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Home > Category Index for Science Quotations > Category Index P > Category: Protein

Protein Quotes (44 quotes)

A DNA sequence for the genome of bacteriophage ΦX174 of approximately 5,375 nucleotides has been determined using the rapid and simple “plus and minus” method. The sequence identifies many of the features responsible for the production of the proteins of the nine known genes of the organism, including initiation and termination sites for the proteins and RNAs. Two pairs of genes are coded by the same region of DNA using different reading frames.
[Paper co-author]
Frederick Sanger, et al., 'Nucleotide Sequence of Bacteriophage ΦX174 DNA', Nature (1977), 265, 687.
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A final proof of our ideas can only be obtained by detailed studies on the alterations produced in the amino acid sequence of a protein by mutations of the type discussed here.
In Nobel Lecture (11 Dec 1962). Collected in Nobel Lectures, Physiology or Medicine 1942-1962 (1964).
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Advocacy of leaf protein as a human food is based on the undisputed fact that forage crops (such as lucerne) give a greater yield of protein than other types of crops. Even with connventional food crops there is more protein in the leafy parts than in the seeds or tubs that are usually harvested.
Quoted in 'India Children to Eat Leaf Protein in a Diet Test', New York Times (16 Dec 1973), 46.

Bottom trawling is a ghastly process that brings untold damage to sea beds that support ocean life. It’s akin to using a bulldozer to catch a butterfly, destroying a whole ecosystem for the sake of a few pounds of protein. We wouldn’t do this on land, so why do it in the oceans?
In 'Can We Stop Killing Our Oceans Now, Please?', Huffington Post (14 Aug 2013).
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But, further, no animal can live upon a mixture of pure protein, fat and carbohydrate, and even when the necessary inorganic material is carefully supplied, the animal still cannot flourish. The animal body is adjusted to live either upon plant tissues or the tissues of other animals, and these contain countless substances other than the proteins, carbohydrates and fats... In diseases such as rickets, and particularly in scurvy, we have had for long years knowledge of a dietetic factor; but though we know how to benefit these conditions empirically, the real errors in the diet are to this day quite obscure. They are, however, certainly of the kind which comprises these minimal qualitative factors that I am considering.
'The Analyst and the Medical Man', The Analyst (1906), 31, 395-6.
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Conclusion: Big helix in several chains, phosphates on outside, phosphate-phosphate inter-helical bonds disrupted by water. Phosphate links available to proteins.
Underlined in typewritten lecture notes, with handwritten annotations, as report (7 Feb 1952) on 'Colloquium November 1951'. As given in Anne Sayre, Rosalind Franklin and DNA (1975), 128.
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DNA that used to have some function way back in evolution but currently does not (and might possibly be revived if, say, an ancient parasite reappeared), DNA that controls how genes switch their protein manufacturing on and off, DNA that controls those, and so on. Some may actually be genuine junk. And some (so the joke goes) may encode a message like ‘It was me, I’m God, I existed all along, ha ha.
In Terry Pratchett, Ian Stewart and Jack Cohen, The Science of Discworld (2014), 218.
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Finally one should add that in spite of the great complexity of protein synthesis and in spite of the considerable technical difficulties in synthesizing polynucleotides with defined sequences it is not unreasonable to hope that all these points will be clarified in the near future, and that the genetic code will be completely established on a sound experimental basis within a few years.
From Nobel Lecture (11 Dec 1962), 'On the Genetic Code'. Collected in Nobel Lectures: Physiology or Medicine 1942-1962 (1964), 808.
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First they said my [cyclol] structure [of proteins] couldn’t exist. Then when it was found in Nature they said it couldn’t be synthesized in a laboratory. Then when it was synthesized they said it wasn’t important in any way.
Quoted in Maureen M. Julian in G. Kass­Simon and Patricia Farnes (eds.), Women of Science (1990), 368.
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Fish does not now—nor can it ever—feed the world. … Many developed, wealthy nations … dine on seafood more for taste than for necessity. … not one would on average incur any protein deficiency even if fish were completely removed from its dinner tables.
In Jacques Cousteau and Susan Schiefelbein, The Human, the Orchid, and the Octopus: Exploring and Conserving Our Natural World (2007), 153.
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Forests and trees make significant direct contributions to the nutrition of poor households ... [as] rural communities in Central Africa obtained a critical portion of protein and fat in their diets through hunting wildlife from in and around forests. The five to six million tonnes of bushmeat eaten yearly in the Congo Basin is roughly equal to the total amount of beef produced annually in Brazil – without the accompanying need to clear huge swathes of forest for cattle.
In 'Forests and food security: What we know and need to know', Forest News online blog by the Center for International Forestry Research (20 Apr 2011).
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From the intensity of the spots near the centre, we can infer that the protein molecules are relatively dense globular bodies, perhaps joined together by valency bridges, but in any event separated by relatively large spaces which contain water. From the intensity of the more distant spots, it can be inferred that the arrangement of atoms inside the protein molecule is also of a perfectly definite kind, although without the periodicities characterising the fibrous proteins. The observations are compatible with oblate spheroidal molecules of diameters about 25 A. and 35 A., arranged in hexagonal screw-axis. ... At this stage, such ideas are merely speculative, but now that a crystalline protein has been made to give X-ray photographs, it is clear that we have the means of checking them and, by examining the structure of all crystalline proteins, arriving at a far more detailed conclusion about protein structure than previous physical or chemical methods have been able to give.
'X-Ray Photographs of Crystalline Pepsin', Nature (1934), 133, 795.
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I should like to compare this rearrangement which the proteins undergo in the animal or vegetable organism to the making up of a railroad train. In their passage through the body parts of the whole may be left behind, and here and there new parts added on. In order to understand fully the change we must remember that the proteins are composed of Bausteine united in very different ways. Some of them contain Bausteine of many kinds. The multiplicity of the proteins is determined by many causes, first through the differences in the nature of the constituent Bausteine; and secondly, through differences in the arrangement of them. The number of Bausteine which may take part in the formation of the proteins is about as large as the number of letters in the alphabet. When we consider that through the combination of letters an infinitely large number of thoughts may be expressed, we can understand how vast a number of the properties of the organism may be recorded in the small space which is occupied by the protein molecules. It enables us to understand how it is possible for the proteins of the sex-cells to contain, to a certain extent, a complete description of the species and even of the individual. We may also comprehend how great and important the task is to determine the structure of the proteins, and why the biochemist has devoted himself with so much industry to their analysis.
'The Chemical Composition of the Cell', The Harvey Lectures (1911), 7, 45.
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In describing a protein it is now common to distinguish the primary, secondary and tertiary structures. The primary structure is simply the order, or sequence, of the amino-acid residues along the polypeptide chains. This was first determined by Sanger using chemical techniques for the protein insulin, and has since been elucidated for a number of peptides and, in part, for one or two other small proteins. The secondary structure is the type of folding, coiling or puckering adopted by the polypeptide chain: the a-helix structure and the pleated sheet are examples. Secondary structure has been assigned in broad outline to a number of librous proteins such as silk, keratin and collagen; but we are ignorant of the nature of the secondary structure of any globular protein. True, there is suggestive evidence, though as yet no proof, that a-helices occur in globular proteins, to an extent which is difficult to gauge quantitatively in any particular case. The tertiary structure is the way in which the folded or coiled polypeptide chains are disposed to form the protein molecule as a three-dimensional object, in space. The chemical and physical properties of a protein cannot be fully interpreted until all three levels of structure are understood, for these properties depend on the spatial relationships between the amino-acids, and these in turn depend on the tertiary and secondary structures as much as on the primary. Only X-ray diffraction methods seem capable, even in principle, of unravelling the tertiary and secondary structures.
Co-author with G. Bodo, H. M. Dintzis, R. G. Parrish, H. Wyckoff, and D. C. Phillips
'A Three-Dimensional Model of the Myoglobin Molecule Obtained by X-ray Analysis', Nature (1958) 181, 662.
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It has been recognized that hydrogen bonds restrain protein molecules to their native configurations, and I believe that as the methods of structural chemistry are further applied to physiological problems it will be found that the significance of the hydrogen bond for physiology is greater than that of any other single structural feature.
Nature of the Chemical Bond and the Structure of Molecules and Crystals (1939), 265.
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It is often said that all the conditions for the first production of a living being are now present, which could ever have been present. But if (and oh what a big if) we could conceive in some warm little pond with all sort of ammonia and phosphoric salts—light, heat, electricity present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present such matter would be instantly devoured, or absorbed, which would not have been the case before living creatures were formed.
Letter (1 Feb 1871) to Joseph Dalton Hooker. In The Life and Letters of Charles Darwin (1888), Vol. 3, 18.
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It is, I believe, justifiable to make the generalization that anything an organic chemist can synthesize can be made without him. All he does is increase the probability that given reactions will “go”. So it is quite reasonable to assume that given sufficient time and proper conditions, nucleotides, amino acids, proteins, and nucleic acids will arise by reactions that, though less probable, are as inevitable as those by which the organic chemist fulfills his predictions. So why not self-duplicating virus-like systems capable of further evolution?
The Place of Genetics in Modern Biology (1959),18.
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Knowing what we know from X-ray and related studies of the fibrous proteins, how they are built from long polypeptide chains with linear patterns drawn to a grand scale, how these chains can contract and take up different configurations by intramolecular folding, how the chain- groups are penetrated by, and their sidechains react with, smaller co-operating molecules, and finally how they can combine so readily with nucleic acid molecules and still maintain the fibrous configuration, it is but natural to assume, as a first working hypothesis at least, that they form the long scroll on which is written the pattern of life. No other molecules satisfy so many requirements.
William Thomas Astbury and Florence O. Bell. 'Some Recent Developments in the X-Ray Study of Proteins and Related Structures', Cold Spring Harbor Symposia on Quantitative Biology, 1938, 6, 1144.
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Life goes faster on protein.
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Life is the mode of action of proteins.
Engels’ definition of life, according to William Bragg, as given in Andrew Brown, J.D. Bernal: The Sage of Science (2005), 343.
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Man's health and well-being depends upon, among many things, the proper functioning of the myriad proteins that participate in the intricate synergisms of living systems.
Nobel Prize Banquet Speech (10 Dec 1972).
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My own thinking (and that of many of my colleagues) is based on two general principles, which I shall call the Sequence Hypothesis and the Central Dogma. The direct evidence for both of them is negligible, but I have found them to be of great help in getting to grips with these very complex problems. I present them here in the hope that others can make similar use of them. Their speculative nature is emphasized by their names. It is an instructive exercise to attempt to build a useful theory without using them. One generally ends in the wilderness.
The Sequence Hypothesis
This has already been referred to a number of times. In its simplest form it assumes that the specificity of a piece of nucleic acid is expressed solely by the sequence of its bases, and that this sequence is a (simple) code for the amino acid sequence of a particular protein...
The Central Dogma
This states that once 'information' has passed into protein it cannot get out again. In more detail, the transfer of information from nucleic acid to nucleic acid, or from nucleic acid to protein may be possible, but transfer from protein to protein, or from protein to nucleic acid is impossible. Information means here the precise determination of sequence, either of bases in the nucleic acid or of amino acid residues in the protein. This is by no means universally held—Sir Macfarlane Burnet, for example, does not subscribe to it—but many workers now think along these lines. As far as I know it has not been explicitly stated before.
'On Protein Synthesis', Symposia of the Society for Experimental Biology: The Biological Replication of Macromolecules, 1958, 12, 152-3.
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On the whole, at least in the author's experience, the preparation of species-specific antiserum fractions and the differentiation of closely related species with precipitin sera for serum proteins does not succeed so regularly as with agglutinins and lysins for blood cells. This may be due to the fact that in the evolutional scale the proteins undergo continuous variations whereas cell antigens are subject to sudden changes not linked by intermediary stages.
The Specificity of Serological Reactions (1936), 12-3.
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One amino acid does not a protein make—let alone a being.
From Oasis in Space (1988). Quoted in Peter Douglas Ward and Donald Brownlee, Rare Earth (2000), 55.
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Orgel's First Rule: Whenever a spontaneous process is too slow or too inefficient a protein will evolve to speed it up or make it more efficient.
In Jack D. Dunitz and Gerald F. Joyce, 'Leslie Eleazer Orgel', Biographical Memoirs of Fellows of the Royal Society (2013), Vol. 59, 286.
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Our conception of a native protein molecule (showing specific properties) is the following. The molecule consists of one polypeptide chain which continues without interruption throughout the molecule (or, in certain cases, of two or more such chains); this chain is folded into a uniquely defined configuration, in which it is held by hydrogen bonds between the peptide nitrogen and oxygen atoms and also between the free amino and carboxyl groups of the diamino and dicarboxyl amino acid residues.
The characteristic specific properties of native proteins we attribute to their uniquely defined configurations.
The denatured protein molecule we consider to be characterized by the absence of a uniquely defined configuration.
[Co-author with American chemist, Linus Pauling (1901-94)]
'On the Structure of Native, Denatured, and Coagulated Proteins', Proceedings of the National Academy of Sciences of the United States of America (1936), 22, 442-3.
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Protein synthesis is a central problem for the whole of biology, and that it is in all probability closely related to gene action.
'On Protein Synthesis', Symposia of the Society for Experimental Biology: The Biological Replication of Macromolecules, 1958, 12, 160.
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Since many cases are known in which the specificities of antigens and enzymes appear to bear a direct relation to gene specificities, it seems reasonable to suppose that the gene’s primary and possibly sole function is in directing the final configurations of protein molecules.
Assuming that each specific protein of the organism has its unique configuration copied from that of a gene, it follows that every enzyme whose specificity depends on a protein should be subject to modification or inactivation through gene mutation. This would, of course, mean that the reaction normally catalyzed by the enzyme in question would either have its rate or products modified or be blocked entirely.
Such a view does not mean that genes directly “make” proteins. Regardless of precisely how proteins are synthesized, and from what component parts, these parts must themselves be synthesized by reactions which are enzymatically catalyzed and which in turn depend on the functioning of many genes. Thus in the synthesis of a single protein molecule, probably at least several hundred different genes contribute. But the final molecule corresponds to only one of them and this is the gene we visualize as being in primary control.
In 'Genetics and Metabolism in Neurospora', Physiological Reviews, 1945, 25, 660.
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So many of the chemical reactions occurring in living systems have been shown to be catalytic processes occurring isothermally on the surface of specific proteins, referred to as enzymes, that it seems fairly safe to assume that all are of this nature and that the proteins are the necessary basis for carrying out the processes that we call life.
In 'The Physical Basis of Life', (1951), 39. As given in Andrew Brown, J.D. Bernal: The Sage of Science (2005), 359.
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Sometimes progress is slow. But then there does come a time when a lot of people accept a new idea and see ways in which it can be exploited. And because of the larger number of workers in the field, progress becomes rapid. That is what happened with the study of protein structure.
From interview with Neil A. Campbell, in 'Crossing the Boundaries of Science', BioScience (Dec 1986), 36, No. 11, 739.
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The century of biology upon which we are now well embarked is no matter of trivialities. It is a movement of really heroic dimensions, one of the great episodes in man’s intellectual history. The scientists who are carrying the movement forward talk in terms of nucleo-proteins, of ultracentrifuges, of biochemical genetics, of electrophoresis, of the electron microscope, of molecular morphology, of radioactive isotopes. But do not be misled by these horrendous terms, and above all do not be fooled into thinking this is mere gadgetry. This is the dependable way to seek a solution of the cancer and polio problems, the problems of rheumatism and of the heart. This is the knowledge on which we must base our solution of the population and food problems. This is the understanding of life.
Letter to H. M. H. Carsan (17 Jun 1949). Quoted in Raymond B. Fosdick, The Story of the Rockefeller Foundation (1952), 166.
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The initiation of the fermentation process does not require so complicated an apparatus as is represented by the living cell. The agent responsible for the fermenting action of the press juice is rather to be regarded as a dissolved substance, doubtless a protein; this will be denoted zymase.
'Gahrung ohne Hefezellen', Berichte der deutschen chemischen Gesellschaft, 1897, 30, 119-20. Trans. in Joseph S. Froton, Proteins, Enzymes, Genes: The Interplay of Chemistry and Biology (1999), 117.
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The language of the genes has a simple alphabet, not with twenty-six letters, but just four. These are the four different DNA bases—adenine, guanine, cytosine and thymine (A, G, C and T for short). The bases are arranged in words of three letters such as CGA or TGG. Most of the words code for different amino acids, which themselves are joined together to make proteins, the building blocks of the body.
The Language of the Genes: Biology, History and the Evolutionary Future (1993), 3.
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The oceans are the life support system of this planet, providing us with up to 70 percent of our oxygen, as well as a primary source of protein for billions of people, not to mention the regulation of our climate.
In 'Why Exploring the Ocean is Mankind’s Next Giant Leap', contributed to CNN 'Lightyears Blog' (13 Mar 2012).
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The serum, when subjected to heat, coagulates and hardens like egg. This property is one of its striking characteristics; it is attributed to a particular substance which is thereby readily recognizable, and which is called albumine, because it is the one present in egg white, termed albumen.
Systčme des Connaissances Chimiques (1801), Vol. 5, 117. Trans. Joseph S. Fmton, Proteins, Enzymes, Genes: The Interplay of Chemistry and Biology (1999), 161.
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The varieties of chemical substances actually found in living things are vastly more restricted than the possible varieties. A striking illustration is that if one molecule each of all the possible types of proteins were made, they would together weigh more than the observable universe. Obviously there are a fantastically large number of protein types that are not made by living cells.
In The Closing Circle: Nature, Man, and Technology (2014).
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There is a finite number of species of plants and animals—even of insects—upon the earth. … Moreover, the universality of the genetic code, the common character of proteins in different species, the generality of cellular structure and cellular reproduction, the basic similarity of energy metabolism in all species and of photosynthesis in green plants and bacteria, and the universal evolution of living forms through mutation and natural selection all lead inescapably to a conclusion that, although diversity may be great, the laws of life, based on similarities, are finite in number and comprehensible to us in the main even now.
Presidential Address (28 Dec 1970) to the American Association for the Advancement of Science. 'Science: Endless Horizons or Golden Age?', Science (8 Jan 1971), 171, No. 3866, 24.
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There is no existing ‘standard of protein intake’ that is based on the sure ground of experimental evidence. ... Between the two extremes of a very high and a very low protein intake it is difficult to prove that one level of intake is preferable to another. ... Physiologists, in drawing up dietary standards, are largely influenced by the dietary habits of their time and country.
Nutrition and Public Health', League of Nations Health Organization Quarterly Bulletin (1935) 4, 323–474. In Kenneth J. Carpenter, 'The Work of Wallace Aykroyd: International Nutritionist and Author', The Journal of Nutrition (2007), 137, 873-878.
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Trying to determine the structure of a protein by UV spectroscopy was like trying to determine the structure of a piano by listening to the sound it made while being dropped down a flight of stairs.
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We are fishing out the top of the food chain, and it’s pretty crucial because about 200 million people depend on fish and fishing for their livelihood, and about a billion people, mostly in poorer countries, depend on fish for their protein. So this is a big problem. Good news is, it’s fixable.
From transcript of PBS TV interview by Tavis Smiley (28 Mar 2011).
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We should first look at the evidence that DNA itself is not the direct template that orders amino acid sequences. Instead, the genetic information of DNA is transferred to another class of molecules which then serve as the protein templates. These intermediate templates are molecules of ribonucleic acid (RNA), large polymeric molecules chemically very similar to DNA. Their relation to DNA and protein is usually summarized by the central dogma, a How scheme for genetic information first proposed some twenty years ago.
In Molecular Biology of the Gene (1965), 281-282.
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We should like to propose instead that the specificity of DNA self replication is accomplished without recourse to specific protein synthesis and that each of our complementary DNA chains serves as a template or mould for the formation onto itself of a new companion chain.
[Co-author with Francis Crick]
In James D. Watson and Francis H. C. Crick, 'The Structure of DNA', Cold Spring Harbor Symposium on Quantitative Biology (1953), 18, 128.
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What intellectual phenomenon can be older, or more oft repeated, than the story of a large research program that impaled itself upon a false central assumption accepted by all practitioners? Do we regard all people who worked within such traditions as dishonorable fools? What of the scientists who assumed that the continents were stable, that the hereditary material was protein, or that all other galaxies lay within the Milky Way? These false and abandoned efforts were pursued with passion by brilliant and honorable scientists. How many current efforts, now commanding millions of research dollars and the full attention of many of our best scientists, will later be exposed as full failures based on false premises?
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When ultra-violet light acts on a mixture of water, carbon dioxide, and ammonia, a vast variety of organic substances are made, including sugars and apparently some of the materials from which proteins are built up…. But before the origin of life they must have accumulated till the primitive oceans reached the consistency of hot dilute soup…. The first living or half-living things were probably large molecules synthesized under the influence of the sun’s radiation, and only capable of reproduction in the particularly favorable medium in which they originated….
In 'The Origin of Life', The Inequality of Man: And Other Essays (1932, 1937), 152.
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Carl Sagan Thumbnail In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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