson, M. Stanley Miller 1930–2007. Nat Chem Biol 3 , 437 (2007). https://doi.org/10.1038/nchembio0807-437

Download citation

Issue Date : August 2007

DOI : https://doi.org/10.1038/nchembio0807-437

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

Quick links

• Explore articles by subject
• Guide to authors
• Editorial policies

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

May 29, 2007

"Origin of Life Chemist" Stanley Miller

Stanley Miller, who died on May 20, performed one of biology's most famous experiments in 1952, when he showed that simple compounds could form amino acids when zapped with electricity.

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

May 29, 2007  "Origin of Life Chemist" Stanley Miller Stanley Miller died last week. Back in 1952 he performed what has become an iconic experiment in the history of science. One of the big questions concerning the history of life on earth was where did the complex organic compounds come from that all life needs to exist?  Researchers at the time had a pretty good idea that the early earth had ample amounts of hydrogen, water, which is just oxygen and hydrogen, methane, which consists of just carbon and hydrogen, and ammonia, made up of just nitrogen and hydrogen.  Miller put water and ammonia into a flask with methane and hydrogen gas.  He then zapped it with electricity, to approximate the energetic input of lightning strikes and coronal discharges.  When he analyzed the results, the flask of course contained the same elements, nitrogen, carbon, hydrogen and oxygen.  But some very interesting chemistry had taken place.  The breaking of existing chemical bonds and the formation of new ones had turned the starting components into amino acids—the building blocks of protein.  And the now familiar notion of a primordial soup, from which complex biomolecules had sprung, was born.     

AP Biology Question 167: Answer and Explanation

Test information.

Use your browser's back button to return to your test results.

• » Do AP Biology Practice Tests
• » Download AP Biology Practice Tests
• » Best AP Biology Books

More AP Tests

• AP Biology Test 1
• AP Biology Test 2
• AP Biology Test 3
• AP Biology Test 4
• AP Biology Test 5
• AP Biology Test 6
• AP Biology Test 7
• AP Biology Test 8
• AP Biology Test 9
• AP Biology Test 10
• AP Biology Test 11
• AP Biology Test 12
• AP Biology Test 13
• AP Biology Test 14
• AP Biology Test 15
• AP Biology Test 16
• AP Biology Test 17
• AP Biology Test 18
• AP Biology Test 19
• AP Biology Test 20
• AP Biology Test 21
• AP Biology Test 22
• AP Biology Test 23
• AP Biology Test 24
• AP Biology Test 25
• AP Biology Test 26
• AP Biology Test 27
• AP Biology Test 28
• AP Biology Test 29
• AP Biology Test 30
• AP Biology Test 31
• AP Biology Test 32
• AP Biology Test 33
• AP Biology Test 34
• AP Biology Test 35
• AP Biology Test 36
• AP Biology Test 37
• AP Biology Test 38
• AP Biology Test 39
• AP Biology Test 40
• AP Biology Test 41
• AP Biology Test 42

Question: 167

12. In 1953, Stanley Miller, while working under the guidance of Harold Urey at the University of Chicago, carried out a series of experiments with substances that mimicked those of early Earth. His experimental setup yielded a variety of amino acids that are found in organisms alive on Earth today. The purpose of these experiments best supports which of the following hypotheses?

• A. The basic building blocks of life originated in outer space and came to Earth carried by comets or meteorites.
• B. The molecules necessary for life to develop were located in deep-sea vents.
• C. The molecules necessary for life to develop could have formed under the conditions of the early Earth.
• D. The molecules necessary for life on Earth were self-replicating proteins, just like the ones produced in Miller's experiments.

Correct Answer: C

Explanation:

(C) Some scientists believe that some complex molecules necessary for life on Earth might have come from outer space. That might be true. However, the purpose of Miller's experiment was to demonstrate that the molecules necessary for life to develop could have formed under the conditions of the early Earth. He did not succeed in demonstrating that the first molecules were self-replicating.

• Biology Article

Miller Urey Experiment

Miller and urey experiment.

Stanley L. Muller and Harold C. Urey performed an experiment to describe the origin of life on earth. They were of the idea that the early earth’s atmosphere was able to produce amino acids from inorganic matter. The two biologists made use of methane, water, hydrogen, and ammonia which they considered were found in the early earth’s atmosphere. The chemicals were sealed inside sterile glass tubes and flasks connected together in a loop and circulated inside the apparatus.

One flask is half-filled with water and the other flask contains a pair of electrodes. The water vapour was heated and the vapour released was added to the chemical mixture. The released gases circulated around the apparatus imitating the earth’s atmosphere. The water in the flask represents the water on the earth’s surface and the water vapour is just like the water evaporating from lakes, and seas. The electrodes were used to spark the fire to imitate lightning and storm through water vapour.

The vapours were cooled and the water condensed. This condensed water trickles back into the first water flask in a continuous cycle. Miller and Urey examined the cooled water after a week and observed that 10-15% of the carbon was in the form of organic compounds. 2% of carbon had formed 13 amino acids . Yet, the Miller and Urey experiments were condemned by their fellow scientists.

Also read: Origin Of Life

Criticism of the Miller Urey Experiment

The experiment failed to explain how proteins were responsible for the formation of amino acids. A few scientists have contradicted that the gases used by Miller and Urey are not as abundant as shown in the experiment. They were of the notion that the gases released by the volcanic eruptions such as oxygen, nitrogen, and carbon dioxide make up the atmosphere. Therefore, the results are not reliable.

Oparin and Haldane

In the early 20th century, Oparin and Haldane suggested that if the atmosphere of the primitive earth was reducing and if it had sufficient supply of energy such as ultraviolet radiations and lightning, organic compounds would be synthesized at a wide range.

Oparin believed that the organic compounds would have undergone a series of reactions to form complex molecules. He suggested that the molecules formed coacervates in the aqueous environment.

Haldane proposed that the atmosphere of the primordial sea was devoid of oxygen, and was a composed of ammonia, carbon dioxide, and ultraviolet light. This gave rise to a host of organic compounds. The sea contained large amounts of organic monomers and polymers, and the sea was called a ‘hot dilute soup’. He conceived that the polymers and monomers acquired lipid membranes. The molecules further developed and gave rise to the first living organism. ‘Prebiotic soup’ was the term coined by Haldane.

Also read: Evolution of Life on Earth

For more information on the Miller Urey Experiment, visit BYJU’S Biology website, or go to BYJU’S app.

Further Reading:

• Genetic Drift
• Vestigial Organs
• Biogenetic Law
• Biosafety Issues
• Mass Extinctions

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button Check your score and answers at the end of the quiz

Visit BYJU’S for all Biology related queries and study materials

Your result is as below

Request OTP on Voice Call

Leave a Comment Cancel reply

Your Mobile number and Email id will not be published. Required fields are marked *

Post My Comment

Register with BYJU'S & Download Free PDFs

Register with byju's & watch live videos.