Alfred Gierer

What, precisely, are the ‘changing perspectives on reality’ in contemporary scientific thought? The topics of the lecture are the scope and the limits of science with emphasis on the physical foundations of biology. The laws of physics in general and the physics of molecules in particular form the basis for explaining the mechanism of reproduction, the generation of structure and form in the course of the development of the individual organism, the evolution of the diversity and complexity of organisms by mutation and selection, and the control of behaviour by information processing in the nervous system. However, the application of scientific thought to its own foundations reveals some basic limitations in science: indeterminacy in quantum physics, the limits of decidability in mathematics, and, most likely, the limitations of an algorithmic theory of the brain-mind relationship. In all these cases, the application of scientific methods to their own presuppositions leads us to recognize their intrinsic limitations. These limits, in turn, are closely related to fundamental philosophical questions on the relationship between human knowledge and reality. Modern science is consistent with different, though of course not all, interpretations of man and the universe, including the religious interpretations of the universe as God’s creation and man as God’s (mentally creative) image.

Die Beziehung der Entwicklung des Lebens im Weltall - von den einfachsten Formen bis zu Leben mit Geist und Bewusstsein – zu der Physik, wie wir sie aus der unbelebten Natur kennen, ist Thema dieses Essays. Ist die Entstehung des Lebens Zufall, ist es Folge einer physikalischen Logik, die noch zu entdecken ist, oder ist „Lebensfreundlichkeit“ ein eigenes Prinzip des Naturgeschehens, das zum Beispiel offene Naturkonstanten der physikalischen Gesetze festlegt, zu denen die geheimnisvollen Grossen Zahlen der Kosmologie gehören – „The Lore of Large Numbers…“? Wissenschaftlich bleibt diese Frage nicht eindeutig zu klären; intuitiv wird das „Prinzip lebensfreundlich“ der menschlichen Evolution wohl am ehesten gerecht. Dabei ist „lebensfreundlich“ in diesem Artikel nicht psychologisch im Sinne menschlicher Beziehungen gemeint, sondern eine Art Kurzbezeichnung für eine Physik, die im Kosmos irgendwann und irgendwo Leben, auch menschliches Leben mit Geist und Bewusstsein ermöglicht. Der Artikel ergänzt auch Texte des Autors über Physik und Bewusstsein (unter philpapers im Volltext) um physikalische und anthropologische Aspekte der Kosmologie. Anmerkung: Eine frühere Version dieser physikalischen Überlegungen: Gierer, A., The Physical Foundations of Biology and the problem of Psychophysics RATIO XII, 1970, p.47-64 Deutsche Version: RATIO XII, Heft 1, 1970, S.40-54

There is increasing evidence for directional guidance of growing axons by molecular gradients in target tissues. Aside from biochemical studies on gradients and their role, the capability of axons to approach their target position from different aspects of a two-dimensional field is itself an indication for guidance by gradients. According to this criterion, such guidance is expected to be involved not only in map-formation in the visual system but also in targeting of receptor cell axons in the olfactory bulb. In this paper, physico-chemical concepts of visual mapping are adapted to olfactory targeting. In both cases there must be sophisticated processing of graded cues in the growing tip of the axon for growth cone navigation. In visual map formation, a target position is determined by influences of cues depending on the position of axonal origin; in olfactory targeting, however, these influences are expected to be based on properties of the receptor-cell-specific molecules (possibly including the receptor molecule itself), as well as by gene regulation affecting the levels of expression. According to this concept, the main role of molecules expressed in a receptor-cell-type specific manner is not matching specific counterparts on the target tissue, but instead quantitative modulation of growth cone steering for sensing the direction towards the target position.

An abstract in English is included in the download. Wolfgang Pauli war einer der Grossen unter den Physikern des 20. Jahrhunderts, nicht ganz so berühmt wie Heisenberg und Einstein, aber annähernd ebenso bedeutend. Er war es, der bei der Entwicklung der Quantenphysik das sogenannte Ausschließungsprinzip entdeckte und damit den Weg zu unserem physikalischen Grundverständnis der ganzen Chemie eröffnete. Seine Gedanken galten aber auch hintergründigen wissenschaftsphilosophischen Fragen, und die gängigen Auffassungen über die Rolle von Vernunft und Materialismus in der Naturwissenschaft waren ihm zu eng. Er betonte vielmehr, dass wissenschaftliches Verständnis immer wesentlich auch psychisch ist, dass das erlebte Glücksgefühl, welches mit einer Entdeckung verbunden ist, entscheidendes Motiv ist, dass dabei Ordnungen der Natur mit Urbildern unserer Psyche verknüpft werden, und dass eine sinnvolle Weltsicht zwar auch, aber nicht nur durch abendländisches Vernunftdenken zustande kommen kann; er strebte nach einer Verbindung mit einem gefühlten Einheitsdenken in der Tradition der östlichen asiatischen Kulturen. Abschliessend betont der Artikel, wie vielseitig überhaupt die Gedanken der Begründer der modernen Physik im 20. Jahrhundert in Bezug auf Grundfragen des religiösen Denkens waren.

Die Reflexion der Grundlagen der Wissenschaft mit ihren eigenen Mitteln, wie die gedankliche Vermessung des Messprozesses, die in die Begründung der Quantenphysik eingeht, und die logische Analyse der Logik im Rahmen der mathematischen Entscheidungstheorie zeigt schließlich prinzipielle Grenzen des möglichen Wissens auf. Eine Theorie des Leib-Seele-Zusammenhangs läuft auf das Bewusstsein von Bewusstsein hinaus und ist damit von dem gleichen Typ des Selbstbezugs, der auf prinzipielle Grenzen der Erkenntnis verweist. Die moderne Naturwissenschaft ist offen für damit verbundene philosophische Fragestellungen, und das Deutungsspektrum ist weit. Nicht zuletzt besteht Deutungsfreiheit auch in Bezug auf Kontingenz, auf unverfügbare, nicht voraussehbare, nicht ableitbare Einzelereignisse, die unser Leben wesentlich bestimmen. Eine Weltanschauung der Sinnleugnung oder des Sinnverzichts ist logisch möglich, naturwissenschaftlich zwingend ist sie nicht, und Kriterien der Lebenskunst würde sie kaum gerecht werden.

In 1972, we proposed a theory of biological pattern formation in which concentration maxima of pattern forming substances are generated through local self- enhancement in conjunction with long range inhibition. Since then, much evidence in various developmental systems has confirmed the importance of autocatalytic feedback loops combined with inhibitory interaction. Examples are found in the formation of embryonal organizing regions, in segmentation, in the polarization of individual cells, and in gene activation. By computer simulations, we have shown that the theory accounts for much of the regulatory phenomena observed, including signalling to regenerate removed parts. These self- regulatory features contribute to making development robust and error-tolerant. Furthermore, the resulting pattern is, to a large extent, independent of the details provided by initial conditions and inducing signals.

Unlike Aristotelian physics with its teleological notions, modern physics was developed exclusively in relation to the nonliving domain. This raised the question as to whether mechanics applies to organisms, and if so, to what extent. From the seventeenth century on, mechanistic ideas became prominent in biological and medical theory. Contemporary biology explains essential features of life on the basis of physical laws and processes. This does not prove, however, that the early mechanists were essentially right. In the eighteenth century, following Cartesian notions of mind-body separation and preformation theories of organismic development, they tended to exclude major biological questions rather than answering them. It was those who insisted on the organizational features of organisms, like Stahl and Wolff, who paved the way for solutions to such crucial problems as the psychological basis of human nature and behavior and the generation of form in the course of reproduction. Though they underrated the potentials of a future, extended physics for understanding biology, their case against reductionist exclusion should not be considered outdated even today.

A summarizing English version on “Theory of Innovation and the Evolution of General Human Capabilities, such as Cognition-based Empathy” is included in the download. Den biologisch modernen Menschentyp charakterisieren sehr allgemeine Fähigkeiten, wie begriffliche Sprache, strategisches Denken und kognitionsgestützte Empathie. Neurobiologisch kann Empathiefähigkeit als eine Verbindung von Repräsentationen von Mitmenschen mit dem je eigenen Gefühlszentren im Gehirn angesehen werden. In Grundzügen ist sie vor vielleicht 100 000 Jahren als Folge von Mutationen der Erbsubstanz DNA entstanden. Für solche genetische Innovationen spielten wohl nicht nur lokale Veränderungen des Genoms eine Rolle, sondern auch seltene größere Umordnungen, besonders neue Zufallskombinationen von Regelbereichen in der DNA. Dies könnte in seltenen Einzelfällen eine Art Weichenstellung für eine neue Richtung der Evolution bewirken, die dann in vielen kleinen Schritten ausgeprägt wurde. Interessant ist die Analogie solcher biologischer mit technischer Innovation: Auch in ihr, Beispiel Dampfschiff, spielt die (seltene) Neukombination von Grundfähigkeiten eine Initialrolle für die Ausbreitung einer Innovation.

Understanding cooperative human behaviour depends on insights into the biological basis of human altruism, as well as into socio-cultural development. In terms of evolutionary theory, kinship and reciprocity are well established as underlying cooperativeness. Reasons will be given suggesting an additional source, the capability of a cognition-based empathy that may have evolved as a by-product of strategic thought. An assessment of the range, the intrinsic limitations, and the conditions for activation of human cooperativeness would profit from a systems approach combining biological and socio-cultural aspects. However, this is not yet the prevailing attitude among contemporary social and biological scientists who often hold prejudiced views of each other's notions. It is therefore worth noticing that the desirable integration of aspects has already been attempted, in remarkable and encouraging ways, in the history of thought on human nature. I will exemplify this with the ideas of the fourteenth century Arab-Muslim historian Ibn Khaldun. He set out to explicate human cooperativeness - "asabiyah" - as having a biological basis in common descent, but being extendable far beyond within social systems, though in a relatively unstable and attenuated fashion. He combined psychological and material factors in a dynamical theory of the rise and decline of political rulership, and related general social phenomena to basic features of human behaviour influenced by kinship, expectation of reciprocity, and empathic emotions.

The book on "Science and the image of man" pursues different pathways by way of which science contributes to the understanding of human beings as a species: the scope and limits of human cognition are revealed by the history and the mental structure of science in a more precise manner than by any other cultural effort. Insights into the evolution and function of the human brain elucidate the origin and the range of general human capabilities, such as language, self-representation and strategic thought. These capabilities are the products of biological evolution as well as preconditions of cultural development, which is based on traditions rather than on genetic inheritance. At the metatheoretical level, modern science reveals its own intrinsic limitations and is open to different cultural and philosophical interpretations. Human consciousness is a product of evolution of the human brain, and yet it may not be possible to decode the mind-brain relation fully by finite procedures. One of the specifically human capabilities is cognition-based empathy; it may have evolved in conjunction with strategic thought, because it facilitates the prediction of the behaviour of others, but it also motivates altruistic behaviour. Stereotyped controversies between sociologists and social biologists on human ethics appear somewhat outdated; there is a biological basis in humans not only for egoism but, to a limited extent, also for cooperativity and solidarity. Ethical demands should respect the biological conditions of the human species. They imply that cooperativeness is a real but limited resource. It requires activation, but excessive moralism is counterproductive. -/- -/-.

A strong motivation for the human genome project was to relate biological features to the structure and function of small sets of genes, and ideally to individual genes. However, it is now increasingly realized that many problems require a "systems" approach emphasizing the interplay of large numbers of genes, and the involvement of complex networks of gene regulation. This implies a new emphasis on integrative, systems theoretical approaches. It may be called 'holistic' if the term is used without irrational overtones, in the general sense of directing attention to integrated features of organs and organisms. In the history of biology, seemingly conflicting reductionist and holistic notions have alternated, with bottom-up as well as top-down approaches eventually contributing to the solutions of basic problems. By now, there is no doubt that biological features and phenomena are rooted in physico-chemical processes of the molecules involved; and yet, integrated systems aspects are becoming more and more relevant in developmental biology, brain and behavioural science, and socio-biology. -/- .

Ancient Greek philosophers were the first to postulate the possibility of explaining nature in theoretical terms and to initiate attempts at this. With the rise of monotheistic religions of revelation claiming supremacy over human reason and envisaging a new world to come, studies of the natural order of the transient world were widely considered undesirable. Later, in the Middle Ages, the desire for human understanding of nature in terms of reason was revived. This article is concerned with the fundamental reversal of attitudes, from "undesirable" to "desirable", that eventually led into the foundations of modern science. One of the earliest, most ingenious and most interesting personalities involved was Eriugena, a theologian at the Court of Charles the Bald in the 9th century. Though understanding what we call nature is only one of the several aspects of his philosophical work, his line of thought implies a turn into a pro-scientific direction: the natural order is to be understood in abstract terms of "primordial causes"; understanding nature is considered to be the will of God; man encompasses the whole of creation in a physical as well as a mental sense. Basically similar ideas on the reconciliation of scientific rationality and monotheistic religions of revelation were conceived, independently and nearly simultaneously, by the Arab philosopher al-Kindi in Bagdad. Eriugena was more outspoken in his claim that reason is superior to authority. This claim is implicit in the thought of Nicholas of Cusa with his emphasis on human mental creativity as the image of God's creativity; and it is the keynote of Galileo's "Letter to the Grand Duchess Christina" some 800 years later, the manifesto expressing basic attitudes of modern science.

The explanation of nature in theoretical terms was first postulated and initiated by Ancient Greek philosophers. With the rise of monotheistic religions, however, curiosity about our transient world was widely regarded as contributing nothing to salvation. There was a decline in natural philosophy, which lasted for several centuries and was then reversed both in Islamic philosophy and in Christian theology in the Middle Ages. At this point, the "Book of Nature" was recognized as a complement to the Book of Revelation. Originally, Aristotelian philosophy played the leading part in this process, but only after Aristotelian physics was substituted by experimental mathematical mechanics did it become possible for modern science to develop. General laws of physics form the basis of the explanation of events in space and time, including life processes. However, modern science has also revealed its own limitations. The scope and limits of scientific knowledge allows for different philosophical, cultural and religious interpretations of human beings and the universe. The history of science demonstrates erratic and persistent developments, but the long-term retrospective view discredits extreme forms of relativism and structuralism. Science appears as a construct of the human mind, and yet it is capable of generating valid explanations of nature. In the book more attention than usual is given to Cusanus (Nikolas de Cusa). -/- .

In biological terms, human consciousness appears as a feature associated with the func- tioning of the human brain. The corresponding activities of the neural network occur strictly in accord with physical laws; however, this fact does not necessarily imply that there can be a comprehensive scientific theory of conscious- ness, despite all the progress in neurobiology, neuropsychology and neurocomputation. Pre- dictions of the extent to which such a theory may become possible vary widely in the scien- tific community. There are basic reasons - not only practical but also epistemological - why the brain-mind relation may never be fully “decod- able” by general finite procedures. In partic- ular self-referential features of consciousness, such as self-representations involved in strate- gic thought and dispositions, may not be resolv- able in all their essential aspects by brain analy- sis. Assuming that such limitations exist, objec- tive analysis by the methods of natural science cannot, in principle, fully encompass subjective, mental experience.

Diese Schrift enthält eine Reihe von sieben Artikeln, in der es um die Beziehung der Wissenschaften zu aufgeklärten, liberalen Formen religiöser Vorstellungen geht. Im Gegensatz zu verbreiteten Ansichten zumal des vorigen Jahrhunderts führt die moderne Naturwissenschaft zu einer zwar weitgehenden, aber prinzipiell nicht vollständigen Erklärung der Wirklichkeit. Sie kann die Rätselhaftigkeit der Welt für uns Menschen nicht aufheben; die Grundfähigkeiten des menschlichen Denkens sind schließlich nicht nur Gegenstand der Wissenschaft, sondern auch Voraussetzungen jeder wissenschaftlichen Tätigkeit. Auf der „meta-theoretischen“, nämlich der philosophischen, kulturellen und religiösen Ebene bleibt die Welt mehrdeutig; wir dürfen und können wählen. Nach meiner Ansicht sprechen dabei Weisheit und Lebenskunst für eine pro-religiöse Einstellung; verbindlich kann und soll sie aber nicht sein. Die Artikel folgen dieser Gedankenspur. Sie sind voneinander unabhängig entstanden, sollen auch unabhängig lesbar sein und sind dazu als Volltext einbezogen. Etwas an Wiederholungen in der Reihe ist so nicht zu vermeiden, und dafür bitte ich um Nachsicht. Am Beginn steht eine kurze Antwort des Autors zur Frage „Was ist der Mensch?“, welche die Berlin-Brandenburgische Akademie der Wissenschaften etwa achtzig Personen gestellt hat. Es folgt ein Artikel zur biologischen Entstehung der höheren geistigen Fähigkeiten unserer Spezies „Mensch“, insbesondere der kognitionsgestützten Empathie. Zentraler Aspekt ist in den weiteren Überlegungen das menschliche Bewusstsein; es gibt prinzipielle, erkenntnistheoretisch robuste Gründe gegen die Möglichkeit einer vollständigen naturwissenschaftlichen Erklärung. Schon der geniale mittelalterliche Theologe Meister Eckhart hat den Urgrund des menschlichen Bewusstseins als göttlich angesehen. Unter den modernen Naturwissenschaftlern gehe ich exemplarisch auf Wolfgang Pauli ein, der neben Physik und Logik besonders die psychischen Voraussetzungen wissenschaftlicher Entdeckungen betont. Im Bezug auf Religion zeigte er Sympathie für östliche Gedankenwelten, liebte Schopenhauer, der den Buddhismus für westliche Denker wieder entdeckt hatte. Sodann erkläre ich meine Gründe für pro-religiösen „metaphysischen Optimismus“ – das göttliche Heil ist für Alle da - und das nicht nur im Kontext des Christentums. Nach diesem mehr persönlichen Artikel (ohne Zitate!) schließe ich mit einer systematischen Analyse von Aspekten moderner Biologie, die verschiedene, sowohl agnostische wie auch pro-religiöse Deutungen ermöglichen, und argumentiere für Offenheit der Erörterung. The basic issue of this book on “Science, the enigma of consciousness, and pro-religious ideas” is the relation of modern science that encompasses, among its topics, its own intrinsic limitations, to enlightened, liberal versions of religion. The relation allows for more than one logically consistent interpretation on the “metatheoretical“, that is on the philosophical and cultural level. This includes religious as well as agnostic views. Choices and preferences are mainly a matter of wisdom and art of living, and not just of knowledge, and this may lead us towards a pro-religious option.

A network of gene regulation organized in a hierarchical and combinatorial manner is crucially involved in the development of the neural network, and has to be considered one of the main substrates of genetic change in its evolution. Though qualitative features may emerge by way of the accumulation of rather unspecific quantitative changes, it is reasonable to assume that at least in some cases specific combinations of regulatory parts of the genome initiated new directions of evolution, leading to novel capabilities of the brain. These notions are applied, in this paper, to the evolution of the capability of cognition-based human empa­thy. It is suggested that it has evolved as a secondary effect of the evolution of strategic thought. Development of strategies depends on abstract representations of one’s own pos­sible future states in one’s own brain to allow assessment of their emotional desirability, but also on the representation and emotional evaluation of possible states of others, allowing anticipation of their behaviour. This is best achieved if representations of others are con­nected to one’s own emotional centres in a manner similar to self-representations. For this reason, the evolution of the human brain is assumed to have established representations with such linkages. No group selection is involved, because the quality of strategic thought affects the fitness of the individual. A secondary effect of this linkage is that both the actual states and the future perspectives of others elicit vicarious emotions, which may contribute to the motivations of altruistic behaviour.

Der Text ist eines von achtzig Kurzessays zum Thema „Was ist der Mensch“, zu denen unsere Arbeitsgruppe „Humanprojekt“ der Berlin-Brandenburgischen Akademie der Wissenschaften eingeladen hat. So genau Aussagen inhaltlicher Naturwissenschaft oft sind, auf der metatheoretischen Ebene bleibt die Gesamtheit unseres Wissens, und damit auch die Stellung des Menschen in der Natur deutungsfähig und deutungsbedürftig; sie ist mit verschiedenen, natürlich nicht mit allen, philosophischen, kulturellen und religiösen Interpretationen vereinbar; erkenntnislogisch gesehen dürfen und können wir wählen. Worum es dabei eigentlich geht, ist Lebenskunst, die Frage nach der guten Art zu leben, und deshalb plädiere ich im Zweifelsfall für metaphysischen Optimismus. Der Mensch kann fast im platonischen Sinne das Mentale und damit die Beziehung seines Bewusstseins zur gedanklichen Ordnung des Naturgeschehens betonen, und er muss sich auch nicht die religiöse Frage verbieten, was diese Verbindung für ihn bedeuten kann. Was die Ethik angeht, so ist Gemeinsinn eine wertvolle, aber knappe Ressource unserer biologischen Spezies „Mensch“, die eher behutsam und mit Rücksicht auf natürliche Anlagen des Menschen zu aktivieren ist.

• Aggregates of previously isolated cells of Hydra are capable, under suitable solvant conditions, of regeneration forming complete animals. In a first stage, ecto- and endodermal cells sort out, producing the bilayered hollow structure characteristic of Hydra tissue; thereafter, heads are formed (even if the original cell preparation contained no head cells), eventually leading to the separation of normal animals with head, body column and foot. Hydra appears to be the highest type of organism that allows for regeneration of the entire structure from random cell aggregates. The system is particularly useful for studying cell interactions, tissue polarity, pattern formation, and cell differentiation.

While many different mechanisms contribute to the generation of spatial order in biological development, the formation of morphogenetic fields which in turn direct cell responses giving rise to pattern and form are of major importance and essential for embryogenesis and regeneration. Most likely the fields represent concentration patterns of substances produced by molecular kinetics. Short range autocatalytic activation in conjunction with longer range “lateral” inhibition or depletion effects is capable of generating such patterns (Gierer and Meinhardt, 1972). Non-linear reactions are required, and mathematical criteria were derived to design molecular models capable of pattern generation. The classical embryological feature of proportion regulation can be incorporated into the models. The conditions are mathematically necessary for the simplest two-factor case, and are likely to be a fair approximation in multi-component systems in which activation and inhibition are systems parameters subsuming the action of several agents. Gradients, symmetric and periodic patterns, in one or two dimensions, stable or pulsing in time, can be generated on this basis. Our basic concept of autocatalysis in conjunction with lateral inhibition accounts for self-regulatory biological features, including the reproducible formation of structures from near-uniform initial conditions as required by the logic of the generation cycle. Real tissue form, for instance that of budding Hydra, may often be traced back to local curvature arising within an initially relatively flat cell sheet, the position of evagination being determined by morphogenetic fields. Shell theory developed for architecture may also be applied to such biological processes.

The book (in German) on “Solar Energy – challenge for research, development and international co-operation” is the report of a study group of the Akademie der Wissenschaften zu Berlin. It reviews solar thermal, photovoltaic, and bio mimetic solar energy techniques; prospects of de-central techniques in developing countries; transport and storage of solar energy; and chances for cooperation with Arabic countries and countries of the South of the former Soviet Union. The prospect of large scale energy production in arid areas, and the modern potentials of conducting electricity over long distances by high-voltage DC transmission (V, 2.1) are particularly relevant for the concluding section. Political chances as well as risks were considered for reliable long term cooperation with various Arab countries on these issues. The recommendations appear to be still appropriate 25 years after the book was published, particularly the political advice in favour of cooperation between Europe and suitable countries of the Maghreb. The global time scale of implementation (discussed in chapter I, 7.2) is of the same (high) magnitude as that of other major changes in the history of technology, such as the substitution of sailing ships by steamboats which took almost a century.