Search This Blog

Monday, August 4, 2014

Linus Pauling

Linus Pauling

Condensed from Wikipedia, the free encyclopedia
   
Linus Pauling
L Pauling.jpg
BornLinus Carl Pauling
(1901-02-28)February 28, 1901
Portland, Oregon, USA
DiedAugust 19, 1994(1994-08-19) (aged 93)
Big Sur, California, USA
ResidenceUnited States
NationalityAmerican
Fields
InstitutionsAs faculty member
Caltech (1927–1963)
UC San Diego (1967–1969)
Stanford (1969–1975)
As fellow
Center for the Study of Democratic Institutions (1963–1967)
Alma mater
ThesisThe Determination with X-Rays of the Structures of Crystals (1925[1])
Doctoral advisorRoscoe Dickinson
Richard Tolman[2]
Other academic advisorsArnold Sommerfeld[3]
Niels Bohr[3]
Doctoral studentsMartin Karplus
Jerry Donohue
Matthew Meselson
Edgar Bright Wilson
William Lipscomb[2]
Known for
Notable awards
Signature
Notes
The only person to win two unshared Nobel Prizes.
 
Linus Carl Pauling (February 28, 1901 – August 19, 1994)[4] was an American chemist, biochemist, peace activist, author, and educator. He was one of the most influential chemists in history and ranks among the most important scientists of the 20th century.[5][6] Pauling was one of the founders of the fields of quantum chemistry and molecular biology.[7]
 
For his scientific work, Pauling was awarded the Nobel Prize in Chemistry in 1954. In 1962, for his peace activism, he was awarded the Nobel Peace Prize. This makes him the only person to be awarded two unshared Nobel Prizes. He is one of only four individuals to have won more than one Nobel Prize (the others being Marie Curie, John Bardeen, and Frederick Sanger). Pauling is also one of only two people to be awarded Nobel Prizes in different fields, the other being Marie Curie.[8]
 
 

Career

Pauling was first exposed to the concepts of quantum mechanics while studying at Oregon State University. He later traveled to Europe on a Guggenheim Fellowship, which was awarded to him in 1926, to study under German physicist Arnold Sommerfeld in Munich, Danish physicist Niels Bohr in Copenhagen and Austrian physicist Erwin Schrödinger in Zürich. All three were experts in the new field of quantum mechanics and other branches of physics. Pauling became interested in how quantum mechanics might be applied in his chosen field of interest, the electronic structure of atoms and molecules. In Zürich, Pauling was also exposed to one of the first quantum mechanical analyses of bonding in the hydrogen molecule, done by Walter Heitler and Fritz London. Pauling devoted the two years of his European trip to this work and decided to make it the focus of his future research. He became one of the first scientists in the field of quantum chemistry and a pioneer in the application of quantum theory to the structure of molecules. He also joined Alpha Chi Sigma, the professional chemistry fraternity.
 
In 1927, Pauling took a new position as an assistant professor at Caltech in theoretical chemistry. He launched his faculty career with a very productive five years, continuing with his X-ray crystal studies and also performing quantum mechanical calculations on atoms and molecules. He published approximately fifty papers in those five years, and created the five rules now known as Pauling's rules. By 1929, he was promoted to associate professor, and by 1930, to full professor. In 1931, the American Chemical Society awarded Pauling the Langmuir Prize for the most significant work in pure science by a person 30 years of age or younger.[36] The following year, Pauling published what he regarded as his most important paper, in which he first laid out the concept of hybridization of atomic orbitals and analyzed the tetravalency of the carbon atom.[37]
 
At Caltech, Pauling struck up a close friendship with theoretical physicist Robert Oppenheimer, who was spending part of his research and teaching schedule away from U.C. Berkeley at Caltech every year. The two men planned to mount a joint attack on the nature of the chemical bond: apparently Oppenheimer would supply the mathematics and Pauling would interpret the results. Their relationship soured when Pauling began to suspect that Oppenheimer was becoming too close to his wife, Ava Helen. Once, when Pauling was at work, Oppenheimer had come to their place and blurted out an invitation to Ava Helen to join him on a tryst in Mexico.[38] She flatly refused, and reported the incident to Pauling. Disquieted by this strange chemistry, and her apparent nonchalance about the incident, he immediately cut off his relationship with Oppenheimer.
 
In the summer of 1930, Pauling made another European trip, during which he learned about the use of electrons in diffraction studies similar to the ones he had performed with X-rays. After returning, he built an electron diffraction instrument at Caltech with a student of his, L. O. Brockway, and used it to study the molecular structure of a large number of chemical substances.
 
Pauling introduced the concept of electronegativity in 1932. Using the various properties of molecules, such as the energy required to break bonds and the dipole moments of molecules, he established a scale and an associated numerical value for most of the elements – the Pauling Electronegativity Scale – which is useful in predicting the nature of bonds between atoms in molecules.

Nature of the chemical bond

In the late 1920s Pauling began publishing papers on the nature of the chemical bond, leading to his famous textbook on the subject published in 1939. It is based primarily on his work in this area that he received the Nobel Prize in Chemistry in 1954 "for his research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances". Pauling summarized his work on the chemical bond in The Nature of the Chemical Bond, one of the most influential chemistry books ever published.[39] In the 30 years after its first edition was published in 1939, the book was cited more than 16,000 times. Even today, many modern scientific papers and articles in important journals cite this work, more than seventy years after the first publication.
 
Part of Pauling's work on the nature of the chemical bond led to his introduction of the concept of orbital hybridization.[40] While it is normal to think of the electrons in an atom as being described by orbitals of types such as s and p, it turns out that in describing the bonding in molecules, it is better to construct functions that partake of some of the properties of each. Thus the one 2s and three 2p orbitals in a carbon atom can be combined to make four equivalent orbitals (called sp3 hybrid orbitals), which would be the appropriate orbitals to describe carbon compounds such as methane, or the 2s orbital may be combined with two of the 2p orbitals to make three equivalent orbitals (called sp2 hybrid orbitals), with the remaining 2p orbital unhybridized, which would be the appropriate orbitals to describe certain unsaturated carbon compounds such as ethylene. Other hybridization schemes are also found in other types of molecules.
 
Another area which he explored was the relationship between ionic bonding, where electrons are transferred between atoms, and covalent bonding, where electrons are shared between atoms on an equal basis. Pauling showed that these were merely extremes, between which most actual cases of bonding fall. It was here especially that Pauling's electronegativity concept was particularly useful; the electronegativity difference between a pair of atoms will be the surest predictor of the degree of ionicity of the bond.[41]
 
The third of the topics that Pauling attacked under the overall heading of "the nature of the chemical bond" was the accounting of the structure of aromatic hydrocarbons, particularly the prototype, benzene.[42] The best description of benzene had been made by the German chemist Friedrich Kekulé. He had treated it as a rapid interconversion between two structures, each with alternating single and double bonds, but with the double bonds of one structure in the locations where the single bonds were in the other. Pauling showed that a proper description based on quantum mechanics was an intermediate structure which was a blend of each. The structure was a superposition of structures rather than a rapid interconversion between them. The name "resonance" was later applied to this phenomenon.[43] In a sense, this phenomenon resembles that of hybridization, described earlier, because it involves combining more than one electronic structure to achieve an intermediate result.

Biological molecules


An alpha helix in ultra-high-resolution electron density contours, with O atoms in red, N atoms in blue, and hydrogen bonds as green dotted lines (PDB file 2NRL, 17-32).
 
In the mid-1930s, Pauling, strongly influenced by the biologically oriented funding priorities of the Rockefeller Foundation's Warren Weaver, decided to strike out into new areas of interest. Although Pauling's early interest had focused almost exclusively on inorganic molecular structures, he had occasionally thought about molecules of biological importance, in part because of Caltech's growing strength in biology. Pauling interacted with such great biologists as Thomas Hunt Morgan, Theodosius Dobzhanski, Calvin Bridges and Alfred Sturtevant. His early work in this area included studies of the structure of hemoglobin. He demonstrated that the hemoglobin molecule changes structure when it gains or loses an oxygen atom. As a result of this observation, he decided to conduct a more thorough study of protein structure in general. He returned to his earlier use of X-ray diffraction analysis. But protein structures were far less amenable to this technique than the crystalline minerals of his former work. The best X-ray pictures of proteins in the 1930s had been made by the British crystallographer William Astbury, but when Pauling tried, in 1937, to account for Astbury's observations quantum mechanically, he could not.
 
It took eleven years for Pauling to explain the problem: his mathematical analysis was correct, but Astbury's pictures were taken in such a way that the protein molecules were tilted from their expected positions. Pauling had formulated a model for the structure of hemoglobin in which atoms were arranged in a helical pattern, and applied this idea to proteins in general.
 
In 1951, based on the structures of amino acids and peptides and the planar nature of the peptide bond, Pauling, Robert Corey and Herman Branson correctly proposed the alpha helix and beta sheet as the primary structural motifs in protein secondary structure.[44] This work exemplified Pauling's ability to think unconventionally; central to the structure was the unorthodox assumption that one turn of the helix may well contain a non-integer number of amino acid residues; for the alpha helix it is 3.7 amino acid residues per turn.
 
Pauling then proposed that deoxyribonucleic acid (DNA) was a triple helix;[45][46] his model contained several basic mistakes, including a proposal of neutral phosphate groups, an idea that conflicted with the acidity of DNA. Sir Lawrence Bragg had been disappointed that Pauling had won the race to find the alpha helix structure of proteins. Bragg's team had made a fundamental error in making their models of protein by not recognizing the planar nature of the peptide bond. When it was learned at the Cavendish Laboratory that Pauling was working on molecular models of the structure of DNA, James Watson and Francis Crick were allowed to make a molecular model of DNA. They later benefited from unpublished data from Maurice Wilkins and Rosalind Franklin at King's College which showed evidence for a helix and planar base stacking along the helix axis. Early in 1953 Watson and Crick proposed a correct structure for the DNA double helix. Pauling later cited several reasons to explain how he had been misled about the structure of DNA, among them misleading density data and the lack of high quality X-ray diffraction photographs. During the time Pauling was researching the problem, Rosalind Franklin in England was creating the world's best images. They were key to Watson's and Crick's success. Pauling did not see them before devising his mistaken DNA structure, although his assistant Robert Corey did see at least some of them, while taking Pauling's place at a summer 1952 protein conference in England. Pauling had been prevented from attending because his passport was withheld by the State Department on suspicion that he had Communist sympathies. This led to the legend that Pauling missed the structure of DNA because of the politics of the day (this was at the start of the McCarthy period in the United States).[47] Politics did not play a critical role. Not only did Corey see the images at the time, but Pauling himself regained his passport within a few weeks and toured English laboratories well before writing his DNA paper. He had ample opportunity to visit Franklin's lab and see her work, but chose not to.[48]
 
Pauling also studied enzyme reactions and was among the first to point out that enzymes bring about reactions by stabilizing the transition state of the reaction, a view which is central to understanding their mechanism of action. He was also among the first scientists to postulate that the binding of antibodies to antigens would be due to a complementarity between their structures. Along the same lines, with the physicist turned biologist Max Delbrück, he wrote an early paper arguing that DNA replication was likely to be due to complementarity, rather than similarity, as suggested by a few researchers. This was made clear in the model of the structure of DNA that Watson and Crick discovered.

Molecular genetics

In November 1949, Linus Pauling, Harvey Itano, S. J. Singer and Ibert Wells published "Sickle Cell Anemia, a Molecular Disease"[49] in the journal Science. It was the first proof of a human disease caused by an abnormal protein, and sickle cell anemia became the first disease understood at the molecular level. Using electrophoresis, they demonstrated that individuals with sickle cell disease had a modified form of hemoglobin in their red blood cells, and that individuals with sickle cell trait had both the normal and abnormal forms of hemoglobin. This was also the first demonstration that Mendelian inheritance determined the specific physical properties of proteins, not simply their presence or absence – the dawn of molecular genetics.

Activism

Pauling had been practically apolitical until World War II, but the aftermath of the war and his wife's pacifism changed his life profoundly, and he became a peace activist. During the beginning of the Manhattan Project, Robert Oppenheimer invited him to be in charge of the Chemistry division of the project, but he declined, not wanting to uproot his family. He did work on other projects that had military applications, such as explosives, rocket propellants, an oxygen meter for submarines and the patent of an armor-piercing shell; he was awarded a Presidential Medal of Merit.[50][51] In 1946, he joined the Emergency Committee of Atomic Scientists, chaired by Albert Einstein.[52] Its mission was to warn the public of the dangers associated with the development of nuclear weapons. His political activism prompted the U.S. State Department to deny him a passport in 1952, when he was invited to speak at a scientific conference in London.[53][54] In a speech before the US senate on June 6 of the same year, Senator Wayne Morse publicly denounced the action of the State Department, and urged the Passport Division to reverse its decision. Pauling and his wife Ava were issued a “limited passport” to attend the aforementioned conference in England.[55][56] His passport was restored in 1954, shortly before the ceremony in Stockholm where he received his first Nobel Prize. Joining Einstein, Bertrand Russell and eight other leading scientists and intellectuals, he signed the Russell-Einstein Manifesto in 1955.[57]
 
In 1958, Pauling joined a petition drive in cooperation with the founders of the St. Louis Citizen's Committee for Nuclear Information (CNI). This group, headed by Washington University in St. Louis professors Barry Commoner, Eric Reiss, M. W. Friedlander and John Fowler, set up a study of radioactive strontium-90 in the baby teeth of children across North America. The "Baby Tooth Survey," headed by Dr Louise Reiss, demonstrated conclusively in 1961 that above-ground nuclear testing posed significant public health risks in the form of radioactive fallout spread primarily via milk from cows that had ingested contaminated grass.[58][59][60] Pauling also participated in a public debate with the atomic physicist Edward Teller about the actual probability of fallout causing mutations.[61] In 1958, Pauling and his wife presented the United Nations with the petition signed by more than 11,000 scientists calling for an end to the testing of nuclear weapons. Public pressure and the frightening results of the CNI research subsequently led to a moratorium on above-ground nuclear weapons testing, followed by the Partial Test Ban Treaty, signed in 1963 by John F. Kennedy and Nikita Khrushchev. On the day that the treaty went into force, the Nobel Prize Committee awarded Pauling the Nobel Peace Prize, describing him as "Linus Carl Pauling, who ever since 1946 has campaigned ceaselessly, not only against nuclear weapons tests, not only against the spread of these armaments, not only against their very use, but against all warfare as a means of solving international conflicts."[62] The Committee for Nuclear Information was never credited for its significant contribution to the test ban, nor was the ground-breaking research conducted by Dr Reiss and the "Baby Tooth Survey". The Caltech Chemistry Department, wary of his political views, did not even formally congratulate him. They did throw him a small party, showing they were more appreciative and sympathetic toward his work on radiation mutation. At Caltech he founded Sigma Xi's (The Scientific Research Society) chapter at the school, as he had previously been a member of that organization. He continued his peace activism in the following years co-founding the International League of Humanists in 1974. He was president of the scientific advisory board of the World Union for Protection of Life and also one of the signatories of the Dubrovnik-Philadelphia Statement.
During the 1960s, President Lyndon Johnson’s policy of increasing America’s involvement in the Vietnam War caused an antiwar movement that the Paulings joined with enthusiasm. Pauling denounced the war as unnecessary and unconstitutional. He made speeches, signed protest letters and communicated personally with the North Vietnamese leader, Ho Chi Minh, and gave the lengthy written response to President Johnson. His efforts were ignored by the government.[63] By the time Pauling turned 65 in 1966, he was without a research group or a big scientific issue to focus on. A new generation of more radical, younger activists would march, petition, and lead the movement against the Vietnam War.
 
Many of Pauling's critics, including scientists who appreciated the contributions that he had made in chemistry, disagreed with his political positions and saw him as a naive spokesman for Soviet communism. He was ordered to appear before the Senate Internal Security Subcommittee, which termed him "the number one scientific name in virtually every major activity of the Communist peace offensive in this country." A headline in Life magazine characterized his 1962 Nobel Prize as "A Weird Insult from Norway". Pauling was awarded the International Lenin Peace Prize by the USSR in 1970.[64]

Contretemps with William F. Buckley, National Review.

After Pauling had won the Nobel Peace Prize and the Lenin Peace Prize, he became a frequent target of The National Review magazine; particularly, in an article entitled "The Collaborators" in the magazine's July 17, 1962 issue. Pauling was not only referred to as a collaborator, but a "fellow traveler" with proponents of Soviet style communism. These National Review articles set off a three year legal battle in the form of federal libel case. In 1965, Pauling sued the magazine, its publisher William Rusher, and its editor William F. Buckley, Jr for $1 million. Subsequently, he lost both his suit and the 1968 appeal. The loss of both suits and continued attacks by the National Review did nothing to enhance Pauling's reputation. [65] [66] [67] [68]

Molecular medicine, medical research, and vitamin C advocacy


Linus Pauling's book, How to Live Longer and Feel Better, advocated the very high intake of Vitamin C.
 
In 1941, at age 40, Pauling was diagnosed with Bright's disease, a renal disease. Following the recommendations of Thomas Addis, Pauling was able to control the disease with Addis' then unusual low-protein salt-free diet and vitamin supplements.[69]
 
In 1951, Pauling gave a lecture entitled "Molecular Medicine".[70] In the late 1950s, Pauling worked on the role of enzymes in brain function, believing that mental illness may be partly caused by enzyme dysfunction. In 1965 Pauling read Niacin Therapy in Psychiatry by Abram Hoffer and theorized vitamins might have important biochemical effects unrelated to their prevention of associated deficiency diseases.[71] In 1968 Pauling published a brief paper in Science entitled "Orthomolecular psychiatry"[72] that gave name and principle to the popular but controversial megavitamin therapy movement of the 1970s. Pauling coined the term "orthomolecular" to refer to the practice of varying the concentration of substances normally present in the body to prevent and treat disease. His ideas formed the basis of orthomolecular medicine, which is not generally practiced by conventional medical professionals and has been strongly criticized.[73][74] His promotion of dietary supplements has also been criticized. In a 2013 article in The Atlantic, pediatrician Paul Offit wrote that although Pauling was "so spectacularly right" that he won two Nobel Prizes, Pauling's late-career assertions about the benefits of dietary supplements were "so spectacularly wrong that he was arguably the world's greatest quack."[75]
 
Pauling's work on vitamin C in his later years generated much controversy. He was first introduced to the concept of high-dose vitamin C by biochemist Irwin Stone in 1966. After becoming convinced of its worth, Pauling took 3 grams of vitamin C every day to prevent colds.[4] Excited by his own perceived results, he researched the clinical literature and published Vitamin C and the Common Cold in 1970. He began a long clinical collaboration with the British cancer surgeon Ewan Cameron in 1971 on the use of intravenous and oral vitamin C as cancer therapy for terminal patients.[76]
Cameron and Pauling wrote many technical papers and a popular book, Cancer and Vitamin C, that discussed their observations. Pauling made vitamin C popular with the public and eventually published two studies of a group of 100 allegedly terminal patients that claimed vitamin C increased survival by as much as four times compared to untreated patients.[77][78] A re-evaluation of the claims in 1982 found that the patient groups were not actually comparable, with the vitamin C group being less sick on entry to the study, and judged to be "terminal" much earlier than the comparison group.[79]
 
Later clinical trials conducted by the Mayo Clinic also concluded that high-dose (10,000 mg) vitamin C was no better than placebo at treating cancer and that there was no benefit to high-dose vitamin C.[80][81][82] The failure of the clinical trials to demonstrate any benefit resulted in the conclusion that vitamin C was not effective in treating cancer; the medical establishment concluding that his claims that vitamin C could prevent colds or treat cancer were quackery.[4][83] Pauling denounced the conclusions of these studies and handling of the final study as "fraud and deliberate misrepresentation",[84][85] and criticized the studies for using oral, rather than intravenous vitamin C[86] (which was the dosing method used for the first ten days of Pauling's original study[83]). Pauling also criticised the Mayo clinic studies because the controls were taking vitamin C during the trial, and because the duration of the treatment with vitamin C was short; Pauling advocated continued high dose vitamin C for the rest of the cancer patient's life whereas the Mayo clinic patients in the second trial were treated with vitamin C for a median of 2.5 months.[87] The results were publicly debated at length with considerable acrimony between Pauling and Cameron, and Moertel (the lead author of the Mayo Clinic studies), with accusations of misconduct and scientific incompetence on both sides.
Ultimately the negative findings of the Mayo Clinic studies ended general interest in vitamin C as a treatment for cancer.[85] Despite this, Pauling continued to promote vitamin C for treating cancer and the common cold, working with The Institutes for the Achievement of Human Potential to use vitamin C in the treatment of brain-injured children.[88] He later collaborated with the Canadian physician Abram Hoffer on a micronutrient regimen, including high-dose vitamin C, as adjunctive cancer therapy.[89] A 2009 review also noted differences between the studies, such as the Mayo clinic not using intravenous Vitamin C, and suggested further studies into the role of vitamin C when given intravenously.[90] Currently, the available evidence does not support a role for high dose vitamin C in the treatment of cancer.[91]
 
With Arthur B. Robinson and another colleague, Pauling founded the Institute of Orthomolecular Medicine in Menlo Park, California, in 1973, which was soon renamed the Linus Pauling Institute of Science and Medicine. Pauling directed research on vitamin C, but also continued his theoretical work in chemistry and physics until his death. In his last years, he became especially interested in the possible role of vitamin C in preventing atherosclerosis and published three case reports on the use of lysine and vitamin C to relieve angina pectoris. In 1996, the Linus Pauling Institute moved from Palo Alto, California, to Corvallis, Oregon, to become part of Oregon State University, where it continues to conduct research on micronutrients, phytochemicals (chemicals from plants), and other constituents of the diet in preventing and treating disease. Several researchers that had previously worked at the Linus Pauling Institute in Palo Alto, including the assistant director of research, moved on to form the Genetic Information Research Institute.

Structure of the atomic nucleus

On September 16, 1952, Pauling opened a new research notebook with the words "I have decided to attack the problem of the structure of nuclei."[92] On October 15, 1965, Pauling published his Close-Packed Spheron Model of the atomic nucleus in two well respected journals, Science and the Proceedings of the National Academy of Sciences.[93] For nearly three decades, until his death in 1994, Pauling published numerous papers on his spheron cluster model.[94][95][96][97][98][99]
The basic idea behind Pauling's spheron model is that a nucleus can be viewed as a set of "clusters of nucleons". The basic nucleon clusters include the deuteron [np], helion [pnp], and triton [npn]. Even–even nuclei are described as being composed of clusters of alpha particles, as has often been done for light nuclei.[citation needed] Pauling attempted to derive the shell structure of nuclei from pure geometrical considerations related to Platonic solids rather than starting from an independent particle model as in the usual shell model. In an interview given in 1990 Pauling commented on his model:[100]
Now recently, I have been trying to determine detailed structures of atomic nuclei by analyzing the ground state and excited state vibrational bends, as observed experimentally. From reading the physics literature, Physical Review Letters and other journals, I know that many physicists are interested in atomic nuclei, but none of them, so far as I have been able to discover, has been attacking the problem in the same way that I attack it. So I just move along at my own speed, making calculations...

Legacy

Pauling died of prostate cancer on August 19, 1994, at 19:20 at home in Big Sur, California. He was 93 years old.[101][102] A grave marker for him is in Oswego Pioneer Cemetery in Lake Oswego, Oregon.[102][103] Pauling’s ashes, along with those of his wife, were moved from Big Sur to the Oswego Pioneer Cemetery in 2005.[104]
 
Pauling was included in a list of the 20 greatest scientists of all time by the magazine New Scientist, with Albert Einstein being the only other scientist from the 20th century on the list. Pauling is notable for the diversity of his interests: quantum mechanics, inorganic chemistry, organic chemistry, protein structure, molecular biology, and medicine. In all these fields, and especially on the boundaries between them, he made decisive contributions. His work on chemical bonding marks the beginning of modern quantum chemistry, and many of his contributions like hybridization and electronegativity have become part of standard chemistry textbooks. While his valence bond approach fell short of accounting quantitatively for some of the characteristics of molecules, such as the photoelectron spectra of many molecules, and would later be eclipsed by the molecular orbital theory of Robert Mulliken, Valence Bond Theory still competes, in its modern form, with both Molecular Orbital Theory and density functional theory (DFT) for describing the chemical phenomena.[105] Pauling's work on crystal structure contributed significantly to the prediction and elucidation of the structures of complex minerals and compounds.[citation needed] His discovery of the alpha helix and beta sheet is a fundamental foundation for the study of protein structure.[citation needed]
 
Francis Crick acknowledged Pauling as the "father of molecular biology"[106] His discovery of sickle cell anemia as a "molecular disease" opened the way toward examining genetically acquired mutations at a molecular level.[citation needed]
 
Pauling's work on the molecular basis of disease and its treatment is being carried on by a number of researchers, notably those at the Linus Pauling Institute, which lists a dozen principal investigators and faculty who study the role of micronutrients and phytochemicals in health and disease.
Items named after Pauling include Pauling Street in Foothill Ranch, California,[107] Linus Pauling Drive in Hercules, California, Linus and Ava Helen Pauling Hall at Soka University of America in Aliso Viejo, California, Linus Pauling Middle School in Corvallis, Oregon, and Pauling Field, a small airfield located in Condon, Oregon, where Pauling spent his youth. Additionally, the Linus Pauling Institute[108] and also a wing of The Valley Library at Oregon State University bear his name. There is a psychedelic rock band in Houston, Texas, named The Linus Pauling Quartet.
 
The Caltech Chemistry Department renamed room 22 of Gates Hall the Linus Pauling Lecture Hall, since Linus spent so much time there.
 
Linus Torvalds, developer of the Linux kernel, is named after Pauling.[109]
 
On March 6, 2008, the United States Postal Service released a 41 cent stamp honoring Pauling designed by artist Victor Stabin.[110] His description reads: "A remarkably versatile scientist, structural chemist Linus Pauling (1901–1994) won the 1954 Nobel Prize in Chemistry for determining the nature of the chemical bond linking atoms into molecules. His work in establishing the field of molecular biology; his studies of hemoglobin led to the classification of sickle cell anemia as a molecular disease." The other scientists on this sheet include Gerty Cori, biochemist, Edwin Hubble, astronomer, and John Bardeen, physicist.
 
California Governor Arnold Schwarzenegger and First Lady Maria Shriver announced on May 28, 2008 that Pauling would be inducted into the California Hall of Fame, located at The California Museum for History, Women and the Arts. The induction ceremony took place December 15, 2008. Pauling's son was asked to accept the honor in his place.
 
Nobel laureate Peter Agre has said that Linus Pauling inspired him.[111]

Quasicrystals

Pauling was a stubborn opponent of the idea of quasicrystals, relentlessly attacking Shechtman; Pauling is quoted as saying "There is no such thing as quasicrystals, only quasi-scientists."[112] Shechtman was awarded the Nobel Prize in Chemistry in 2011 for his work on quasicrystals.

Honors and awards

Pauling received numerous awards and honors during his career, including the following:[113][114]

Alfred Russel Wallace and Evolution

Alfred Russel Wallace

Condensed from Wikipedia, the free encyclopedia
 
Alfred Russel Wallace
Alfred-Russel-Wallace-c1895.jpg
Born(1823-01-08)8 January 1823
Usk, Monmouthshire, Wales
Died7 November 1913(1913-11-07) (aged 90)
Broadstone, Dorset, England
NationalityBritish
FieldsExploration, evolutionary biology, zoology, biogeography, and social reform
Known forCo-discovery of natural selection
Pioneering work on biogeography
Wallace Line
Wallace effect
Notable awardsRoyal Medal (1868)
Darwin Medal (1890)
Copley Medal (1908)
Gold Medal of the Société de Géographie (1870)
Founder's Medal (1892)
Linnean Medal) (1892)
Darwin-Wallace Medal (Gold, 1908)
Order of Merit (1908)
Author abbrev. (botany)Wallace

Alfred Russel Wallace OM FRS (8 January 1823 – 7 November 1913) was a British naturalist, explorer, geographer, anthropologist, and biologist. He is best known for independently conceiving the theory of evolution through natural selection; his paper on the subject was jointly published with some of Charles Darwin's writings in 1858.[1] This prompted Darwin to publish his own ideas in On the Origin of Species. Wallace did extensive fieldwork, first in the Amazon River basin and then in the Malay Archipelago, where he identified the faunal divide now termed the Wallace Line, which separates the Indonesian archipelago into two distinct parts: a western portion in which the animals are largely of Asian origin, and an eastern portion where the fauna reflect Australasia.

He was considered the 19th century's leading expert on the geographical distribution of animal species and is sometimes called the "father of biogeography".[2] Wallace was one of the leading evolutionary thinkers of the 19th century and made many other contributions to the development of evolutionary theory besides being co-discoverer of natural selection. These included the concept of warning colouration in animals, and the Wallace effect, a hypothesis on how natural selection could contribute to speciation by encouraging the development of barriers against hybridisation.

Wallace was strongly attracted to unconventional ideas (such as evolution). His advocacy of spiritualism and his belief in a non-material origin for the higher mental faculties of humans strained his relationship with some members of the scientific establishment. In addition to his scientific work, he was a social activist who was critical of what he considered to be an unjust social and economic system in 19th-century Britain. His interest in natural history resulted in his being one of the first prominent scientists to raise concerns over the environmental impact of human activity.

Wallace was a prolific author who wrote on both scientific and social issues; his account of his adventures and observations during his explorations in Singapore, Indonesia and Malaysia, The Malay Archipelago, is regarded as probably the best of all journals of scientific exploration published during the 19th century.

Wallace had financial difficulties throughout much of his life. His Amazon and far-eastern trips were supported by the sale of specimens he collected and, after he lost most of the considerable money he made from those sales in unsuccessful investments, he had to support himself mostly from the publications he produced. Unlike some of his contemporaries in the British scientific community, such as Darwin and Charles Lyell, he had no family wealth to fall back on, and he was unsuccessful in finding a long-term salaried position, receiving no regular income until he was awarded a small government pension, through Darwin's efforts, in 1881.

Theory of evolution

Early evolutionary thinking

Unlike Darwin, Wallace began his career as a travelling naturalist already believing in the transmutation of species. The concept had been advocated by Jean-Baptiste Lamarck, Geoffroy Saint-Hilaire, Erasmus Darwin, and Robert Grant, among others. It was widely discussed, but not generally accepted by leading naturalists, and was considered to have radical, even revolutionary connotations.[56][57]

Prominent anatomists and geologists such as Georges Cuvier, Richard Owen, Adam Sedgwick, and Charles Lyell attacked it vigorously.[58][59] It has been suggested that Wallace accepted the idea of the transmutation of species in part because he was always inclined to favour radical ideas in politics, religion and science,[56] and because he was unusually open to marginal, even fringe, ideas in science.[60]

He was also profoundly influenced by Robert Chambers' work Vestiges of the Natural History of Creation, a highly controversial work of popular science published anonymously in 1844 that advocated an evolutionary origin for the solar system, the earth, and living things.[61] Wallace wrote to Henry Bates in 1845:
I have a rather more favourable opinion of the 'Vestiges' than you appear to have. I do not consider it a hasty generalization, but rather as an ingenious hypothesis strongly supported by some striking facts and analogies, but which remains to be proven by more facts and the additional light which more research may throw upon the problem. It furnishes a subject for every student of nature to attend to; every fact he observes will make either for or against it, and it thus serves both as an incitement to the collection of facts, and an object to which they can be applied when collected.[60]
In 1847, he wrote to Bates:
I should like to take some one family [of beetles] to study thoroughly, principally with a view to the theory of the origin of species. By that means I am strongly of opinion that some definite results might be arrived at.[62]
Wallace deliberately planned some of his field work to test the hypothesis that under an evolutionary scenario closely related species should inhabit neighbouring territories.[56] During his work in the Amazon basin, he came to realise that geographical barriers—such as the Amazon and its major tributaries—often separated the ranges of closely allied species, and he included these observations in his 1853 paper "On the Monkeys of the Amazon".[63] Near the end of the paper he asks the question "Are very closely allied species ever separated by a wide interval of country?"

In February 1855, while working in Sarawak on the island of Borneo, Wallace wrote "On the Law which has Regulated the Introduction of New Species", a paper which was published in the Annals and Magazine of Natural History in September 1855.[64] In this paper, he discussed observations regarding the geographic and geologic distribution of both living and fossil species, what would become known as biogeography. His conclusion that "Every species has come into existence coincident both in space and time with a closely allied species" has come to be known as the "Sarawak Law". Wallace thus answered the question he had posed in his earlier paper on the monkeys of the Amazon river basin. Although it contained no mention of any possible mechanisms for evolution, this paper foreshadowed the momentous paper he would write three years later.[65]


The paper shook Charles Lyell's belief that species were immutable. Although his friend Charles
Darwin had written to him in 1842 expressing support for transmutation, Lyell had continued to be strongly opposed to the idea. Around the start of 1856, he told Darwin about Wallace's paper, as did Edward Blyth who thought it "Good! Upon the whole! ... Wallace has, I think put the matter well; and according to his theory the various domestic races of animals have been fairly developed into species." Despite this hint, Darwin mistook Wallace's conclusion for the progressive creationism of the time and wrote that it was "nothing very new ... Uses my simile of tree [but] it seems all creation with him." Lyell was more impressed, and opened a notebook on species, in which he grappled with the consequences, particularly for human ancestry. Darwin had already shown his theory to their mutual friend Joseph Hooker and now, for the first time, he spelt out the full details of natural selection to Lyell. Although Lyell could not agree, he urged Darwin to publish to establish priority. Darwin demurred at first, then began writing up a species sketch of his continuing work in May 1856.[66]

Natural selection and Darwin

By February 1858, Wallace had been convinced by his biogeographical research in the Malay Archipelago of the reality of evolution. As he later wrote in his autobiography:
The problem then was not only how and why do species change, but how and why do they change into new and well defined species, distinguished from each other in so many ways; why and how they become so exactly adapted to distinct modes of life; and why do all the intermediate grades die out (as geology shows they have died out) and leave only clearly defined and well marked species, genera, and higher groups of animals?[67]
According to his autobiography, it was while he was in bed with a fever that Wallace thought about Thomas Malthus's idea of positive checks on human population growth and came up with the idea of natural selection.[68] Wallace said in his autobiography that he was on the island of Ternate at the time; but historians have questioned this, saying that on the basis of the journal he kept at the time, he was on the island of Gilolo.[69] From 1858 to 1861 he rented a house on Ternate from the Dutchman M.D. van Renesse van Duivenbode. He used this house as a base camp for expeditions to other islands such as Gilolo.[70]

Wallace describes how he discovered natural selection as follows:
It then occurred to me that these causes or their equivalents are continually acting in the case of animals also; and as animals usually breed much more quickly than does mankind, the destruction every year from these causes must be enormous in order to keep down the numbers of each species, since evidently they do not increase regularly from year to year, as otherwise the world would long ago have been crowded with those that breed most quickly. Vaguely thinking over the enormous and constant destruction which this implied, it occurred to me to ask the question, why do some die and some live? And the answer was clearly, on the whole the best fitted live ... and considering the amount of individual variation that my experience as a collector had shown me to exist, then it followed that all the changes necessary for the adaptation of the species to the changing conditions would be brought about ... In this way every part of an animals organization could be modified exactly as required, and in the very process of this modification the unmodified would die out, and thus the definite characters and the clear isolation of each new species would be explained.[71]
The Darwin–Wallace Medal was issued by the Linnean society on the 50th anniversary of the reading of Darwin and Wallace's papers on natural selection.

Wallace had once briefly met Darwin, and was one of the correspondents whose observations Darwin used to support his own theories. Although Wallace's first letter to Darwin has been lost, Wallace carefully kept the letters he received.[72] In the first letter, dated 1 May 1857, Darwin commented that Wallace's letter of 10 October which he had recently received, as well as Wallace's paper "On the Law which has regulated the Introduction of New Species" of 1855, showed that they were both thinking alike and to some extent reaching similar conclusions, and said that he was preparing his own work for publication in about two years time.[73] The second letter, dated 22 December 1857, said how glad he was that Wallace was theorising about distribution, adding that "without speculation there is no good and original observation" while commenting that "I believe I go much further than you".[74] Wallace trusted Darwin's opinion on the matter and sent him his February 1858 essay, "On the Tendency of Varieties to Depart Indefinitely From the Original Type", with the request that Darwin would review it and pass it on to Charles Lyell if he thought it worthwhile.[1] Although Wallace had sent several articles for journal publication during his travels through the Malay archipelago, the Ternate essay was in a private letter. On 18 June 1858, Darwin received the essay from Wallace. While Wallace's essay obviously did not employ Darwin's term "natural selection", it did outline the mechanics of an evolutionary divergence of species from similar ones due to environmental pressures. In this sense, it was very similar to the theory that Darwin had worked on for twenty years, but had yet to publish. Darwin sent the manuscript to Charles Lyell with a letter saying "he could not have made a better short abstract! Even his terms now stand as heads of my chapters ... he does not say he wishes me to publish, but I shall, of course, at once write and offer to send to any journal."[75] Distraught about the illness of his baby son, Darwin put the problem to Charles Lyell and Joseph Hooker, who decided to publish the essay in a joint presentation together with unpublished writings which highlighted Darwin's priority. Wallace had not asked for publication of his essay, and indeed, doing so probably contravened the copyright law of the time. Wallace's essay was presented to the Linnean Society of London on 1 July 1858, along with excerpts from an essay which Darwin had disclosed privately to Hooker in 1847 and a letter Darwin had written to Asa Gray in 1857.[76]

Communication with Wallace in far-off Malay was impossible without months of delay, so he was not part of this rapid publication. Fortunately, Wallace accepted the arrangement after the fact, happy that he had been included at all, and never expressed public or private bitterness. Darwin's social and scientific status was far greater than Wallace's, and it was unlikely that, without Darwin, Wallace's views on evolution would have been taken seriously. Lyell and Hooker's arrangement relegated Wallace to the position of co-discoverer, and he was not the social equal of Darwin or the other prominent British natural scientists. However, the joint reading of their papers on natural selection associated Wallace with the more famous Darwin. This, combined with Darwin's (as well as Hooker's and Lyell's) advocacy on his behalf, would give Wallace greater access to the highest levels of the scientific community.[77] The reaction to the reading was muted, with the president of the Linnean remarking in May 1859 that the year had not been marked by any striking discoveries;[78] but, with Darwin's publication of On the Origin of Species later in 1859, its significance became apparent. When Wallace returned to the UK, he met Darwin. Although some of Wallace's iconoclastic opinions in the ensuing years would test Darwin's patience, they remained on friendly terms for the rest of Darwin's life.

Over the years, a few people have questioned this version of events. In the early 1980s, two books, one written by Arnold Brackman and another by John Langdon Brooks, even suggested not only that there had been a conspiracy to rob Wallace of his proper credit, but that Darwin had actually stolen a key idea from Wallace to finish his own theory. These claims have been examined in detail by a number of scholars who have not found them to be convincing.[79][80][81] Research into shipping schedules has shown that, contrary to these accusations, Wallace's letter could not have been delivered earlier than the date shown in Darwin's letter to Lyell.[82] [83]

Defence of Darwin and his ideas

After the publication of Darwin's On the Origin of Species, Wallace became one of its staunchest defenders on his return to England in 1862. In one incident in 1863 that particularly pleased Darwin, Wallace published the short paper "Remarks on the Rev. S. Haughton's Paper on the Bee's Cell, And on the Origin of Species" in order to rebuke a paper by a professor of geology at the University of Dublin that had sharply criticised Darwin's comments in the Origin on how hexagonal honey bee cells could have evolved through natural selection.[84]

An even lengthier defence of Darwin's work was "Creation by Law", a review Wallace wrote in 1867 for The Quarterly Journal of Science of the book The Reign of Law, which had been written by George Campbell, the 8th Duke of Argyll, as a refutation of natural selection.[85] After an 1870 meeting of the British Association, Wallace wrote to Darwin complaining that there were "no opponents left who know anything of natural history, so that there are none of the good discussions we used to have."[86]

Differences between Darwin's and Wallace's ideas on natural selection

Historians of science have noted that, while Darwin considered the ideas in Wallace's paper to be essentially the same as his own, there were differences.[87] Darwin emphasised competition between individuals of the same species to survive and reproduce, whereas Wallace emphasised environmental pressures on varieties and species forcing them to become adapted to their local conditions, leading populations in different locations to diverge.[88][89] Some historians, including Peter J. Bowler, have suggested the possibility that in the paper he mailed to Darwin Wallace was not discussing selection of individual variations at all but rather group selection.[90]

Others have noted that another difference was that Wallace appeared to have envisioned natural selection as a kind of feedback mechanism keeping species and varieties adapted to their environment.[91] They point to a largely overlooked passage of Wallace's famous 1858 paper:
The action of this principle is exactly like that of the centrifugal governor of the steam engine, which checks and corrects any irregularities almost before they become evident; and in like manner no unbalanced deficiency in the animal kingdom can ever reach any conspicuous magnitude, because it would make itself felt at the very first step, by rendering existence difficult and extinction almost sure soon to follow.[1]
The cybernetician and anthropologist Gregory Bateson would observe in the 1970s that, though writing it only as an example, Wallace had "probably said the most powerful thing that'd been said in the 19th Century".[92] Bateson revisited the topic in his 1979 book Mind and Nature: A Necessary Unity, and other scholars have continued to explore the connection between natural selection and systems theory.[91]

Warning colouration and sexual selection

In 1867, Darwin wrote to Wallace about a problem he was having understanding how some caterpillars could have evolved conspicuous colour schemes. Darwin had come to believe that sexual selection, an agency to which Wallace did not attribute the same importance as Darwin did, explained many conspicuous animal colour schemes. However, Darwin realised that this could not apply to caterpillars. Wallace responded that he and Henry Bates had observed that many of the most spectacular butterflies had a peculiar odour and taste, and that he had been told by John Jenner Weir that birds would not eat a certain kind of common white moth because they found it unpalatable. "Now, as the white moth is as conspicuous at dusk as a coloured caterpillar in the daylight", Wallace wrote back to Darwin that it seemed likely that the conspicuous colour scheme served as a warning to predators and thus could have evolved through natural selection. Darwin was impressed by the idea. At a subsequent meeting of the Entomological Society, Wallace asked for any evidence anyone might have on the topic. In 1869, Weir published data from experiments and observations involving brightly coloured caterpillars that supported Wallace's idea. Warning colouration was one of a number of contributions Wallace made in the area of the evolution of animal colouration in general and the concept of protective colouration in particular.[93] It was also part of a lifelong disagreement Wallace had with Darwin over the importance of sexual selection. In his 1878 book Tropical Nature and Other Essays, he wrote extensively on the colouration of animals and plants and proposed alternative explanations for a number of cases Darwin had attributed to sexual selection.[94] He revisited the topic at length in his 1889 book Darwinism. In 1890, he wrote a critical review in Nature of his friend Edward Bagnall Poulton's The Colours of Animals which supported Darwin on sexual selection, attacking especially Poulton's claims on the "æsthetic preferences of the insect world".[95]

Wallace effect

In 1889, Wallace wrote the book Darwinism, which explained and defended natural selection. In it, he proposed the hypothesis that natural selection could drive the reproductive isolation of two varieties by encouraging the development of barriers against hybridisation. Thus it might contribute to the development of new species. He suggested the following scenario. When two populations of a species had diverged beyond a certain point, each adapted to particular conditions, hybrid offspring would be less well-adapted than either parent form and, at that point, natural selection will tend to eliminate the hybrids. Furthermore, under such conditions, natural selection would favour the development of barriers to hybridisation, as individuals that avoided hybrid matings would tend to have more fit offspring, and thus contribute to the reproductive isolation of the two incipient species.
This idea came to be known as the Wallace effect.[96] Wallace had suggested to Darwin that natural selection could play a role in preventing hybridisation in private correspondence as early as 1868, but had not worked it out to this level of detail.[97] It continues to be a topic of research in evolutionary biology today, with both computer simulation and empirical results supporting its validity.[98]

Application of theory to humans, and role of teleology in evolution

An illustration from the chapter on the application of natural selection to humans in Wallace's 1889 book Darwinism shows a chimpanzee.

In 1864, Wallace published a paper, "The Origin of Human Races and the Antiquity of Man Deduced from the Theory of 'Natural Selection'", applying the theory to humankind. Darwin had not yet publicly addressed the subject, although Thomas Huxley had in Evidence as to Man's Place in Nature. He explained the apparent stability of the human stock by pointing to the vast gap in cranial capacities between humans and the great apes. Unlike some other Darwinists, including Darwin himself, he did not "regard modern primitives as almost filling the gap between man and ape".[99] He saw the evolution of humans in two stages: achieving a bipedal posture freeing the hands to carry out the dictates of the brain, and the "recognition of the human brain as a totally new factor in the history of life. Wallace was apparently the first evolutionist to recognize clearly that ... with the emergence of that bodily specialization which constitutes the human brain, bodily specialization itself might be said to be outmoded."[99] For this paper he won Darwin's praise.

Shortly afterwards, Wallace became a spiritualist. At about the same time, he began to maintain that natural selection cannot account for mathematical, artistic, or musical genius, as well as metaphysical musings, and wit and humour. He eventually said that something in "the unseen universe of Spirit" had interceded at least three times in history. The first was the creation of life from inorganic matter.
The second was the introduction of consciousness in the higher animals. And the third was the generation of the higher mental faculties in humankind. He also believed that the raison d'être of the universe was the development of the human spirit.[100] These views greatly disturbed Darwin, who argued that spiritual appeals were not necessary and that sexual selection could easily explain apparently non-adaptive mental phenomena. While some historians have concluded that Wallace's belief that natural selection was insufficient to explain the development of consciousness and the human mind was directly caused by his adoption of spiritualism, other Wallace scholars have disagreed, and some maintain that Wallace never believed natural selection applied to those areas.[101][102] Reaction to Wallace's ideas on this topic among leading naturalists at the time varied. Charles Lyell endorsed Wallace's views on human evolution rather than Darwin's.[103][104] Wallace's belief that human consciousness could not be entirely a product of purely material causes was shared by a number of prominent intellectuals in the late 19th and early 20th centuries.[105] However, many, including Huxley, Hooker, and Darwin himself, were critical of Wallace.[106] As the historian of science Michael Shermer has stated, Wallace's views in this area were at odds with two major tenets of the emerging Darwinian philosophy, which were that evolution was not teleological (purpose driven) and that it was not anthropocentric (human-centred).[107] Much later in his life Wallace returned to these themes, that evolution suggested that the universe might have a purpose and that certain aspects of living organisms might not be explainable in terms of purely materialistic processes, in a 1909 magazine article entitled The World of Life, which he later expanded into a book of the same name;[108] a work that Shermer said anticipated some ideas about design in nature and directed evolution that would arise from various religious traditions throughout the 20th century.[105]

Assessment of Wallace's role in history of evolutionary theory

In many accounts of the development of evolutionary theory, Wallace is mentioned only in passing as simply being the stimulus to the publication of Darwin's own theory.[109] In reality, Wallace developed his own distinct evolutionary views which diverged from Darwin's, and was considered by many (especially Darwin) to be a leading thinker on evolution in his day, whose ideas could not be ignored. One historian of science has pointed out that, through both private correspondence and published works, Darwin and Wallace exchanged knowledge and stimulated each other's ideas and theories over an extended period.[110] Wallace is the most-cited naturalist in Darwin's Descent of Man, often in strong disagreement.[111] Wallace remained an ardent defender of natural selection for the rest of his life. By the 1880s, evolution was widely accepted in scientific circles, but Wallace and August Weismann were nearly alone among prominent biologists in believing that natural selection was the major driving force behind it.[112][113] In 1889, Wallace published the book Darwinism as a response to the scientific critics of natural selection.[114] Of all Wallace's books, it is the most cited by scholarly publications.[115]

Education

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Education Education is the transmissio...