Chapter 5 Chapter 3 Biology in Change-2

The rapid rise of certain centers of research is common in the history of biology.The universities in northern Italy in the 16th and 17th centuries are one example, the rise of some universities in Germany in the second half of the 19th century is the second example, and Paris from Buffon (1749) to Cuvier (1832) is the third example .The particular contributions made by the leading scientists of starry Paris are presented in the relevant chapters, and Lamarck (1744-1829) is singled out here because his theory of evolution (first published in Discours in 1800) proposed) a radical departure from the old tradition.

It is often said that only young people have revolutionary new thinking, but Lamarck did not show his heresy until he was over fifty.His study of geology led him to realize that the earth is very old and that environmental conditions on it are constantly changing.He was well aware of the adaptation of living things to their environment, and he was bound to draw only this conclusion.In order to adapt to the ever-changing environment, the organism itself must change.He confirmed this conclusion by comparing the fossils of Tertiary strata molluscs with modern molluscs.Based on these, Lamarck proposed the theory of transformation (1809), that is, organisms have an inherent tendency to strive to improve themselves to adapt to environmental changes.All these explanations, however, failed in fact, because he relied on traditional beliefs such as the inheritance of acquired traits.Despite Cuvier's harsh criticism, Lamarck's writings influenced many readers, including Chambers, the author of Le Remains (with vestigial organs).For all the censure he faced, Lamarck undoubtedly paved the way for Darwin.For his multifaceted contributions to botany, to the classification of invertebrates, and to the knowledge of biology, Lamarck has a place and deserved honor in the history of biology, even without his theory of evolution.

Because of Lamarck's theory of evolution (1800, 1809) and his coinage of the word "biology" in 1802 (Burdach in 1800, Treviranus in 1802), it is sometimes thought that he Introducing biology into a new era.The broad biological sciences do not support this claim.Lamarck's theory of evolution had little impact, and the coinage of the word "biology" did not create the "science" of biology. Biology was practically no science in the early eighteenth century, although there were already Lamarck's grand project (Grasse, 1940) and some works of the German school of natural philosophy.These are but the blueprints for a biology to be built.At that time there were only natural history and medical physiology.The unification of biology still awaits the establishment of evolutionary biology and the development of disciplines such as cytology.

Lamarck's formidable rival was Cuvier (1769-1832), whose contributions to science were innumerable.He established paleontology (fossilology), and his analysis of the paleontebrate fauna of the Paris Strata contributed as much to stratigraphy as did the work of William Smith in England.I have already mentioned Cuvier's research in comparative anatomy and rejected the concept of a ladder in nature.When Geoffroy Saint Hilaite attempted to revive the concept of a unified structural scheme for the entire animal kingdom, Cuvier attacked it devastatingly.The so-called "Academy dispute" (1831) between him and Jeffrey was not a question of evolution (as it is sometimes thought) but a question of whether the structural design of all animals could be reduced to a single primitive pattern .

Cuvier had an enormous and mixed influence on his time.He inspired the study of comparative anatomy (more influential in Germany than in France) and paleontology, yet his conservative ideas also influenced generations of French biologists.Therefore, although the idea of ​​evolution was first put forward by Lamarck, it has gone through a more difficult process before being accepted in France than in other scientifically enthusiastic European countries.Cuvier played a paradoxical role in the history of the theory of evolution.He used all his knowledge and logical power to oppose Lamarck, the original representative of evolutionary thought, but his own research in comparative anatomy, systematics and paleontology provided the basis for subsequent believers in the theory of evolution (evolutionism). most valuable evidence.

3.6 The rise of science from the 17th century to the 19th century A lot happened in the three hundred years from the 17th to the 19th centuries, yet cause and effect were often impossible to ascertain. It was common for scholars using Latin to travel and give lectures between countries in the late Middle Ages and the Renaissance. However, this situation decreased sharply after the 17th century, and the popularity of Latin also declined significantly.The result has been a rise in nationalist (or statist) tendencies in science, fueled by the use of national languages ​​in academic literature.Works published in foreign languages ​​are used less and less as references.This narrow regional concept reached its peak in the nineteenth century, so that each country has its own rational background and mental state.

There is perhaps no other era in Western history where the difference in national temperament is more evident than in the period from 1790 to 1860.Britain is dominated by empiricism.It is based on the nominalist tradition of William of Ockham and developed mainly by John Locke; eighteenth-century chemists Hull, Blake, Cavendish, and Priestley All pursue this kind of empiricism.In France there was first the violence of the revolution, followed by the restoration of the monarchy, and then the extreme reaction.Although natural theology and the church did not play any role in it, the conservatism can be clearly felt through Cuvier.In Germany the situation is completely different.After the mass trials and seizures of power in the seventeenth and eighteenth centuries there was a new enthusiasm, first of the classical cult, then of the school of natural philosophy (initiated by Schelling, Okun, Carlos, etc.) Represents the Romantic movement.Similar to France, physical theology ceased to play a role after about 178O.In England, on the contrary, natural theology was completely dominant.

Science, especially biology, was neglected and studied almost entirely by amateurs.The above is the background of the era of the rise of Darwinism. The professionalization of science began in France about after the revolution of 1789, and roughly in Germany (Mendelsohn, 1964), but in Great Britain as late as the mid-nineteenth century.Most of our current concepts of science and scientific research were developed in German universities. Teaching laboratories were established in Germany in the 1930s (by Purk-inje, Liebig, Leuckart, etc. respectively).German universities placed more emphasis on research and awarded higher degrees in the 19th century than in other countries.There is no contradiction between purely theoretical science and applied knowledge in Germany, and the German university system is very similar to the craft apprenticeship system.This greatly encouraged the spirit of struggle and achievement.

When science began to flourish in the United States and institutes were established in universities, the German university system was mainly adopted. The phenomenon resumed in the late 19th century with the massive movement of scientists between countries, in which the Italian Naples marine life station played an important role.Science once again became truly cosmopolitan (international), which had a major impact on the development of experimental biology in the United States (Alien, 1960). Finally, the relevant regional issues should be mentioned.From the end of the 15th century to the 19th century, almost all the major advances in biology came from six or seven countries.The Biological Research Center was initially in Italy, then moved to Switzerland, France, the Netherlands, then Sweden, and finally Germany and the UK.There is a constant flow of scientific personnel, and there is always one country that leads the way, mainly for economic or social reasons.For example, one of the reasons why Germany took the lead in biology in the 19th century was that zoology, botany and physiology were first established in German universities (Owen was the first professional biology clergyman or doctor in Britain to teach), zoology It's professionalized.

Until the 19th century, scientific progress was very patchy and its branches often had only one researcher at a time so there were so few Darwinian natural selection theories.He was taken aback when he found that others (thoughts. When many large and began to professionalize biology, each family, so that scientific writings appeared, the increase in the number of specialists changed the nature of biological publications greatly. Change. Juliussachs pointed out that this change occurred in the first half of the 19th century in his history of botany. The scientific publications in the 18th century were characterized by a large number of pages and large volumes, such as Shifeng’s natural history, (Histoir. naturelle ), Linnaeus' "Natural System" (Sy-stema Naturae), and in the 19th century began to publish shorter monographs, and more importantly, short magazine articles. This required more new journals. To In 1830 there were only the publications of the Royal Society, the French Academy of Sciences and other academies and journals such as Gottinger Wissenschaftliche Nachrich-ten. In the nineteenth century there were the Zoological Society, the Linnean Society, the Geological Society of London. Some professional societies such as the Society began to publish journals. There were also "Annalsand Magazine", "American Journal of Science", German "Journal of Zoology" and "Annals of Botany", etc. Although there is no history of biological journals (history books), but there is no doubt that the Journal of Biology has had an important impact on the development of biology.

As modern biology became more and more specialized, Chromosomes, Evolution, Ecology, Journal of Animal Psychology (to name just a few) served as meeting points for newly developed subdisciplines.Far more articles (and the number of pages of articles) have been published in the present few decades than in the entire previous period of biological history.This broadens and deepens biology greatly, yet if we were to name ten of the most fundamental biological questions, we would probably find that most of them were asked fifty or even a hundred years ago of.Even if it is impossible for historians to trace every issue or every debate all the way back to the 1980s, such an approach would certainly provide a basis for understanding how things are going now. 3.7 The schism of biology in the 19th century The development of comparative research around the 19th century provided for the first time an extremely favorable opportunity for the unification of biology, that is, to build a bridge between naturalists and anatomy-physiologists.Cuvier's emphasis on function reinforces this connection.But only a few biologists took advantage of this opportunity, most notably Johannes Muller (1801-1858), who in the 1730s moved from pure physiology to comparative embryology and invertebrate morphology.Muller's own students, however, widened the rift in biology by actively promoting a physicist-reductionist approach to the study of living phenomena that was ill-suited for a naturalist. After the 1840s there was less contact between naturalists and physiologists than before, and after 1859 between scholars who studied evolutionary (ultimate) causes and physiological (recent) causes.This polarized situation can be said to be in a sense a continuation of the sixteenth-century practice of dissociation between herbal gatherers-naturalists and physician-physiologists, but at this time, especially after 1859, the two However, the differences in contradictions and interests of readers are more obvious.Two well-defined classes of biology - evolutionary biology and functional biology - exist side by side.They compete for talent and material resources.Often argue because it is difficult to understand the other person's point of view. Some historians of science are keen to distinguish different periods according to dominant modes (Kuhn), knowledge (Fouca-ult) or research traditions.This approach does not work in biology.Since the late seventeenth century, even within a single discipline or specialty of biology, two seemingly incompatible models can coexist, such as preformation versus epigenesis, mechanism versus vitalism, medical physics And medical chemistry, deism and natural theology, catastrophe and uniformitarianism, etc.This makes interpretation very difficult.On the basis of the spirit of the time, that is, on the basis of all the conditions of reason, culture and spirit of the time, how can the emergence and maintenance of completely opposite views be explained?There are two additional problems for historians.The various controversies I have mentioned above do not agree with each other, and they end (for whatever reason) at different times.To make matters worse, the sequence of events is often very different in different countries.The school of natural philosophy, for example, was largely confined to Germany, and natural theology dominated science in England during the first half of the nineteenth century, and in France and Germany as early as the eighteenth century. Foucault's view of dressing up the progress of science (and its background) as a continuous series of knowledge obviously does not hold true in the real world. What we see is two sets of phenomena.First, the gradual changes in the structure, institutionalization, and norms of what we today call science; and second, the definite periods of the various branches of science.The best I can do, therefore, is to provide a somewhat regrettably disconnected sketch of the progress of the various biological disciplines.Further research will no doubt shed light on whether and to what extent states of affairs in the various branches of biology are connected, and how scientific progress is related, if at all, to the general rational and social context.It is a pity that such connections are rarely established in my statements. Two categories of biology were very clearly established in the mid-19th century: physiological (functional) biology and evolutionary biology. I will first introduce these two types of biology before discussing recent developments. No other discipline in biology is more frequently and fiercely contested with opposing points of view than physiology.Extreme mechanism holds that an organism is just a machine, explained only in terms of motion and forces.The extreme vitalism holds that the organism is controlled entirely by a sensitive soul, if not a thinking one.From the time of Descartes and Galileo to the end of the 19th century, these two views have been attacking each other and arguing endlessly in physiology. The mechanistic view of the physicists was greatly strengthened by the popular philosophical writings of three natural scientists.They were Karl Vogt, Jacob Moleschott, Ludwig Buchner, generally known as the German scientific materialists (Gregory, 1977).Regardless of the name, they are devout spiritualists and staunch atheists at the same time.Because of their uncompromising critique of vitalism, supernaturalism, and other assorted non-materialist views; they became, so to speak, the "watchdogs" of physiology, relentless against any non-physico-chemical views or explanations. attack. There were two reasons for the sudden upsurge in reductionist physicalism in physiology in the mid-nineteenth century.First, because vitalism was still widespread at the time, it naturally aroused resistance.Another reason was that, due to the high reputation of physical science at the time, physiologists could raise their voices by adopting incompatible physicalistic and mechanistic explanations.Helmholtz was the leader of this craze, and he put forward the following slogan at the meeting of naturalists held in Innsbruck, Germany in 1869: "The ultimate goal of natural science is to reduce all the processes of nature to these Process the movements of the fundamentals and explore their dynamics, that is, reduce them to mechanics." Such a reductive view is often available in the biological field of recent causes, and attempts at such an analysis are generally illuminating, if not unsuccessful.However, because this reductionist view was very influential at the time, it was also cited in many biological issues, especially in evolutionary biology, but it was completely inapplicable in evolutionary biology.Helmholtz, for example, studied at one time the physical sciences and at the other the biological sciences; since physiological processes are really chemical or physical processes in the final analysis, it was easy for him to study both.But his trendy concept has also been referenced in some subdisciplines of biology where it doesn't fit.Haeckel (1866) in his General Morphology In the preface of the first book, it is mentioned that his task is to raise the science of biological organisms to the level of inorganic matter science through the basis of mechanics.Nageli titled his famous book on evolution The Mechano-Physiological Theory of Origin (1884), at about the same time, Ru (W. Roux) changed the name of embryology to "developmental mechanics". These attempts above have two major weaknesses.First, "mechanistic" or "mechanistic" is almost never clearly defined, sometimes taken literally, as in the study of functional morphology; yet sometimes referred to simply as the opposite of "supernatural".Another weakness is that the advocates of mechanism never distinguish between immediate and ultimate causes, and fail to understand that the mechanistic view, which is essential in the study of immediate causes, is usually absent in the analysis of evolutionary (ultimate) causes. significance. The methodology of physiology underwent great changes in the 19th century, including more precise use of physical methods, notably Helmholtz and Ludwig; and greater use of chemical methods.A large number of medical physiologists, animal physiologists and chemical physiologists study each physiological process and the function of each organ and gland separately.Human physiology as a whole is practiced in various animal and plant physiology laboratories, although human physiologists make extensive use of animal experiments (including vivisection). The 1859 publication caused hardly a ripple in the world of physiology, which is the study of recent causes. The theory of evolution did not die with Lamarck's death in 1829.It is still a popular idea in Germany thanks to the School of Natural Philosophy as well as a few zoologists such as Schaaffhausen, Unger.In Britain it was revived by Chambers' famous The Remnant, a popular defense of evolution, though slammed by some professional biologists.However, natural theology still dominated in England at that time and was supported by almost all famous scientists including Charles Lyell.The above is the background of the times when Darwin put forward his new theory in 1859. Evolution includes adaptation to change and diversity.In his theory Lamarck actually ignored diversity altogether, arguing that new species of organisms were continually formed by spontaneous generation.Darwin read Leyle's "Principles of Geology" and his own studies of the fauna of Galapagos and South America have focused attention on the origin of diversity, that is, the origin of new species.His theory of evolution is about the theory of "common ancestor", that all organisms ultimately come from a very small number of original ancestors, or very likely from a single original ancestor.Humanity is thus inevitably part of the overall evolutionary flow and pulled from the lofty status conferred on it by Stoicism, Christian teaching, and Cartesian philosophy.This common ancestor theory can be regarded as Darwin's first revolution. Darwin's theory of evolutionary causes was equally revolutionary.First of all, he denied the mutation theory of essentialism and insisted on absolute gradual evolution.He also rejected Lamarck's view that evolution is due to a spontaneous internal drive to perfection, proposing that each evolutionary change has its own strict and individual cause.The cause appeared to Darwin as a two-step phenomenon. The first step was the continual generation of countless hereditary variations. Darwin quite frankly admitted that he had no idea how such variations arose, and he regarded them as A "black box".The second step is the differential survival and reproduction ("selection") among the excess individuals produced in each generation.This natural selection is not an "accident" (Darwin is often accused of using such language), but arises strictly (in a probabilistic sense) from the interaction of genetic endowment and environmental conditions.This theory of evolutionary causes was Darwin's second revolution. He took a strictly materialistic view of design (the harmony of the biological world) and thus, according to his opponents, "deposed God". Darwin's first revolution, the doctrine of common ancestry, was soon accepted by almost all sensible biologists (although some of his original opponents, such as Sedgwick, Agassiz, and death will not admit).The situation of Darwin's second revolution was very different. It was not until the period of "evolutionary synthesis" (that is, the comprehensive theory of evolution) around 1936-1947 that biologists recognized that natural selection was the only trending factor in evolution. Darwin's theory of common ancestor is one of the most instructive.It has prompted many zoologists, anatomists and embryologists to study the relationship between the putative common ancestors and their possible characteristics.This is a long-term task, and until now is far from complete; because the direct relatives and putative common ancestors of many major groups of plants and animals are still unknown.Oddly enough, comparative anatomy is almost entirely limited to the use of Darwin's theory of common ancestry, an undeniable involuntary continuation of the idealistic morphological tradition.Few have asked about the causes of structural changes in phylogenetics. It was not until the 1950s that comparative morphology was consciously transformed into evolutionary morphology due to the establishment of links with ecology and behavioral biology and the question of why was constantly being asked. Haeckel's theory of reenactment, that an organism passes through the morphological stages of its ancestors as its embryo develops, greatly contributed to comparative embryology. Kova-levsky discovered that sea squirts are close relatives of vertebrates, both of which belong to the chordate phylum, which is a representative result of this type of research. Comparative embryology asks almost exclusively questions of evolutionary biology, so it is extremely inappropriate to classify it with functional biology. Goette, His, Ru opposed this one-sided view and tried to establish an embryology dedicated to the study of recent causes, a purely mechanistic embryology rather than a purely inferred and historically studied embryology.This new embryology, which Ru characterizes as "developmental mechanics," dominated embryology from the 1980s until the 1930s.But new embryology quickly ran into trouble when it was discovered that an egg that splits in half after the first cleavage could develop into two complete embryos.Can a machine work if it is cut in half?This unexpected self-regulation effect forced Driesch, who completed the above experiment, to embrace the extreme "vitality theory" and proposed a non-mechanical "entelechy".Even those embryologists who do not follow Driesch tend to adopt interpretations tinged with "vitalism", such as Spemann's "organizer".It is worth noting that although embryologists are not anti-evolutionists, they are almost unanimously opposed to Darwinism.Then again, so did most biologists at the time. Around 1870 there was a slight shift in the direction of biological research in Europe.At this time, it has been 40 years since J. Muller turned from physiology to comparative embryology, and many new situations have occurred during this period: Darwin’s influence is expanding; the microscope has really become a powerful tool for biological research; the gradual professionalization of British science has begun; Liberating from Cuvier's influence.However, the progress of the different disciplines of biology has been extremely uneven.Due to the rapid development of microscope technology and fixation and staining methods, the research on cells and nuclei was the fastest growing from the 1770s to the 1890s.During this stage the fertilization process is finally figured out. In 1884, Weissmann, Strasburger and others proved that the nucleus contains genetic material (Darwin's flood theory was put forward before this).Subsequent research on cells was more in-depth, leading to the establishment of various genetic theories, among which the detailed analysis and synthesis of Weissman (1892) was the most outstanding.Except for Nageli (1884) and Hertwig, the above-mentioned scholars all advocate particle inheritance (Particulate inheritance), and except for De Vry (1889), they all focus on the developmental aspect of inheritance.They now appear to be incorrect on two important assumptions.First, in order to explain differentiation and quantitative inheritance, they assumed that the determinants of a certain trait could be represented by multiple identical granules in the nucleus, and these granules could be distributed unequally during cell division.Second, they argue that these determinants can be directly translated into the structure of the developing organism.The first hypothesis was later refuted by Mendel, and the second by Avery and molecular biology. In 1900, de Vry and Collens rediscovered Mendel's law and proved that each parent provided only one genetic unit for each segregated trait, which was later called gene (see Chapter 16 and Chapter 17).Most of the principles of transmission genetics were worked out in the next 20 years, under the leadership of Bateson, Punnet, Ceunot, Currens, Johnson, Kessel, East, Baur, Morgan et al. .All the evidence they gathered indicated that the genetic material was unchanging, that heredity was "hard."Changes in genetic material are discrete and called "mutations".Regrettably, de Vry and Bateson used the discovery of Mendelian inheritance as the basis for a new theory of sudden change, denied Darwin's theory of gradual evolution, and more or less underestimated the theory of natural selection. This explanation of evolution is totally unacceptable to naturalists.Their understanding of the nature of species and of geographic variation had advanced enormously during the preceding fifty years, and it was especially important that they began to recognize the nature of populations and developed "population thinking," according to which the traits of each individual is unique.The evidence they presented fully confirmed Darwin's conclusions that evolution proceeded gradually (except for polyploidy) and that speciation was normal geographic speciation.The literature of the taxonomists (ultimately referred to in the "New Systematics") has been sadly ignored by the experimental biologists, just as much of the literature on genetics after 1910 has been ignored by the naturalists.The result is a lamentable information gap between these two armies of biologists. The above-mentioned difficulties and misunderstandings were finally resolved during 1936-1947, and a unified theory of evolution was formed, often called "evolutionary synthesis" (Mayr and Povine, 1980).Dubzhansky, Chairman, Meyer, Huxley, Simpson, Stebbins and others believe that major evolutionary phenomena such as speciation, evolutionary trends, the origin of progressive miracles, and the hierarchy of all systems can be used in this century In the 1920s and 1930s, it was explained by the mature genetic theory.Except for additional emphasis and for a more precise analysis of mechanisms, synthetic evolution has become the modus operandi today. 3.8 Biology in the Twentieth Century At the same time that the theory of evolution was becoming more sophisticated, entirely new fields of biology emerged, notably ethology (the comparative study of animal behavior), ecology, and molecular biology. After the pioneering (but mostly neglected) work of Darwin (1871), Whitmann (1898) and O. Heinroth (1910), the real development of ethology is due to K.Lorenz (1927 and onwards) with Niko Tinbergen after him.While previous animal psychologists have focused most of their attention on the immediate causes of behavior, and generally on the learning process in one animal experiment, ethologists have concentrated on the relationship between genetic programs and subsequent experience. Interaction.They have been most successful in studying species-specific behaviors, especially courtship, which are largely controlled by closed programs.The debate between Lorenz and Von Holst and between Lorenz and Schneirla and Lehrman on the degree of genetic influence on behavior appears in some respects to have been that between Rei-marus and Condillac in the 18th century and Altum and Brehm in the 19th century reenactment.The debates within the behavioral field of the 1940s and 1950s are now a thing of the past. Behaviorists do not disagree in principle, but mainly in emphases. Behavioral research is currently mainly expanded in two ways.On the one hand, it integrates with neurophysiology and sensory physiology, and on the other hand, it combines with ecology: study species-specific behavior in the sense of natural selection in a certain animal's habitat (living environment).In addition, many behaviors involve the exchange of signals, most often between individuals of the same species. This science of signaling and information (Semiotics) and the role of communication in the social structure of species is also currently the most active part of behavioral research. The 20th century is generally considered to be the era of the birth of ecology.The importance of studying environmental issues has indeed never been felt so urgently since the 1960s, yet ecological thought goes back to ancient times (Gasken, 1967).It is very prominent in the works of Buffon and Linnaeus, and plays an important role in the travel landscapes of famous explorers (such as Forster and his sons and Humbert) in the 18th and 19th centuries.Because the ultimate purpose of these people is no longer to collect and describe species but to explore the interaction between biological organisms and their surrounding environment.Humbert is known as the father of plant ecogeography, but later his interests turned almost exclusively to geophysics.Many of Darwin's arguments and considerations are well suited for ecology textbooks. The term "ecology" was coined by Haeckel in 1866 as the science of "the chores of nature". Semper wrote the first general ecology.In subsequent years various studies of "living conditions of living things" Or research groups in "clusters" of different kinds of organisms have little connection. Morbius (1877) published his classic work on oyster-banks. Hensen and others focus on marine ecology.Some are interested in studying plant ecology, others in freshwater biology (mainly the ecological aspects). Ecology has long remained static and descriptive, with thousands of articles discussing the number of species and their individuals in a given area.Certain scholars have come up with various terms used in the field, some so eccentric that even the spade for digging up plants has been renamed "geotome". Ecology has regained momentum thanks to three developments.One is Lotka-Volterra's calculations for studying cyclical population size changes due to predator-prey relationships and for broader growth, decline, and cyclical population size changes.The second is the special emphasis on competition, thus establishing the principle of competitive exclusion and Gause's experimental verification.Later, under the leadership of David Lack and Robert MacArthur, the study of species competition became an important branch of ecology.It is a borderline discipline between ecology and evolutionary biology because competitive relationships determine not only the presence or absence of species, their relative frequencies, and overall species diversity, but also the adaptations of those species to change during evolution.The third is to pay attention to the problem of energy flow, especially the energy flow of fresh water and marine organisms.Exactly how much computer-based modeling contributes to the understanding of interactions in ecosystems has been debated. Since many ecological factors ultimately have behavioral characteristics, such as resistance to predation, feeding tactics, habitat selection, habitat identification, environmental evaluation, etc., it can even be said that, at least as far as animals are concerned, most ecological research is currently related to behavioral issues.Moreover, all studies in plant ecology and animal ecology ultimately involve natural selection. As the analysis of physiological and developmental processes becomes more detailed and complex, it is increasingly believed that many of these processes can ultimately be reduced to the role of biological molecules.Previous studies of these biomolecules were limited to the fields of chemistry and biochemistry.Biochemistry originated in the 19th century, but at first it did not have a clear boundary with organic chemistry, and biochemical research was generally carried out in chemical research institutions.Early biochemistry did not have much to do with biology, it was only the chemistry of compounds extracted from living organisms, and at most it was the chemistry of important compounds related to biological processes.There are some biochemistries that still have this property until now.Molecular biology is derived not only from biochemistry but also from physiology (Florkin, 1972ff; Fruton, 1972, Leicester, 1974). Certain achievements in biochemistry are of particular importance to biologists.One of them is to elucidate some metabolic pathways step by step, such as the Krebs cycle and finally demonstrate that each step of this metabolic pathway is controlled by a specific gene.This kind of research work is no longer purely in the category of biochemistry, but it is customary and more reasonable to call it molecular biology.分子生物学所研究的真正是分子的生物学，包括分子的修饰变化，分子的相互作用，甚至分子的进化历史。 另一项重要的事态发展是认识到胶体化学的某些假定或设想是不切实际的，而很多重要的生物性物质是由高分子（量）的聚合物组成。20年代和Staudinger的名字密切联系着的这一事态发展，后来大大地促进了人们对胶原蛋白质，肌肉蛋白的了解，特别重要的是对DNA，RNA的了解。聚合后的有机分子具有晶体的某些性质，它们复杂的三维结构可以用X-射线晶体分析法加以说明（Bragg，Perutz，Wilkins）。通过这些研究清楚地表明高分子的三维结构，即其形态，是它们的功能的基础。虽然大多数生物性高分子最终是由有限数量的同样原子，主要是碳，氢、氧、硫、磷、氮原子聚合而成，但是都具有极其特殊的、有时是完全独特的性质。对这些高分子三维结构的研究大大有利于对其性质的认识。 分子生物学家已经弄清了千百种生物性物质的结构及其有关代谢途径，然而他们的研究很少有像阐明了遗传物质的化学本质那样激动人心。早在1869年米歇尔就已发现大部分细胞核物质含有核酸。随后（十九世纪八十、九十年代）有人认为核素（即核酸）就是遗传物质，然而这种假说后来并没有被普遍接受（参阅第十九章）。一直等到1944年艾弗里（Avery）及其同事论证了肺炎球菌的转化因子是DNA之后，有关的研究方向才发生了转变。虽然不少生物学家立即充分认识到艾弗里这一发现的重要意义，但是他们并不具备深入研究这一具有极大魔力的分子的技术手段和技术诀窍。问题很清楚，这个看来很简单的分子（当时认为和蛋白质比较起来是简单的）怎么会在受精卵的细胞核中携带着控制发育过程的全部信息？只有知道了DNA的确切结构才能开始探究它是怎样执行其独特功能的。为了解决DNA分子结构的问题当时在很多研究所之间展开了激烈的竞赛，英国剑桥卡文迪什研究所的华生和克里格于1953年脱颖而出取得了胜利。应当指出的是，如果他们两个人没有成功，则在几个月或几年之后别的人也会解决这个问题。 每个人都听说过双螺旋的故事，但并不是每个人都充分地了解这一发现的重要意义。 DNA并不直接参与有机体的发育或生理功能活动，而只是提供一套指令（遗传程序），这套指令被译成相应的蛋白质。DNA是一幅蓝图，在身体的每个细胞中==全相同，并通过受精作用一代传给一代。DNA分子的关键组成部分是四个碱基对（总是一个嘌呤碱和一个嘧啶碱）。由三个碱基对构成的序列（三联体）确定翻译成哪一种氨基酸，而由三联体组成的序列则决定形成哪一种肽。DNA的三联体译成氨基酸是1961年DNA双螺旋结构以及遗传密码的发现是生物学中一项非常重要的突破。它彻底澄清了生物学中一些最含糊不清的问题并提出—些明确的新问题，其中有的就是目前生物学研究的前沿。它阐明了生物有机体为什么和任何无生命物质根本不同。在非生物界中绝对没有遗传程序，而生物界的遗传程序却贮存有30亿年历史的信息。同时这一纯粹唯物主义的解释也阐明了活力论者一再声称无法用化学和物理学解释的许多现象。确实这仍然是一种物理学家的解释，但较之前几个世纪的笼统机械论的解释却又是深奥复杂精细入微得多。 与分子生物学纯粹化学性的发展的同时还有另一种性质的事态在发展。30年代电子显微镜的发明使人们对细胞结构有了完全新的认识。19世纪学者称之为原生质并认为是生命的基本物质的东西被发现原来是具有各种不同功能的细胞器组成的极其复杂的系统。 其中大多数是作为特殊高分子的“生活环境”的（生物）膜系统。分子生物学目前已进入许多急待开发的新领域，其中有一些在医学上相当重要，这里不能—一详细介绍。 3．9生物学史上的主要时代 历史编纂学中的传统方式是划分时代（时期）。例如西方世界史就被分成三个时代： 古代，中世纪，和现代。中世纪和现代的分界线通常走在公元1500年左右，更精确地说是在1447年与1517年之间。人们常说在这个时期中赋予新的西方世界以其特有风格的决定性事件发生了（或者说决定性动向开始出现了）：发明了活字印刷术（1447年），文艺复兴（一般认为开始于1453年康士坦丁堡陷落时），发现新大陆（1492年），以及宗教改革（1517年）。即使可以怀疑在中世纪与现代之间提出明确界限的合理性，然而上述事态却标志着急剧的变化。另外，在1447年以前的两百年中毕竟也发生过许多重要的事件。 科学史家也同样试图在科学历史上划定明确的时期。哥伯尼和Vesalius的主要着作都在1543年出版一事一直被人重视，更重要的是从伽利略（1564—1642）到牛顿（1642一1727）的那个时期的事态发展被称为“科学革命”。（Hall，1954）。在这个时期中物理科学和哲学（培根和笛卡尔）也都有意义重大的进展，然而在生物学中却并没有轰动世界的变化发生。就一个爱挑剔的人来看，维萨纽斯的《人体结构》除了插图在艺术上的卓越性而外很难说是一部革命性的专着。它的重要性根本无法和哥伯尼的革命性着作《天体运行论》相比（Radl，1913：99—107）。 16世纪是一个令人困惑而又矛盾的时期，一个气质、风格迅速变化的时期。它既经历了人道主义的鼎盛年代（以荷兰的Erasmus的着作为代表），路德的宗教改革（1517），也见到了激烈的反宗教改革运动（耶苏教派的建立）和科学革命的兴起。区别于经院哲学流派的、真正的亚里斯多德的重新发现对生物学产生了明显的影响（表现在切查皮诺与哈维的着作中）。虽然和机械科学的繁荣无法相比，但16世纪末和17世纪初生理学和博物学都取得了一定程度的进展。 一切迹象表明当时物理科学和生物科学的事态发展毫不一致。在生物学中也无从划定明确的意识形态的或观念上的分期，正如John Greene（1967）在评论Foucault的《语言与事物》一文中很有见地的指出的那样。Jacob的《生命的逻辑》（1970）一书也因袭了Foucault的传统，但他并没有采纳Fouc－ault的分期。Holmes（1977）后来又对Jacob的分期提出了质疑。 所有的上述学者都没有认真地面对这样一个问题；为什么不同的学者在生物学历史的分期问题上作出的结论竟然如此不一致。是不是因为这些时期完全是想像的从而不同的学者可以按不同的方式作出武断的划分？这种认识看来并不正确。某些历史学家所确认的时期的确是真实的。我认为这个问题有另一种答案，也就是说这些时期并不是普遍一律的。不同的国家有不尽相同的时期，不同的科学和生物学的不同学科更是不同，特别是在功能生物学与进化生物学之间。这两类生物学的变化之间很少相关性。 生物科学缺乏像物理科学那样的统一性，其中每门学科各有自己的发轫与兴旺年代纪。直到17世纪左右，我们现在称之为生物科学的只包括两个联系非常疏松的领域，博物学与医学。后来在十七、十八世纪博物学才明确地分为动物学与植物学，虽然从事这方面工作的许多研究人员，包括林奈与拉马克，常在这两门学科间自由流动。与此同时，医学中的解剖学，生理学，外科与内科日益分离，逐渐形成单独学科。20世纪蔚为主导的遗传学，生物化学，生态学和进化生物学在1800年以前还根本不存在。这些学科的兴起和暂时挫折的历史将是本书随后各章的主要论题。 分类学家，遗传学家或生理学家对生物学史会有各自的分期，正像德国人，法国人或英国人对待历史分期的态度不同那样。历史不够整齐划-显然是令人惋惜的，然而这才是历史。遗憾的是，这使得历史学家的任务更为困难，因为他必须同时研究五、六种不同的当时的“研究传统”。由于学术分期的问题很容易引起争论，对它们的认识也只是新近的事，因而对生物学各个领域还缺乏足够的分析。 生物学的每一门学科，例如胚胎学，细胞学，生理学或神经病学等都有其各自的停滞期和迅速发展期。人们有时会提出这样的问题：生物科学历史上有没有这样一个时期，就像物理科学在科学革命时期那样经历了激剧的转变方向的变化？答案是没有。生物学的每门学科确实都有各自新开端的年代：胚胎学，1828；细胞学，1839；进化生物学，1859；遗传学，1900。虽然每门学科有各自的周期，然而并没有范围广泛的普遍革命。 即使在1859年出版，但实际上对实验性生物学并没有影响。以种群思想代替本质论在进化生物学中是如此重要，但几乎在一百年以后才触及到功能生物学。DNA结构的阐明（1953）对细胞生物学和分子生物学产生了强大影响，而对大部分机体生物学则并无关系。 生物科学中最类似于一次革命的年代大致在1830—1860年，这是生物学史上最震撼人心的时代（Jacob，1973：178）。就在这一段时期内，由于冯贝尔（K·E·von Baer）的着作使胚胎学发生了飞跃；由于布朗发现了细胞核以及施旺，许来登及魏尔和的着作为细胞学的发展提供了动力；在Helmholtz，duBois－Rey－mond，Ludwig，Bernard领导下新生理学开始成型；Wohler，Liebig等为有机化学奠定了基础；由于Muller，Leuckart，Siebold，Sars的研究工作使无脊椎动物学的基础得到更新；最重要的则是达尔文与华莱士提出了关于进化的新学说。上述的各种事态发展并不是一项联合行动的一部分，事实上多数是独立开展的。这些发展主要是由于科学的职业化，显微镜的改进以及化学的迅速进展。然而其中有一些却是某一天才的出现的直接结果。 3．10生物学和哲学 在古希腊时代科学和哲学是不分的。哲学就是当时的科学，特别是从爱奥尼亚哲学家泰勒斯（Thales）以后更是如此。有一些数学家兼工程学家，如阿塞米德，另有一些医生兼生理学家，如希波克拉底以及后来的盖伦，他们更接近于是真正的科学家。但是当时的一些着名哲学家，如亚里斯多德，则既是哲学家又是科学家。 到了经院哲学的末期哲学和科学才开始分离。解剖学家如维萨纽斯，物理学家兼天文学家如伽里略，植物学家兼解剖学家如切查皮诺，以及生理学家如哈维主要都是科学家，虽然他们之中有些人具有浓厚的亚里斯多德哲学观点或反对这种哲学观点。哲学家也随之转变成为愈益“纯粹的”哲学家。笛卡尔既是科学家又是哲学家的极少数人之一。 而贝克莱、霍布斯，洛克，休谟则已经是纯粹哲学家。康德可能是最后一位对科学（人类学和宇宙学）作出非凡理论贡献的哲学家。在他之后则是科学家和数学家对哲学作出贡献（赫塞尔，达尔文，赫姆霍尔兹，马赫，罗素，爱因斯坦，海森堡，洛兰茨）而不是相反，由哲学家作出科学贡献。 十八、十九世纪哲学正处于鼎盛时期。亚里斯多德的堡垒被笛卡尔攻破、接着笛卡尔的堡垒又被洛克、休谟和康德攻克。奇怪的是，不管他们在其它方面的观点多么不同，这个时期的所有哲学家都在本质论的框架内提出问题。19世纪哲学界出现了一些新动向，其中孔德的实证主义（Comtes positivism）最为重要，它是科学的哲学。在德国以Vogt，Buchner，Moleschott为代表的强有力的还原论唯物主义很有影响，如果没有其它理由，单是它的过份夸张就促使整体论者，突现论者，甚至活力论者十分活跃。它始终一贯地对一切形式的二元论和超自然主义的坚决抵制产生了长远影响。 上述哲学动向在生物学中对生理学和心理生物学产生的影响最大，也就是说对研究近期原因的学科影响最大。这些哲学与生理学研究之间关系的本质还没有恰当地进行分析过。尽管有不少反对意见，但是看来在发现过程中哲学只起很小的作用（如果不是微不足道的作用的话），而在解释性假说的形成中，哲学信条与原则所起的作用则很大。 在哲学家中，莱布尼茨（G·W·Leibniz，1646—1717）和当时的物理学家哲学家不同，他特别关心将自然界作为一个整体来认识。他指出借助于第二手的，物理的原因来解释生物界现象是多么不合实际。虽然他自己的答案（事先建立的和谐与理由充分的定律）并不是所寻求的解答，但是他所提出的问题却使随后几代的哲学家（包括康德）大伤脑筋、困惑不已。尽管他具有数学天才，他却清楚地意识到自然界并不仅仅只能用（数）量来说明并成为首先认识到性质的重要性的学者之一。在本质论不连续概念占统治地位的年代，他却强调连续性。他对“自然界阶梯”的兴趣（虽然他将之看作是静态的）为进化思想铺平了道路。他对启蒙运动的哲学家布丰、狄特罗、毛帕修斯等人的思想产生了深刻影响，并通过他们影响了拉马克。他可能是伽利略-牛顿传统的本质论、机械论思想的最重要的反抗势力的代表人物。 进化生物学的哲学基础远不如功能生物学的那样清楚。生命定向性（“高等”、“低等”）概念可以回溯到亚里斯多德和“自然界阶梯”（Lovejoy，1936），然而种群思想则在哲学（晚期唯名论）中并没有多少立足之处。关键性的对历史重要性的认识（与物理定律的无时间性相比较）则确实来自哲学（Vico，Her－der，莱布尼茨）。承认历史的重要性就几乎不可避免地导致承认发展过程。对谢林（及自然哲学派），黑格尔，孔德，马克思以及斯宾塞来说，发展很重要。发展思想的重要性在Mandelbaum（1971：42）为历史主义（historicism）下定义时就讲的很好：“历史主义认为对自然界现象的正确理解以及对其价值的正确评断只能通过按它所处的地位及其在发展过程中所起的作用来考虑”。 这样就会认为进化学说来源于这种思想，但是并没有多少证据证明这一点，除了斯宾塞的进化论而外，斯宾塞的进化论并不是达尔文，华莱士，赫胥黎或海克尔等人的基本思想。出人意外的是历史主义似乎从来没有和进化生物学发生密切关系（也许除人类学而外）。历史主义和逻辑实证主义是两种完全不相容的思想。只是到了晚近“历史性叙述”的概念才被某些科学哲学家接受。然而在1859年以后很快就发现定律的概念在进化生物学中（就这一点来说凡是研究由时间左右的过程的科学如宇宙学，气象学，古生物学，古气候学、海洋学都如此）远不及历史性叙述的概念有用。 笛卡尔哲学的反对者所提的问题是机械论者从来未曾提出过的。这些问题很尴尬地表明机械论者的解释是多么贫乏。他们不仅提出涉及时间和历史的问题，而且越来越多地提到为什么的问题，也就是探索“终极原因”。到了18世纪末期和19世纪早期，正是在德国对牛顿的追随者的机械论观点（这种观点只满足于提出有关近期原因的简单问题）发起了决定性的反击。即使是生物学领域以外的学者，例如Herder，也对之产生了有力的影响。遗憾的是，这种努力（歌德与康德都曾参与）并没有涌现出建设性的模式。相反，这一运动却被某个奥肯，谢林和卡洛斯（“自然哲学派”）掌握，他们的幻想只会被专门家嘲笑不已，他们的笨拙解释在现代读者看来真是难于卒读。但是他们的某些基本兴趣和爱好与达尔文的十分相近。由于对“自然哲学派”的极端片面性深恶痛绝，反对机械论的博物学者转向于不提出任何问题的简单描述，因为这种领域是广阔无限的，这正如某些有才识的学者很快就指出的那样，在理智上却是劳而无功的。 在1800年以后哲学对科学究竟是否作出过贡献的问题一直有争议。很自然，哲学家一般对此作了肯定的回答，而科学家正相反，他们的答案是否定的。然而毫无疑问，达尔文研究方案的制订是受到哲学影响的（Ruse，1979；Hodge，1982）。近几十年来哲学显然已撤退到亚科学（metascience）方面，即研究科学方法论，语意学，语言学，符号学以及在科学边缘的其它课题上。 3．11现代生物学 如果要用最简单的文字说明现代生物学的特征，答案将是什么？当前生物学给人印象最深的也许是它的单一化，它的统一。前几个世纪的着名论战实际上已经解决。形形色色的活力论已全部被否定，而且几代以来已没有虔诚的信徒。许多互相竞争的进化学说逐一地被排弃，由一个否定本质论、否定获得性遗传，否定直生论和骤变论的综合进化论代替。 越来越多的生物学家已经认识到功能生物学和进化生物学并不是“非此即彼”的，而且只有确定了近期原因和终极（进化）原因这两者之后生物学问题才算真正解决。因此现在有许多分子生物学家在研究进化问题，也有许多进化生物学家研究分子问题。他们之间的相互了解比二十五年前要广泛得多。 过去的25年也是生物学最终从物理科学解放出来的年代。现在已普遍承认不仅生物系统的复杂程度和非生物界的属于不同的数量级，而且由历史性进化形成的遗传程序也是非生物界所没有的。程序目的性过程和业已适应的系统，由于这种遗传程序，才有可能而这在物理系统中并不存在。 突现过程、即在复杂的等级结构中较高层次出现未曾料到的新性质，在生物系统中较之非生物系统更加无比重要。突现过程不仅将物理科学与生物科学区分开，而且也把这两类科学的策略和解释模式区分了开来。 关于生物学中目前的主要问题是什么这个问题还无法回答。因为生物学的每一门学科都有其末解决的主要问题，即使是像系统学，生物地理学，比较解剖学这样一些古老的传统学科也是如此。而且，目前议论最多也最棘手的都是涉及复杂系统的问题。这些问题中最简单的、也是目前分子生物学最注意的是真核生物染色体的结构与功能。为了解答这个问题就必须弄清楚各种不同的DNA（如为可溶或不溶蛋白质编码的DNA，不起作用的DNA，中度重复和高度重复DNA等等）的功能及其彼此之间的相互作用。虽然从化学上来说所有这些DNA在原则上都相同，但有的形成结构物质，有的具有调节功能，另一些则被某些分子生物学家认为丝毫不起作用（“寄生性”）。这些可能都是真实的、正确的，但是对像我这样的彻底的达尔文主义者来说却并不是非常具有说服力。我相信整个复杂的DNA系统在不远的将来就会研究清楚。 对于更复杂的生理系统的认识进展速度问题我并不很乐观，例如控制分化的系统以及神经系统的运转。如果不将这些复杂系统分解成为其组成部分就无法解决这些问题，然而在分析过程中毁坏了系统后就很难弄清楚系统中一切相互作用的本质及其控制机制。 要充分认识复杂的生物系统需要很长的时间和耐性，而且只有通过还原论者和突创论者的联合努力才能实现。 生物学目前已经是如此广泛，如此多样化因而已不再可能完全由一种特殊的方式来驾御，例如林奈时期的物种描述，达尔文以后时期的种系发生的建立，或二十年代的发育力学。的确，目前分子生物学特别活跃，然而神经生物学，生态学和行为生物学也正处在兴旺发达时期。即使是比较不活跃的学科也有各自的杂志刊物（包括新的出版刊物），组织专题讨论，并一直不断地提出新的问题。而尤其重要的是，尽管从外表上看来日益分化，生物学在实质上却较之过去几百年更加趋于统一。