In The Origin of Species, the Englishman Charles Darwin identifies natural selection as the means by which species have differentiated and then stabilised: in the struggle for life, only the ‘fittest’, the most adapted to their environment, have survived. Selection is made from unexpected variations, entirely governed by chance. Necessity intervenes only afterwards.
‘It took the genius of Darwin’, says Jacques Monod, ‘to impose the idea that teleonomy proceeds from emergence, which creates, sharpens, and amplifies it’ (Chance and Necessity).
The naturalist Lamarck, however, advances the opposite hypothesis. According to him, living beings are ceaselessly ‘readjusted’ by the environment. The characters acquired by individuals during their existence are automatically transmitted to their descendants. Weismann’s work shows that this is not the case. The environment does not have the means to ‘teach heredity’. It influences the external constitution, the soma, but not the hereditary stock, the germen, which each individual receives by inheritance and transmits in turn.
This distinction of soma and germen suggests that reproduction, even in man, is not the expression of a conscious will. It is not man who decides to perpetuate himself, but life which perpetuates itself through him. The differentiation of the sexes is the detour which it employs for this purpose. Family structures, society, and individual attractiveness play only on the modalities. ‘The germinal lineage forms the skeleton of the species upon which individuals form like excrescences. It is no longer the chicken that produces the egg. It is, in the words of Butler, the egg which has found in the hen a useful means for recreating an egg’.
At the same time, we realise that evolution has a meaning: the more evolved the species are, the more they move away from the undifferentiated world of amoebae and bacteria, the more they are specialised and individualised.
In the fourth stage, that of the gene, the scholarly world recognises that heredity is governed by interesting laws, not individuals, but populations. These laws are expressed in a rigorous fashion, under the form of significant statistical frequencies. ‘What matters’, explains Jacob, ‘is knowing not which particles collide at a given moment, but how many collisions there are on average, and what is the probability of a particle participating in it’.
One evening in February 1865, a monk from the town of Brünn (now Brno), Gregor Johann Mendel, read a paper on the hybridisation of pea plants in front of members of the local society of natural sciences. There were about forty people there. Mendel is patiently heard, politely applauded. Upon his death a few years later, his memory will be completely forgotten. Today it is regarded as the birth of modern genetics.
By hybridising his peas in the garden of his monastery, Mendel had succeeded in following the mode of transmission of the hereditary characteristics contained in the germen. This does not happen at random, but according to rigorous statistical laws that concern not the individuals, but the populations, as Darwin had foreseen. ‘With Mendel, biological phenomena suddenly acquire the rigor of mathematics’. (Gibbs and Boltzmann, at the same time, discovered the principle of calculating probabilities).
Finally, the gene structure shines for its part. In his laboratory, the biologist manages to decompose the living cells into inert physico-chemical constituents. Genes and chromosomes ‘registered’ [or ‘inscribed’] in germ cells deliver their secret, and let the molecule of the nucleic acid appear. The notion of ‘vital force’ disappears. It is replaced by that of energy. The notion of heredity is expanded. The genetic code is deciphered.
The Secret of the ‘Double Helix’
This code is a sequence of chemical patterns. ‘It is a message written, not with ideograms, as in Chinese’, notes François Jacob, ‘but with an alphabet, like Morse’. Just as a sentence constitutes a segment of text, so too does a gene corresponds to a segment of the nucleic acid. In both cases, an isolated symbol does not mean anything; only the combination of signs takes on meaning’.
‘Deoxyribonucleic acid (DNA), constituent of chromosomes, guardian of heredity, and source of evolution’, writes Monod, ‘is the philosophical stone of biology’!
In the space of twenty years, the structure of DNA, the famous ‘double helix’, has thus made a breakthrough. Biochemistry and then molecular biology made their appearance. ‘Molecular biology’, specifies Michel Foucault (Les mots et les choses),367 also a professor at the Collège de France, ‘locates in the transmission of the genetic code (the link between nucleic acids and the proteins) errors, omissions, mix-ups, and likens them to the blunders or unintended findings of a scribe in a moment of distraction. All throughout life, chance plays with the discontinuous’.
Turning to the question of the ‘nature of life’, Mr. Jacob writes: ‘The operational value of the concept of life has only been diluted and its power of abstraction has only declined. Life is no longer questioned today in laboratories. One no longer seeks to define its contours. We only attempt to analyse living systems’.
François Jacob understands that the question is, if not meaningless, at least beyond communicable scope. For those who work in a laboratory, to say what life is means to describe how it manifests itself. And to describe a living system is to study its history and its structure. The logic of organisation, the logic of evolution, these are the ‘algorithms’ of the living world.
The lessons that can now be drawn, however, are of direct concern to us. Societies themselves are organisms. ‘There does not appear’, writes André Lwoff in L’order biologique,368 ‘to be anything in common between a molecular society and a human society. And yet one cannot fail to be struck by a certain analogy between the phylogenetic evolution of organisms and the historical evolution of societies. Variation and selection have intervened in both cases. And then the interactions that govern the molecular and cellular order recall the phenomena that ensure the functioning of human societies: molecules and men are also subjected to harsh constraints. Finally, molecules in revolt and parasitic molecules also have their equivalents in human societies’.
New structures remain to be discovered. ‘Today’, writes François Jacob, ‘the world is messages, codes, information. What dissection, tomorrow, will dislocate our objects in order to recompose them into a new space? What Russian doll will emerge?
‘The dice govern us’, said Michel Foucault.
*
La logique du vivant, a study by François Jacob.369 Gallimard, 354 pages.
Evolution
‘When the masses hate the elites, they are as stupid as the woodcutter who saws the branch that he sits on. In striking them, they strike themselves, for everything that is contrary to the elite is at the same time detrimental to the entire collective. Egalitarianism is opposed to social and intellectual progress; it abolishes the motivation of the individual, desirous of acquiring more or better, suppresses the spirit of initiative and engenders a dense, black, stupid boredom. Stagnation sets in, social decadence commences. These are the fruits of a doctrine which draws its inspiration from an arbitrary counter-evolutive, and inhuman concept’.
Professor Pierre P. Grasse, aged eighty-two, a member of the Academy of Sciences, published these lines five years ago in the conclusion to a ‘natural history of man’ entitled: Toi, ce petit dieu ! (Albin Michel, 1971).370
In this work, where he sketched the great lines of a philosophy of biology, he is also disturbed by the effects of the ‘counter-selection’: ‘Our societies integrate the retarded, the alienated, the criminals; the pedagogues boost the least intellectually well-endowed, recuperating the mentally debilitated and all the abnormal enter the cycle of reproduction. The result is, necessarily, a fall of the intellectual, moral, even physical health of our contemporaries’.
He advocates a voluntary eugenics: ‘Our species will retain the native qualities of the first Homo sapiens only by following the rules which assure the permanence of the animal species.’
It is indeed more than half a century since Professor Grassé has devoted
himself to the research and teaching of biology. At the Sorbonne, he has occupied the Chair of Evolution for thirty years. Co-author of a monumental Traité de zoologie (Masson), an unrivaled work in the world of which some twenty-eight volumes have appeared between 1948 and 1970, he has overseen the Zoologie volumes published by the Pléïade Collection (Gallimard, 1963) and the large tomes of La vie des animaux (1968–1970), published by Larousse. In the domain of animal sociology, he has introduced such essential notions as ‘social regulation’ or ‘group effect’. Thanks to his theory of ‘stigmergy’, he has been able to explain the collective and adaptive activities of social insects. His works on the structure of the cell are no less important.
As early as 1943, he published an essay entitled Evolution: Facts, experiences, theories. ‘Evolution’, he writes today, ‘is the major problem central to biology. Every attempt to understand the universe and man is influenced by the solution given to it. In addition, it is no longer considered as a hypothesis except by a handful of refractories, ignorant or blinded by dogmatic beliefs. For the atheist as for the practicing Catholic, evolution is a fact. Without taking it into consideration, the living world, the biocosm, remains unintelligible and no longer has any meaning’.
This much is obvious. Disagreement only arises among biologists when it comes to explaining the mechanism.
An Irreversible Fact, Unique Phenomena
Originally we find two theories. That of Darwin, which explains the variations within species by natural selection. By a kind of ‘sorting’ process that works through them, selection favours the individuals best suited to their environment and, consequently, to possible changes in this environment. To the notion of a ‘struggle for life’ resulting in the ‘survival of the fittest’, Darwin adds that of sexual selection, which determines a differential fertility, that is to say (and as would be confirmed by modern ethology) the strongest and most vigorous males fertilise the most numerous and most beautiful females. In the hypothesis of Lamarck, by contrast, it is the transformations of the environment which are translated directly by changes in the organisms of living forms. ‘Need’, writes Lamarck, ‘creates the necessary organ, use strengthens it and makes it grow considerably; lack of use, on the other hand, leads to the atrophy and disappearance of the useless organ’.
With time, the debate became more subtle. In a strict sense, Lamarckism is no longer supported by anyone: since the discovery of the laws of genetics, it has been proven that there is no inheritance of acquired characteristics. Parallel to this, various experiments have made it possible to qualify and specify the scope of natural selection.
Transformism thus appears as an irreversible fact, ‘marked by unique phenomena’: the genesis of branchings, classes, and orders. Its irreversibility is due to: ‘(1) the low probability of reassembling the same objects again and subjecting them to the same physical and chemical conditions; (2) the variability of causes and their effects, which, becoming causes in their turn, change the nature and order of the whole’.
‘The historical human phenomenon’, writes Pierre P. Grasse, ‘differs from the evolutive historical phenomenon because man does not passively undergo the action that the physical, social, and economic environment exercises upon him. He intervenes in events voluntarily, and by changing course with more or less success. Evolution impassively pursues its course, and neither an Alexander nor a Napoleon could change its direction.
On the basis of the work of the Dutch botanist Hugo De Vries (1848–1935), a new theory known as ‘neo-Darwinian’ recognised, along with selection, the role of mutations or sudden alterations of the genetic stock, that have no a priori selective value, but which are hereditary from the outset. According to this theory, also known as ‘synthetic theory’ or ‘neo-mutationism’, mutations ‘create’ genetic varieties, and natural selection is then applied to them.
Hence the formula of Jacques Monod: ‘chance + necessity’. Chance presides over mutations, necessity (invariance) over the laws of heredity.
Most of the great biologists and geneticists of our time (J. B. S. Haldane, Julian Huxley, C. D. Darlington, Waddington, Fisher, Müller, Dobzhansky, Simpson, etc.) have supported the model that Crick and Watson’s discovery of the genetic code in the 1960s appears to corroborate.
Thanks to the work of V. M. Ingram and E. Zuckerkandl on hormones, haemoglobin, and immunoglobulin, it was possible to reconstitute ‘genealogical trees’, both for certain animal species and for humans, which correspond precisely to those anticipated by the study of fossils; some convincing molecular explanations have been proposed.
Macro-evolution
But synthetic theory, although it explains the phenomena of micro-evolution well enough, that is to say, variations of small amplitude like the appearance of races and populations, is much less convincing in regards to macro-evolution: species formation and in particular the bush-like densification371 of large phylum or lineages of development. ‘To vary is one thing, to evolve is another’, remarks Grassé. And we must also explain how we have been able to pass from ‘micro-variations’ to true evolution.
In the simple calculation of probabilities, taking into account the age of the Earth (and the fact that mutations do not occur simultaneously), it is almost inconceivable to attribute the development of a totality as complex as the genealogical tree of all living systems solely to the intervention of purely random variations. Certain facts, such as the adaptation of amphibian reptiles to terrestrial life, with the parallel modifications to the means of reproduction that this implies, are even blatantly inexplicable from such a perspective; likewise, the passage from aquatic or terrestrial life to aerial life and so on. The classical neo-Darwinian theory no longer satisfactorily explains the acquisition in the genotype, during the ‘history’ of the species, of innate behaviours whose existence is now verified.
Recourse to the notion of adaptation according to selective advantage (direct or indirect) does not solve the problem. Taken literally, this theory would imply the quasi-systematic disappearance of the oldest species. And yet, as the biologist Ludwig von Bertalanffy (Theoretische Biologie, 2 vols, Gebrüder Borntraeger, Berlin, 1932–42)372 has remarked, ‘the amoeba, the worm, the insect, the marsupial are as well adapted as the placental mammal; if they were not, they would have disappeared long ago’.
The mutations themselves pose as many problems as they solve. By making appeal to the concept of genetic assimilation, C. H. Waddington (The Strategy of Genes, London, 1957) introduced the surprising idea of ‘virtual mutation’. It has long been observed that a population subjected to a disturbance begins by adapting somatically before adapting genetically. This is called the ‘Baldwin effect’. Given that there is no acquired heredity, G. C. Simpson interpreted the fact as the result of a mutation coming to ‘rescue’ the somatic adaptation at the moment when it would be most useful. C. H. Waddington thinks, more precisely, that a specific conditioning373 selects, from within the population, over a large number of generations, the most effective genetic combinations from existing genes — notably the unused alleles present at low frequency. If one accepts this interpretation, it is no longer possible to say that mutation is entirely random. At the most, we can consider that mutation ‘randomly’ intervenes to trigger a complex mechanism already underpinning it and ‘kept in reserve’.
One can also think, following Jacques Monod, that the input of new genetic information is not only due to the mutations themselves, but also to some of the recombinations that occur at the time of meiosis. The fundamental diversity of the living world (known as the polymorphism of individuals within a single species and the fact of polygenesis, that is to say, the determination of characteristics by several diversely inherited genes) would thus increase ever more, of its own accord, up to the ‘qualitative bounds’ that are equivalent to true mutations.
In addition, there is an obvious relationship of the cybernetic kind between heredity and environment; environmental transformations provoke the selection
of genotypes, and the selected genotype, by its influence on behaviour, provokes in its turn modifications of the environment.
Finally, the mystery is reinforced by the fact that, from one great phylum to another, one detects a structural homology between the evolutionary lineages, even when they develop themselves separately. (Thus the vertebrates have earlier members built on the same model, be it man, dog, bird, whale, etc.) Arthur Koestler (The Ghost in the Machine)374 cited the case of non-placental mammals in Australia. ‘This continent’, writes M. Quentin Debray, ‘has been cut off from the Asiatic continent in the Upper Cretaceous at a time when mammals were tiny creatures like mice. This is why the mammals of Australia are different from ours: they are marsupials. And yet, despite this difference in detail and this complete isolation, Australia’s mammals include moles, wolves, cats, and squirrels that appear to be copies of the corresponding placental mammals. Everything happens as if a complete evolutionary programme had been stored up in the ancestral mouse, determined to some close parameters’. (Les mécanismes de l’évolution, in La Nouvelle Presse médicale, 17 February 1973).375
An ‘Outcry’376
All these considerations justify a certain skepticism against the certitudes of the ‘ultra-Darwinists’. That is why Grassé resisted a chance that looked too much like providence, and asserted, not without reason, that recourse to the selection-mutation mechanism was unsatisfactory.
‘We regard as false’, he writes, ‘the dilemma “or chance or the supernatural” in which the biologists of randomness try in vain to corner their opponents. In fact, there is neither chance nor the supernatural, but laws which regulate living beings, laws whose research is the goal, the raison d’être, of science, which in this affair must have the last word’.
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