by Peter Watson
Haile Selassie was overthrown in September 1974 in a coup which resulted in a Marxist military dictatorship in Ethiopia. This made work difficult, but Johanson managed to return and in 1975 made a yet further extraordinary discovery: a ‘first family’ of thirteen individuals – males, females, adults, juveniles, children, some two hundred fossils at one site, Site 333, as it became known. And in the following year, 1976, together with the French archaeologist Hélène Roche, he found simple basalt tools, dating back to 2.5 million years. This all meant a complete revision of humankind’s origins. Tool-making was much older than anyone imagined, as was upright walking. And it was clearly something indulged in first by Australopithecus, not the Homo genus.
Further finds in Hadar were prevented by another deterioration in the political situation in Ethiopia (another military coup in Addis Ababa). During this interregnum the southern end of the Rift Valley came back into the spotlight. In the mid-1970s Mary Leakey had been working in Laetoli, a site thirty miles from Olduvai, an area of sandstone gullies that cut into a plateau, very different from the gorge. She had been going there for many years and had recently found two jaws dating from 3.6 to 3.8 million years ago. In the last week of July 1976 she was joined by four other scientists, among them Andrew Hill and Kay Behrensmeyer. The newcomers, in high spirits, were all taken on a tour of the site on the morning after their arrival, and an elephant-dung fight broke out. Ducking into a flat gully to look for ammunition, Hill and Behrensmeyer came across a hard layer of volcanic ash – in which, as they suddenly noticed, there were elephant footprints. They dropped to their knees for a closer look, and then called the others. These were not fresh prints, but fossilised, and scattered near the elephant tracks were those of buffalos, giraffes, and birds. There were even a few ancient raindrops. What must have happened was that a spurt of volcanic ash, given off by a nearby mountain, had settled and then been rained upon, turning it into a form of cement. While this ‘cement’ was wet, animals walked across it, then another layer of ash was deposited on the top. Over the centuries, the top layer had weathered away to reveal the fossil footprints. It was an unusual find, but Mary Leakey told everyone to look out for hominid footprints – that would certainly make news. They searched all through August, but not until one day in September did they find some prints that looked hominid, with signs of a big toe. There were two sets, one much larger than the other, and they stretched for eighteen feet across the ancient ‘cement.’ In February 1978 Mary Leakey felt confident enough to announce the discovery. What was especially interesting was that the volcanic ash was dated to 3.7 million years ago, slightly earlier than the Ethiopian sites. From the pattern of indentations, some experts thought that whoever this hominid was, he did not walk upright all the time. So was this the period when man first began to walk upright?23
The answer did not come from Mary Leakey. The Laetoli bones and jaws had been given to Tim White, an American palaeontologist, whose job it was to describe them meticulously. However, White, a difficult man, fell out with both Richard and Mary Leakey. Worse, from the Leakey point of view, he subsequently teamed up with Don Johanson, and this pair proceeded to examine and analyse all the fossils from Laetoli and Hadar, all those aged between 3 and 4 million years old. They revealed their conclusions in 1979 in Science, claiming that what they had was a single species of hominid that was different to, and the ancestor of, many others.24 This species, which they named Australopithecus afarensis, they said was fully bipedal and showed marked sexual dimorphism (the males were much bigger than the females), though even the males were no more than four feet six. Their brains were in the chimpanzee range and their faces pronounced, like the apes; their teeth were halfway between those of the apes and humans. Most controversially, Johanson and White claimed that A. afarensis was the ancestor of both the Australopithecus and the Homo genus, ‘which therefore must have diverged some time after three million years ago.’25
At the beginning it had been Johanson and White’s intention to include Mary Leakey as a coauthor, but Mary was unhappy with the label Australopithecus being attached to the fossils she had discovered. The convention in science is for the discoverer to have the first ‘say’ in publishing the fossils that he or she finds, and to name them. After that, of course, other scientists are free to agree or disagree. By including Mary’s discoveries in their paper, Johanson and White were not only breaking with tradition; they knew by then that they were specifically going against her own interpretation. But they were anxious to claim for A. afarensis the tide of common ancestor of almost all known hominid fossils and so went ahead anyway. This caused a bitter feud that has never healed.26
Beyond the personal dimension, however, A. afarensis has provoked much rethinking.27 At the time it was given its name, the predominant view was that bipedalism and tool using were related: early man walked on two feet so as to free his hands for tools. But according to Johanson and White, early man was bipedal at least half a million years before tool using came in. The latest thinking puts bipedalism alongside a period of drying in Africa, when the forest retreated and open savannah grasslands spread. In such an environment, upright walking would have offered certain selective advantages – upright early man would have been faster, his body would have cooled more quickly, and he could have roamed over greater distances, with his hands free to carry food home, or back to his offspring. So although the bitterness was personally unpleasant, it did provoke useful new ideas about man’s origins.28
Since the discovery of the helical structure of DNA in 1953, the next theoretical advance had come in 1961, when Francis Crick and Sidney Brenner in Cambridge had shown that the amino acids that make up the proteins of life are actually coded by a triplet of base pairs on DNA strands. That is, of the four bases – (a)denine, (c)ytosine, (g)uanine, and (t)hymine – three, in certain arrangements, such as CGT or ATG, code for specific acids. But more practical advances involved two ways of manipulating DNA that proved integral to the process of what became known as genetic engineering. The first was cloning, the second, gene sequencing.
In November 1972 Stanley Cohen heard a lecture in Hawaii delivered by Herbert Boyer, a microbiologist from the University of California at San Francisco. Boyer’s lecture was about certain substances known as ‘restriction enzymes.’ These were substances which, when they came across a certain pattern of DNA bases, cut them in two. For example, every time they came across a T(hymine) followed by an A(denine), one restriction enzyme (of which there are several) would sever the DNA at that point. However, as Boyer told the meeting, restriction enzymes did more than this. When they cut, they did not form a blunt end, with both strands of the double helix stopping at the same point; instead they formed jagged or steplike ends, one part jutting out, slightly longer than the other. Because of this, the ends were what scientists labelled ‘sticky,’ in that the flaps attracted complementary bases.29 At the time he attended Boyer’s lecture, Cohen was himself working on plasmids, microscopic loops of DNA that lurk outside a bacterium’s chromosome and reproduce independently. As Cohen took in what Boyer was saying, he saw an immediate – and revolutionary – link to his own work. Because plasmids were loops, if they were cut with one of Boyer’s restriction enzymes, they would become like broken rings, the two broken ends being mirror images of each other. Therefore, strips of DNA from other animals, and it didn’t matter which (a lion, say, or an insect), if inserted into the bacterium with ‘split rings,’ would be taken up. The significance of Cohen’s idea lay in the fact that the plasmid replicated itself many times in each cell, and the bacterium divided every twenty minutes. With this form of replication and division, more than a million copies of the spliced DNA could be created within a day.30
After the lecture, Cohen sought out Boyer. As Walter Bodmer and Robin McKie tell the story, in their history of the genome project, the two microbiologists adjourned to a delicatessen near Waikiki Beach and, over corned beef sandwiches, agreed on a collaboration that bore its first fruits
in the Proceedings of the National Academy of Sciences in November 1973, when they announced the first report of successful cloning. From now on there was enough DNA to experiment with.31
The next step – important both practically and theoretically – was to explore the sequence of bases in the DNA molecule. Sequencing was necessary because if biologists were to discover which genes governed which aspects of functioning, the exact order needed to be understood. Fred Sanger in Cambridge, England, and Walter Gilbert in Cambridge, Massachusetts (Harvard), both discovered methods of doing this, and both received a Nobel Prize for their efforts. But Sanger’s method was identified first and is the more widely used.* Earlier, Sanger had developed a way of identifying the amino acids that make up proteins, and this had earned him his first Nobel, when he discovered the structure of insulin. But that method was far too slow to work with DNA, which is a very long molecule. Moreover, it is made up from only four subunits (A, C, G, and T), so long sequences would need to be understood before they could be related to properties. His breakthrough was the creative use of chemicals called dideoxy, otherwise known as chain terminators.’32 These are in fact imperfect forms of adenine, cytosine, guanine, and thymine; when mixed with DNA polymerase, the DNA-copying enzyme, they form sequences, but incompletely – in fact they stop, are terminated, at either A, C, G, or T.33 As a result they form DNA of varying lengths, each time stopping at the same base. Imagine, for the sake of argument, a strip of DNA that reads: CGTAGCATCGCTGAG. This, treated with adenine (A) terminators would produce strips in which growth stops at positions 4, 7, and 15, whereas the thymine (T) terminator would produce strips where growth stops at 3, 8, and 12, and so on. The technique actually to separate out these different strands consisted of placing the DNA in a tray of special gel, in which an electrical field had been applied to opposite ends. DNA, being negatively charged, is attracted to the positive pole, with the smaller fragments pulled faster than the larger ones, meaning that the strands eventually separate out, according to size. The DNA is then stained, and the sequence can be read. The technique was announced in Nature on 24 February 1977, and it was from that moment, coming on top of the cloning experiments, that genetic engineering may be said to have begun.34
Just over a year later, on 24 August 1978, Genentech, founded by Boyer and a young venture capitalist called Robert Swanson, announced that it had produced human insulin by this method – gene sequencing and cloning – and that it had concluded a deal with Eli Lilly, the pharmaceutical giant, for the mass manufacture of the substance. Two years later, in October 1980, when Genentech offered 1,100,000 of its shares for sale to the public, another phase in the microbiological revolution was born: offered at $35 a share, the stock immediately jumped to $89, and Boyer, who had invested just $500 in the company in early 1974, saw the value of his 925,000 shares leap to more than $80 million. No physicist was ever worth so much.35
Compared with the electron and other fundamental particles, the gene had taken some time to be isolated and broken down into its component parts. But as with physics, the experimental and theoretical work went in tandem.
Beginning in the 1970s a new form of literature began to appear. It grew out of Robert Ardrey’s works but was more ambitious. These were books of biology but with a distinct philosophical edge. However, they were not written by journalists, or dramatists, as Ardrey was, or Gordon Rattray Taylor was, in The Biological Time Bomb, or by scientific popularisers, as Desmond Morris was essentially in The Naked Ape, but by the leading scientists themselves. These books each contained a fair amount of complex biology, but they had wider ambitions too.
The first appeared in 1970 in French and a year later in English. Its author was Jacques Monod, part of a three-man team that had won the Nobel Prize in 1965 for uncovering the mechanism by which genetic material synthesises protein. In Chance and Necessity, Monod sought to use the latest biology, since Watson and Crick’s discovery of the double helix, to define life, and in considering what life itself is, went on to consider the implications that might have for ethics, politics, and philosophy. The book is almost certainly more impressive now, at the end of the century and with the benefit of hindsight, than when it was first published (it was republished by Penguin in 1997). This is because Monod’s thinking foreshadowed many of the ideas promulgated by biologists and philosophers who are now much better known than Monod, authors like E. O. Wilson, Stephen J. Gould, Richard Dawkins, and Daniel Dennett.
Although a biologist, Monod’s underlying insight was that life is essentially a physical and even mathematical phenomenon. His initial purpose was to show how entities in the universe can ‘transcend’ the laws of that universe while nevertheless obeying them. Or, as he put it, evolution does not confer ‘the obligation’ to exist but it does confer ‘the right’ to exist. For Monod, two of the great intellectual successes of the twentieth century, the free market and the transistor, share an important characteristic with life itself: amplification. The rules allow for the constituent parts to spontaneously – naturally – produce more of whatever system they are part of. On this reasoning there is nothing in principle unique about life.
In the technical part of his book, Monod showed how proteins and nucleic acids, the two components which all life is made from, spontaneously adopt certain three-dimensional forms, and that it is these three-dimensional forms which predetermine so much else. It is this spontaneous assembly that, for Monod, is the most important element of life. These substances, he says, are characterised by physical – and therefore mathematical – properties. ‘Great thinkers, Einstein among them, have often … wondered at the fact that mathematical entities created by man can so faithfully represent nature even though they owe nothing to experience.’ Again Monod implies that there is nothing especially ‘wonder’-ful about this – life is just as much about mathematics and physics as it is about biology. (This foreshadowed work we shall be considering in the last chapter.)
He went on to argue that evolution can only take place at all because of the ability of nucleic acids to reproduce themselves exactly, and this therefore means that only accident can produce mutations. In that sense, the universe was and is accidental (statistical and, therefore, again mathematical). This too, he felt, had profound implications. To begin with, evolution did not apply only to living things: adaptation is another expression of time, no less than another function of the second law of thermodynamics. Living things, as isolated, self-contained energetic systems, seem to operate against entropy, except that it is inconceivable for evolution – being a function of time – to go backwards. This implies that life, being an essentially physical phenomenon, is temporary: different life forms will battle against each other until a greater disorder takes over again.
No less controversially, but a good deal less apocalyptically, and anticipating the work of E. O. Wilson, Richard Dawkins, and others, Monod felt that ideas, culture, and language are survival devices, that there is survival value in myth (he avoided use of the term religion), but that they will in time be replaced. (He thought Christianity and Judaism more ‘primitive’ religions in this sense than, say, Hinduism, and implied that the latter would outlast Judaeo-Christianity.) And he felt that the scientific approach, as epitomised in the theory of evolution, which is a ‘blind’ process, not leading to any teleological conclusion, is the most ‘objective’ view of the world, in that it does not involve any one set of individuals having greater access to the truth than any other group. In this sense he thought that science disproves and replaces such ideas as animism, Bergson’s vitalism, and above all Marxism, which presents itself as a scientific theory of the history of society. Monod therefore saw science not simply as a way of approaching the world, but as an ethical stance, from which other institutions of society could only benefit.
Not that he was blind to the problems such an attitude brought with it. ‘Modern societies, woven together by science, living from its products, have become as dependent upon it as an addict on his drug
. They owe their material wherewithal to this fundamental ethic upon which knowledge is based, and their moral weakness to those value-systems, devastated by knowledge itself, to which they still try to refer. The contradiction is deadly. It is what is digging the pit we see opening under our feet. The ethic of knowledge that created the modern world is the only ethic compatible with it, the only one capable, once understood and accepted, of guiding its evolution.’36
Monod’s vision was broad, his tone tentative, as befitted someone new to philosophy, feeling his way and not trained in the discipline. His vision of ‘objective knowledge’ largely ignored the work of Thomas Kuhn and would come under sustained attack from philosophers in the years that followed. But not all the biologists who came after Monod were as humble. Two other books published in the mid-1970s were much more aggressive in making the link between genes, social organisation, and human nature.