by Andrew Brown
Sage was asked by Nature to comment on this unfolding story. He had had the opportunity, when Claus visited Britain, to examine some of the Orgueil material and was convinced by what he saw: ‘Anyone who had seen it under a microscope with varied depths of focus would be inclined to accept its organic character, yet so far no similar object has been found among protozoa, algae or even pollen grains.’48 Nor did Sage believe that the particles represented contamination from terrestrial sources, a significant counter-claim being made by many, because identical contamination was ‘highly improbable’ in meteorites that had fallen as far apart as France and Tanzania. It seemed possible that the carbonaceous material was either the product of extraterrestrial life processes or, if it had an inorganic origin, a possible source for the origin of life. It could no longer be assumed that life ‘must have originated on Earth, though it does not follow that it may not have’.49 Claus thought that although the ‘organisms’ from the meteorites were not similar to any terrestrial single-cell organisms, they did appear to have similar biochemistry because they reacted with Feulgen stain (as do nucleic acids); there was also evidence that different meteorites contained ‘substances extremely similar to amino acids and purines’.50 This raised the possibility that life forms, wherever they originated, followed similar biochemical pathways. In his view, the work of Claus and Nagy, while shattering many of his own assumptions, opened ‘the way to the solution of problems hitherto unthought of’.
When Klug vacated his attic office at 21 Torrington Square to move to Cambridge, he was replaced not by a molecular biologist, but by a young geochemistry researcher named John Kerridge. The transition reflected Bernal’s enthusiasm about the origin of life, which was a new subject for experimentation, whereas protein and virus research, while still absorbing, had passed beyond the pioneering stage. Kerridge was due to start work in January 1961, but found himself invited to the departmental Christmas party two weeks earlier. He arrived, a little shy as an outsider, and found the party going full blast. Sage quickly caught sight of him and waved him over. He said to Kerridge, ‘Meet a friend of mine, Linus Pauling’ and left the PhD student talking to the Nobel Laureate. Kerridge was hired to analyse carbonaceous meteorites in order to elucidate the mineralogy of their parent asteroids, and thereby provide clues about the conditions in which extra-terrestrial life might have emerged. As he started his researches, he was given the usual warning by others that he might hear more than one set of footsteps ascending to Bernal’s flat above his office during the evenings, at which point he should discreetly leave lest his innocence be ruined.
In 1963, Sage was invited to a select conference on the origins of life held in Wakulla Springs, under the auspices of Florida State University and NASA. He was unable to attend because of illness, but his paper was read in absentia.51 He reminded the audience that the problem confronting them was no longer confined to the origins of life on Earth, but needed to include ‘the origin of prelife states of complex carbon and nitrogen compounds’ that could have taken place inside the solar system or even beyond it. Although recent claims about carbon-based substances on meteorites being produced biologically were highly controversial, Bernal believed the study of meteorites was important if only because the geological history of the Earth was so turbulent, with its continental drifts and mountain building, that the me- teorites offered a unique opportunity to analyse primitive carbon compounds. But, he said, carbonaceous meteorites might not contain carbon molecules as such, rather an amorphous mass of carbon, nitrogen, hydrogen and oxygen like char. Bernal reported that Kerridge, at Birkbeck, had shown that the primary form of carbon in meteorites tended to be associated with low-temperature hydrated silicates (some similar to asbestos); the rounded particles or chondrules within carbonaceous meteorites contained water but with a higher deuterium content (heavy water) than found on Earth.
Whatever the mysteries about the initial synthesis of complex organic compounds, Sage thought that the next stage in biopoesis was ‘the most obscure and the most speculative’.52
Starting from an equilibrium mixture of carbon–nitrogen compounds, such as can be produced by the action of ionizing radiation acting on small molecules, how did it actually proceed to develop the features we now call those of life? Stage 2, as I see it, whatever the origin in space or the atmosphere of the equilibrium mixture, was played out here on Earth and in particular as part of the Earth’s hydrosphere, whether in free water or in mud banks.
The most interesting question, in his opinion, was: ‘How did the basic elements of molecular reproduction themselves originate?’ The ability of complex biochemical molecules to reproduce is essential to life. Present-day life depended on the reproduction of nucleic acids and the production of proteins – functions that take place within specific structural sites or organelles within the cell. The revolution in biology wrought by Watson and Crick had resulted in increased understanding of these mechanisms which, through their very perfection, made it ‘more difficult to see how they could have come into existence spontaneously together with their function’. Reproduction did not mean the occasional division of a complete organism into two or the emergence of a new bud.
It is evident that reproduction applies not so much to the whole organism as to every moment of its metabolism. The reproduction of nucleic acids and the production of protein molecules is essential to all vital processes as we meet them now. We can also say that they are essential to the actual structures of life, to organisms, and to the making of subcellular structures now revealed by the electron microscope and followed in detail by the studies of cytochemistry that also depend on this nucleic acid– protein cycle.53
One possible answer to the problem of how cell membranes and organelles arose, in Bernal’s opinion, was as a consequence of crystallization of identical small molecules. This would imply that the production of identical or nearly identical protein molecules preceded the appearance of internal cell architecture. He cited his own and Rosalind Franklin’s work on the structural subunits of TMV as an example of how such construction might take place. There was an important distinction between the possible modes of biopoesis (which depend on logic and chemistry) and the actual genesis of life (which must take account of the fossil record and the present biochemistry of life). Perhaps as an aside to Pirie, who was at the conference in Florida, Sage observed that:
Many people have argued and some still do, that the whole of life is a highly improbable process. In fact, it would not be difficult to prove that life could not exist; it would be far easier than to demonstrate that it must exist. But, as we have life and, indeed, are life, we have to accept it and, therefore, explain it.54
The philosophy of employing probability at all was critically examined by Peter Mora, a biochemist from the National Institutes of Health, in a paper titled ‘The folly of probability’. In his contribution, Mora also questioned the adequacy of the scientific method, especially the reductionism of physics, to comprehend something as inherently complex as life. Bernal read this paper, which he found to be salutary, but he could not bring himself to agree with Mora’s negative conclusions. Bernal, in his written comments, agreed with Mora that the present laws of physics ‘are insufficient to describe the origin of life’. To Mora, Sage continued,
this opens the way to teleology, even, by implication, to creation by an intelligent agent. Now both of these hypotheses were eminently reasonable before the fifteenth or possibly even before the nineteenth century. Nowadays they carry a higher degree of improbability than any of the hypotheses questioned by Dr Mora. If he thinks that he has shown conclusively that life cannot have originated by chance, only two alternatives remain. The first is that it did not arise at all, and that all we are studying is an illusion. This is the old argument of Parmenides, whose logic led him to believe that the Universe is One and that any apparent multiplicity is illusory. The other alternative is that life is a reality but that we are not yet clever enough to unravel the nature of its origin
which seems to me admittedly a priori more probable.55
Bernal’s essential point was that the debate on the origin of life had moved on from the metaphysical stage to one where the phenomenon of life was being analysed in terms of its underlying biochemistry. Pirie, who chaired that session of the conference, congratulated Mora for setting people thinking, but was ‘surprised at the improbably large number of occasions on which my reaction was almost the precise opposite to yours’!
Bernal published The Origin of Life in 1967 as a book for ‘the normal, intelligent reader’ giving a summary of current ideas as well as incorporating the historic essays of Oparin and Haldane as appendices.56 Since the study of the origin of life raised more questions than it answered, he revived a very old kind of practice – the inclusion of unanswered queries. He had done the same thing for his paper to the Florida conference in 1963, where he had listed 32 questions for the audience to think about. In the book, Sage attempted to answer his own questions. He stuck to the view that the elementary organic substances, whether formed on Earth or arriving by meteorite, became converted into the more complex molecules of life in the surface water of the Earth, probably adsorbed onto clay or some other mineral. In answer to the key question ‘How did the basic elements of molecular reproduction themselves originate?’ Sage offered the following answer.
The bases and amino acids were formed presumably abiotically and then selected. Some of the base and sugar phosphates have acted as protocoenzymes and were subsequently polymerized into nucleic acids. An intermediate stage in which short lengths of nucleic acids were attached to particular amino acids probably intervened, leading to the formation of transfer RNA, and hence to the whole process of replication.57
At the Moscow conference, a decade earlier, Bernal had first suggested the primacy of RNA over DNA in biopoesis.58 His reason for believing so was that DNA-containing structures always seem to be contained within a membranous envelope such as the cell nucleus, whereas RNA is found in the general milieu of the cell and may be a more versatile molecule. The notion of RNA as the key molecule for replication and also as an agent to catalyse the synthesis of proteins was an idea whose time had come in the late 1960s. It was written about by Carl Woese in his 1967 book, The Genetic Code, and suggested independently by Crick in Cambridge and Leslie Orgel at the Salk Institute for Biological Studies in San Diego. Subsequently, there has been the discovery of ribozymes, enzymes made of RNA, and the RNA world remains a popular view of how DNA–RNA–protein life got started.59 Bernal’s name should perhaps be added to the list of the originators of this theory.
Sage regarded the idea first put forward in his 1947 Guthrie lecture that the polymerization of small organic molecules floating in the primitive soup into more complex biochemical substances was facilitated by adsorption onto fine clay particles as his most original contribution. In the late 1970s, it was shown that amino acids coated onto clay surfaces can link up into short chains that resemble modern biological proteins.60 And just as he had suggested in the same lecture that quartz might impart handedness to any macromolecules assembled on its asymmetrical facets, experiments at the Carnegie Institution in 2000 showed that calcite (limestone) attracts left-handed and right-handed amino acid molecules differentially to its mirror-image crystal faces.61 Dorothy Hodgkin told a story about two of Sage’s friends marvelling at his versatility. One asked, ‘How is he, what is he doing now?’ ‘I don’t know’ the second replied, ‘The world is his oyster.’ ‘Rather’ said the first ‘is the universe his oyster – the world is his pearl.’62 More than half a century after he proposed the clay hypothesis, a paper was published that extended his idea to outer space – after analysing several meteorites (including the Orgueil), the authors (who even referred to Bernal’s The Physical Basis of Life) concluded that ‘the meteoritic organic matter is strongly associated with clay minerals. This association suggests that clay minerals may have had an important trapping and possibly catalytic role in chemical evolution in the early solar system prior to the origin of life on the early Earth.’63
19
Marxist Envoy
Soon after the war, Sage wrote that ‘the day of the wandering scholar is over’.1 He then spent much of the next twenty years attempting to revive the tradition. In addition to the triennial International Union of Crystallography meetings, invitations to speak at foreign universities, and his globe-trotting for the World Peace Council and the World Federation of Scientific Workers, he took several lengthy trips to nations that interested him. These visits were usually at the invitation of the national science academy of the country in question, and the ostensible reason for the visit would be a one-man review of their leading centres of science and technology. For emerging countries with limited resources, Sage represented expertise in physics, chemistry, crystallography, materials science and metallurgy, the building industry and agriculture. He was indefatigable and cheap. As a scientist, he regarded himself as a world citizen and was determined to do all he could to bring the benefits of pure and applied science to developing lands. If the places were not established communist states like China and the USSR, they were often ex-colonial nations that appeared ripe for conversion to some form of socialism, when, of course, the planning of science would become a central edict. For Sage, the visits offered an unrivalled opportunity to make friends and learn more about the culture of foreign parts – there would be excursions to historic sites and museums, where more than one head curator was gently corrected about their exhibits.
His first post-war visit to the USSR was in the summer of 1949, beginning with the Soviet Peace Congress in the Hall of Columns. After the Congress was over, he spent several days touring construction sites in Moscow, talking to architects and civil engineers. Tens of thousands of Muscovites were living in barracks, and Nikita Khrushchev, the Moscow party chief, was in charge of an emergency programme to build apartment blocks that succeeded, in no small measure, because of the bold decision to use prefabricated reinforced concrete.2 Bernal was impressed with the speed at which the buildings were erected and wrote several articles praising the construction techniques on his return to London. He spent the first week of September visiting scientific institutions in Moscow and giving lectures; for the second week he repeated this effort in Leningrad. He wrote to Sergei Vavilov, President of the Soviet Academy of Sciences, saying he had noticed ‘an enormous improvement in material means for science since his last visit in 1934’. He hoped for better communication with Soviet scientists and looked forward to exchange visits. He had canvassed support for the WFSW at the various institutes he visited. He closed his letter with ‘best wishes for a glorious future for Soviet science in the common service of mankind’.3 It was on this trip that he met Lysenko and took such a rosy view of his qualities.
After a term spent teaching and supervising research at Birkbeck, Sage was invited by the Indian Academy of Science to speak at its annual meeting in Bombay at the end of December.4 He was met at Bombay airport by Professor Sir C.V. Raman, founder and president of the Indian Academy, and director of the new Raman Institute of Research in Bangalore. After dropping his small suitcase at the Taj Hotel, Sage was taken straight to the new Institute of Nuclear Research, housed in what used to be the Royal Yacht Club, where he learned about their research on cosmic rays. Raman drove him up to the Malabar Hill, where he stood in the hanging gardens and watched the sun set over the city. Raman told Sage about his early life, growing up in an academic family in southern India; Sage was amused that he had decided to shorten his name to Raman from Venkataraman so that any scientific contribution he made might be more easily remembered. This certainly paid off when he discovered the Raman effect of scattered light in 1928.
Dinner that evening was at the home of some wealthy Parsees, who had invited other leading figures from the meeting as well as local dignitaries. Among the guests were the Joliot-Curies, and Sage spent time comparing notes on the USSR with Frédéric, who had been there three months earlier.
Sage also talked to the editor of a progressive Bombay newspaper, from whom he formed the impression that the Congress government had little control over business activity in the city, but were using the police to suppress communism.
The chief minister of Maharashtra state opened the Academy meeting with a speech in which he referred several times to Bernal’s book The Social Function of Science. This led to its author being subjected to ‘a mass attack of autograph hunters’ and multiple invitations to speak at Indian colleges. After the morning session, Bernal found himself at the Governor General’s house for lunch along with Sir Robert Robinson, the Oxford chemistry professor and President of the Royal Society, who was also an invited speaker at the Academy meeting. Protocol would not permit Sage to leave before the Governor General and so he had no chance to prepare his lecture. Indeed he only just managed to arrive back at the meeting in time to deliver his talk on ‘X-ray analysis and organic chemistry’ at 5pm. Following Bernal’s lecture, there were some good presentations by Indian scientists on textiles (but Bernal was disappointed that these contained no X-ray work).
Bernal talked to many of the Indian scientists at the meeting, and this was probably the occasion when he met G.N. Ramachandran, who had just completed a PhD under Peter Wooster’s supervision at Cambridge. Ramachandran, the recently appointed Professor of Physics at Madras University, always credited Bernal with steering him towards the structure of collagen as a worthwhile research topic. In Madras, the Central Leather Research Institute was virtually next door to Ramachandran’s laboratory, and in 1954 he was the first to describe collagen’s triple helix formation.5
On the drive from the Governor General’s house to the site of the meeting, Sage was depressed by the condition of Indian housing that he passed – ‘miserable lean-tos and shacks made mostly out of old rags and bits of wood, worse than anything I have seen in West Africa’.6 The peasants, he learned, paid rent to black market landlords. He cornered the chief minister that evening at a reception in ‘the most exquisite grounds of an extremely wealthy Parsee businessman’ to suggest how their situation might be alleviated by modern building techniques, but found that the premier ‘took a most defeatist attitude’.
