The paper addresses the formation of striking patterns within originally near-homogenous tissue, the process prototypical for embryology, and represented in particularly purist form by cut sections of hydra regenerating, by internal reorganisation of the pre-existing tissue, a complete animal with head and foot. The essential requirements are autocatalytic, self-enhancing activation, combined with inhibitory or depletion effects of wider range – “lateral inhibition”. Not only de-novo-pattern formation, but also well known, striking features of developmental regulation such as induction, inhibition, and proportion (...) regulation can be explained on this basis. The theory provides a mathematical recipe for the construction of molecular models with criteria for the necessary non-linear interactions. It has since been widely applied to different developmental processes. (shrink)

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. -/- . (shrink)

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. (shrink)

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. (shrink)

The essay is an English version of the German article "Wissenschaftliche Rationalität, menschliches Bewusstsein und pro-religiöse Ideen". It discusses immanent versus transcendent concepts in the context of the art of living, as well as the understanding of human consciousness in the context of religion. Science provides us with a far reaching understanding of natural processes, including biological evolution, but also with deep insights into its own intrinsic limitations. This is consistent with more than one interpretation on the “metatheoretical“, that is (...) on the philosophical and cultural level, including liberal, enlightened forms of religion 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, in my view, supports metaphysical and anthropological optimism as expressed in liberal pro-religious ideas. Within Christian theology, metaphysical optimism and openness are most characteristic for the ideas of “apokatastasis” – “salvation for all” - repeatedly condemned as heretical, but also widely supported from early Christianity to modern times. (shrink)

Upon separation of the protein from the nucleic acid component of tobacco mosaic virus by phenol, using a fast and gentle procedure, the nucleic acid is infective in assays on tobacco leaves. A series of qualitative and quantitative control experiments demonstrates that the biological activity cannot depend on residual proteins in the preparation, but is a property of isolated nucleic acid which is thus the genetic material of the virus.

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. (shrink)

Applying mild methods of preparation, part of the ribosomes of rabbit reticulocytes are found in aggregates (later called polyribosomes) of up to six ribosomal units. Upon treatment with RNA-ase, they desintegrate into single ribosomes. The fast-sedimenting aggregates are found to be more active in protein synthesis in terms of incorporation of radioactive amino acids, whereas the single ribosomes are more receptive to stimulation by the artificial messenger RNA poly-U. The findings indicate that the linkage of ribosomes into aggregates is due (...) to the messenger RNA. They support a tape-reading mechanism of protein synthesis whereby growth of the peptide chain is accompanied by shifting the active site of the ribosome from one coding group of nucleotides of the messenger RNA to the next. (shrink)

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. (shrink)

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. (shrink)

Modern science, based on the laws of physics, claims validity for all events in space and time. However, it also reveals its own limitations, such as the indeterminacy of quantum physics, the limits of decidability, and, presumably, limits of decodability of the mind-brain relationship. At the philosophical level, these intrinsic limitations allow for different interpretations of the relation between human cognition and the natural order. In particular, modern science may be logically consistent with religious as well as agnostic views of (...) humans and the universe. These points are exemplified through the transcript of a discussion between Kurt Gödel and Rudolf Carnap that took place in 1940. Gödel, discoverer of mathematical undecidability, took a proreligious view; Carnap, one of the founders of analytical philosophy, an antireligious view. By the time of the discussion, Carnap had liberalized his ideas on theoretical concepts of science: he believed that observational terms do not suffice for an exhaustive definition of theoretical concepts. Then, responded Gödel, one should formulate a theory or metatheory that is consistent with scientific rationality, yet also encompasses theology. Carnap considered such theories unproductive. The controversy remained unresolved, but its emphasis shifted from rationality to wisdom, not only in the Gödel-Carnap discussion but also in our time. -/- . (shrink)

An English translation of the essay and an extended introduction are included in the download. In diesem Essay geht es um ein religionsfreundliches Selbst- und Weltverständnis, das die Reichweite der menschlichen Vernunft ebenso wie deren intrinsische Grenzen achtet. In dem weiten Feld wählen wir hier Betrachtungen des mittelalterlichen Philosophen und Theologen Meister Eckhart aus. Eckhart (ca.1260-1338) gilt vielen als Mystiker, anderen als Philosophen des Christentums. Er war wohl Beides. Philosophisch ist seine Lehre, die einzelne menschliche Seele habe einen göttlichen, unvergänglichen (...) Urgrund; eher mystisch die These, dieser Urgrund bedarf einer „Gottesgeburt“ in der Seele, ein Loslassen von allen Bestrebungen, einschließlich dem Bestreben, sich gottgefällig zu verhalten. Mir geht es hier nur um den philosophischen Aspekt mit Betonung auf Erkenntnis. (shrink)

Within the sedimentation diagram of infective RNA preparations isolated from Tobacco Mosaic Virus, undegraded molecules form a sharp peak with a molecular weight corresponding to the total RNA content of the virus particle. Degradation kinetics by ribonuclease is of the linear, single-target type, indicating that the RNA is single-stranded. The intact RNA of a virus particle thus forms one big single-stranded molecule. Quantitative evaluation of the effect degradation by RNA-ase on the infectivity of the RNA shows that the integrity of (...) the entire molecule is required for its biological activity. (shrink)

Validity of physical laws for any aspect of brain activity and strict correlation of mental to physical states of the brain do not imply, with logical necessity, that a complete algorithmic theory of the mind-body relation is possible. A limit of decodability may be imposed by the finite number of possible analytical operations which is rooted in the finiteness of the world. It is considered as a fundamental intrinsic limitation of the scientific approach comparable to quantum indeterminacy and the theorems (...) of logical undecidability. An analysis of these limits, applied to dispositions of future behaviour, suggests that limits of decodability of the psycho-physic relation may actually exist with respect to brain states with self-referential aspects, as they are involved in mental processes. Limits for an algorithmic theory of the mind-body problem suggested by this study are formally similar to other intrinsic limits of the scientific method such as quantum indeterminacy and mathematical undecidability which are also related to self-referential operations. At the metatheoretical level, hard sciences, despite their reliability, universality and objectivity, depend on metatheoretical presuppositions which allow for multiple philosophical interpretations. -/- . (shrink)

The short paper introduces the concept of possible branches of double-stranded DNA (later sometimes called palindromes): Certain sequences of nucleotides may be followed, after a short unpaired stretch, by a complementary sequence in reversed order, such that each DNA strand can fold back on itself, and the DNA assumes a cruciform or tree-like structure. This is postulated to interact with regulatory proteins. -/- .

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. -/- . (shrink)

The generation of viral mutants in vitro was demonstrated by treatment of the isolated RNA of Tobacco Mosaic Virus by nitrous acid. This agent causes deaminations converting cytosine into uracil, and adenine into hypoxanthine. Our assay for mutagenesis was the production of local lesions on a tobacco variety on which the untreated strain produces systemic infections only. A variety of different mutants are generated in this way. Quantitative analysis of the kinetics of mutagenesis leads to the conclusion that alteration of (...) a single out of the 6000 nucleotides of the viral RNA is sufficient for causing a mutation. (shrink)

The introductory personal remarks refer to my motivations for choosing research projects, and for moving from physics to molecular biology and then to development, with Hydra as a model system. Historically, Trembley’s discovery of Hydra regeneration in 1744 was the begin¬ning of developmental biology as we understand it, with passionate debates about preformation versus de novo generation, mechanisms versus organisms. In fact, seemingly conflicting bottom-up and top-down concepts are both required in combination to understand development. In modern terms, this means (...) analysing the molecules involved, as well as searching for physical principles underlying development within systems of molecules, cells and tissues. During the last decade, molecular biology has provided surprising and impressive evidence that the same types of mol¬ecules and molecular systems are involved in pattern formation in a wide range of organisms, including coelenterates like Hydra, and thus appear to have been “invented” early in evolution. Likewise, the features of certain systems, especially those of developmental regulation, are found in many different organisms. This includes the generation of spatial structures by the interplay of self-enhancing activation and “lateral” inhibitory effects of wider range, which is a main topic of my essay. Hydra regeneration is a particularly clear model for the formation of defined patterns within initially near-uniform tissues. In conclusion, this essay emphasizes the analysis of development in terms of physical laws, including the application of mathematics, and insists that Hydra was, and will continue to be, a rewarding model for understanding general features of embryogenesis and regeneration. -/- -/- . (shrink)

Biological evolution and technological innovation, while differing in many respects, also share common features. In particular, implementation of a new technology in the market is analogous to the spreading of a new genetic trait in a population. Technological innovation may occur either through the accumulation of quantitative changes, as in the development of the ocean clipper, or it may be initiated by a new combination of features or subsystems, as in the case of steamships. Other examples of the latter type (...) are electric networks that combine the generation, distribution, and use of electricity, and containerized transportation that combines standardized containers, logistics, and ships. Biological evolution proceeds, phenotypically, in many small steps, but at the genetic level novel features may arise not only through the accumulation of many small, common mutational changes, but also when distinct, relatively rare genetic changes are followed by many further mutations. In particular, capabilities of biologically modern man may have been initiated, perhaps some 150 000 years ago, by one or few accidental but distinct combinations of modules and subroutines of gene regulation which are involved in the generation of the neural network in the cerebral cortex. It is even conceivable that it was one primary genetic event that initiated the evolution of biologically modern man, introducing some novel but subtle feature of connectivity into the cerebral cortex which allowed for meta-levels of abstraction and upgraded modes of information processing. This may have set the stage for the evolution of integrated but diverse higher capabilities such as structured language, symbolic thought, strategic thought, and cognition based empathy. (shrink)

Socioeconomic inequalities are functions not only of intrinsic differences between persons or groups, but also of the dynamics of their interactions. Inequalities can arise and become stabilized if there are advantages (such as generalized wealth including “human capital”) which are self-enhancing, whereas depletion of limiting resources is widely distributed. A recent theory of biological pattern formation has been generalized, adapted and applied to deal with this process. Applications include models for the non-Gaussian distribution of personal income and wealth, for overall (...) economic growth in relation to inequalities and for effects of uncoupling strategies between developing and developed countries. Note added after publication: The equations (14) for the model of the income distribution, with its characteristic non-Gaussian extension towards higher incomes (fig.4), are closely related to the Fokker-Planck equation that is widely applied in many fields of physics. (shrink)

Abstract in English: The short essay is about impressive philosophical ideas of the great German dramatist Friedrich Schiller (1749-1805). In his “letters on the aesthetic education…” he critisizes, with respect to human behaviour, too much reason and too stringent principles, leading to a neglect of positive emotions such as empathy; he argues in favour of an aesthetic lifestyle. This is supported by biological as well as mental aspects of human self-understanding. My article follows these lines of thought in a sequence (...) of sections: The nature of human beings – a permanent topic of science, philosophy and the arts. The professional dramatist as temporary philosopher- Schiller’s “Letters on the aesthetic education…”. Against an “egoism of reason”, in favour of empathy. Basic human capabilities allow for an objective view on nature. Positive versus negative effects of the division of labour…and thoughts on a new “wholeness” with an aesthetic lifestyle. After Schiller’s philosophical phase, back to new dramas on stage – Wallenstein’s fragile sense of empathy. Evolution, empathy and the “art of living” – survival of the fittest or survival of the nicest? Self-contradictory self-images – Demetrius the illusiory tsar as rival of Boris Godunow. -/- Deutsche Zusammenfassung: Für uns Menschen gehört zum „guten Leben“, dass wir uns sowohl als Natur- wie auch als Kulturwesen nicht nur erkennen, sondern wirklich annehmen. Dazu spricht sich Schiller besonders für einen Vorrang der Empathie vor Grundsätzen der Vernunft und für eine ästhetisch begründete Lebenskunst aus. Mein Essay folgt solchen Denklinien in einer Sequenz der Abschnitte: Die Natur des Menschen – Dauerthema der Wissenschaft. Der Berufsdramatiker als Philosoph - Schillers Briefe zur ästhetischen Erziehung. Gegen den Egoismus der Vernunft, für den Vorrang der Empathie. Grundfähigkeiten des Menschen: Die Natur betrachten, die Natur denken. Segen und Elend der Arbeitsteilung…und Hoffnung auf neue Ganzheit in Formen ästhetischen Lebens. Zurück zur dramatischen Dichtung - Wallensteins brüchiges Verhältnis zur Empathie. Evolution, Empathie und Lebenskunst - „Survival of the fittest“ oder „Survival of the nicest“? Selbstbilder der Seele im Widerspruch - Der falsche Zar Demetrius als Rivale von Boris Godunow. -/- . (shrink)

The full text of this essay is available in an English translation (also in philpapers) under: Alfred Gierer, Science, religion, and basic biological issues that are open to interpretation. Der Artikel bildet das Schlusskapitel des Buches " Alfred Gierer: Wissenschaftliches Denken, das Rätsel Bewusstsein und pro-religiöse Ideen", Königshausen&Neumann, Würzburg 2019. Reichweite und Grenzen naturwissenschaftlicher Erklärungen ergeben sich zum einen aus der universellen Gültigkeit physikalischer Gesetze, zum anderen aus prinzipiellen, intrinsischen Grenzen der Bestimmbarkeit und Berechenbarkeit, zumal bei selbstbezüglichen Fragestellungen. In diesem (...) Essay geht es um deutungsoffene Grundfragen in Zusammenhang mit der Beziehung von Wissenschaft und Religion: Der Unterscheidung von Tier und Mensch, der Entstehung der mentalen Fähigkeiten der biologischen Spezies „Mensch“, den naturgesetzlichen Voraussetzungen eines „lebensfreundlichen“ physikalischen Universums, und der Reichweite wie den Grenzen einer naturwissenschaftlichen Erklärung von menschlichem Bewusstsein. Naturwissenschaft kann auf der philosophischen, kulturellen und religiösen Ebene die Mehrdeutigkeit der Welt nicht auflösen. Agnostische und religiöse Grundauffassungen werden auf Dauer ko-existieren, und die Wahl ist nicht nur eine Frage des Wissens, sondern besonders auch der Weisheit und der Lebenskunst. (shrink)

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. (shrink)

Unsere Kulturfähigkeit ist ein Ergebnis der biologischen Evolution der Spezies “Mensch”; die einzelne Kultur selbst jedoch ist ein Produkt gesellschaftlicher Entwicklungen, Differenzierungen und Traditionen. Der Kulturvergleich zeigt uns erhebliche Spielräume für Ausprägungen von Gemeinsinn. Da dessen Aktivierung wesentlich zur Lebensqualität einer Gesellschaft beiträgt, sind Versuche einer realistischen Einschätzung kultureller Gestaltungsspielräume in dieser Hinsicht sinnvoll. Sie sind nicht zuletzt durch die biologischen Grund- und Randbedingungen der Spezies Mensch gegeben und begrenzt, zumal hinsichtlich von Anlagen zu altruistischem und kooperativem Verhalten. Während bis (...) vor kurzem Soziobiologen und Sozialwissenschaftler oft wenig Neigung zu gegenseitigem Verständnis zeigten, zumal manche Biologen relativ extreme Theorien über genetisch angelegte egoistische Verhaltensanlagen vertraten, verstehen sich neuere, durch die Spieltheorie beeinflusste und sehr allgemeine psychische Disposition betonende Linien soziobiologischen Denkens dazu, auch ausgesprochen freundliche Eigenschaften unserer Spezies zu erklären und zu begründen. Sie kommen sozialwissenschaftlichen Bestrebungen entgegen, zum Beispiel in Zusammenhang mit Theorien begrenzt rationalen Verhaltens, in denen die Fairness eine wesentliche Rolle spielt. Besondere Aufmerksamkeit verdienen in diesem Zusammenhang die biologisch angelegte Fähigkeit zu kognitionsgestützter Empathie sowie die fragile Anlage “Vertrauensbereitschaft”, von denen die Effizienz und das Wohlbefinden in einer Gesellschaft wesentlich abhängen. Insgesamt kann eine - keineswegs unkritische - Beachtung evolutionsbiologischer Aspekte menschlicher Verhaltensdispositionen zu einer realistischen Einschätzung der knappen Ressource “Gemeinsinn” beitragen. Sie ist in Grenzen durchaus ein auch in der Natur des Menschen angelegtes Potential. Dies ist jedoch - unter Beachtung eben dieser Grenzen - behutsam zu aktivieren. Moralische Überforderungen, welche die natürlichen Anlagen des Menschen missachten, sind kontraproduktiv. (shrink)

• 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. (shrink)

The development of modern science has depended strongly on specific features of the cultures involved; however, its results are widely and trans-culturally accepted and applied. The science and technology of electricity provides a particularly interesting example. It emerged as a specific product of post-Renaissance Europe, rooted in the Greek philosophical tradition that encourages explanations of nature in theoretical terms. It did not evolve in China presumably because such encouragement was missing. The trans-cultural acceptance of modern science and technology is postulated (...) to be due, in part, to the common biological dispositions underlying human cognition, with generalizable capabilities of abstract, symbolic and strategic thought. These faculties of the human mind are main prerequisites for dynamic cultural development and differentiation. They appear to have evolved up to a stage of hunters and gatherers perhaps some 100 000 years ago. However, the extent of the correspondence between some constructions of the human mind and the order of nature, as revealed by science, is a late insight of the last centuries. Quantum physics and relativity are particularly impressive examples. (shrink)

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. (shrink)

Full applicability of physics to human biology does not necessarily imply that one can uncover a comprehensive, algorithmic correlation between physical brain states and corresponding mental states. The argument takes into account that information processing is finite in principle in a finite world. Presumbly the brain-mind-relation cannot be resolved in all essential aspects, particularly when high degrees of abstraction or self-analytical processes are involved. Our conjecture plausibly unifies the universal validity of physics and a logical limitation of human thought, and (...) it does not regard consciousness -the most basic human experience - as a marginal phenomenon. (shrink)

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. -/- -/- . (shrink)

The layers of a solvent liquid flowing around a moving molecule have a finite thickness corresponding to the finite dimensions of the solvent molecules. Taking this feature into account leads to a modification of Stokes’ laws of the relation between friction and viscosity in continuous media. We derive the observed order of magnitude of the microfriction, for rotation as well as translation, and its approximately correct dependence on the radii of moving and solvent molecules.

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. (shrink)

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. (shrink)

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. (shrink)

Cells isolated from this freshwater polyp can aggregate and form a complete new animal. Experiments with the system lend support to a physico-chemical scheme for the creation of biological pattern.

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. (shrink)

Nikolaus von Kues ist eine der faszinierendsten Persönlichkeiten im Übergang vom Mittelalter zur Neuzeit. Während seine theologischen und neuplatonischen Vorstellungen viel beachtet werden, gilt das weniger für seine naturphilosophischen Ideen: Wie Gott die Welt in Wirklichkeit, so schafft der Mensch sie in Gedanken. Beobachtung, Experiment und Mathematik sind zum Verständnis der Natur notwendig. Die biblische Überlieferung ist nicht wörtlich zu nehmen. Er propagierte ein fast unendliches Universum ohne Mittelpunkt und Begrenzung mit einer sich bewegenden Erde. Besonders bedeutsam im Hinblick auf (...) Reichweite und Grenzen moderner Naturwissenschaft ist seine Theorie des "Wissens vom Nichtwissen": Wissenschaft selbst ist geeignet, ihre eigenen Grenzen zu erkennen. Die Schrift würdigt auch die Persönlichkeit des Cusanus und schließt mit einem Essay über die Beziehung von Naturwissenschaft und Religion in unserer Zeit. The booklet is a re-edition of sections on Nicolas de Cusa in my book "Die gedachte Natur" (1991), also in philpapers. Cusanus was of one of the most original philosophers of the early Renaissance. He gave reasons for human self-confidence: as God created the world order in reality, man creates it in his mind. Not only mathematics, but also quantitative experiments, are essential for understanding nature. Human rationality is superior to verbal interpretations of the Bible: the universe is almost infinite, with no limits and no centre, and with a moving earth. And he insisted on what he considered to be the highest form of knowledge: the knowledge of the limits of knowledge, with far-reaching implications for the philosophy of nature and human cognition. (shrink)

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). -/- . (shrink)

This book (in German) on "Physics, life and mind" is on the physical foundations of modern biology. The basic features of living systems, reproduction, mutation and metabolism, can be explained in terms of molecular processes involving nucleic acids as genetic material, and proteins as catalysts. The generation of structure and form in each generation results from spatiotemporal gene regulation in conjunction with the de novo formation of spatial order in which interplays of activation and inhibition play a crucial part. Brain (...) functions can be understood in terms of information processing in neural networks. Fundamental limitations of explanations of biological phenomena on the basis of physics are expected for the relation between neural and mental states, which may not be fully decodable by finite procedures. A complete algorithmic theory of the human mind encompassing all, including self-referential, aspects appears to be impossible even in principle, not only in practice. The range and limitations of explanations of life on the basis of physical laws and processes reflect the scope and limits of science in general. In contrast to the notions in circulation in the 19th century, modern science is open at the metatheoretical level to different philosophical, cultural and religious interpretations of man and the universe. -/- . (shrink)

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 theological 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. -/- This article in English is based on the monography (in German): A. Gierer “Eriugena, al-Kindi, Nikolaus von Kues - Protagonisten einer wissenschaftsfreundlichen Wende im philosophischen und theologischen Denken”, Acta Historica Leopoldina 29 (1999), Barth Verlag in MVH Verlage Heidelberg, ISBN: 3-335-00652-6, which is also available online on this server. -/- -/- . (shrink)

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. (shrink)

This is an English translation of my essay: Alfred Gierer Wissenschaft, Religion und die deutungsoffenen Grundfragen der Biologie. Mpi for the History of Science, preprint 388, 1-21, also in philpapers. Range and limits of science are given by the universal validity of physical laws, and by intrinsic limitations, especially in self-referential contexts. In particular, neurobiology should not be expected to provide a full understanding of consciousness and the mind. Science cannot provide, by itself, an unambiguous interpretation of the natural order (...) at the philosophical, cultural and religious level. The diversity of interpretations, however appears as a positive factor of cultural dynamics. Historically, the revival of the philosophy of nature in the middle ages included remarkable biological thoughts such as those of Eriugena and Thierry of Chartres. In this essay, emphasis is placed on basic issues of modern biology – the distinction of man and animal, the evolution of human mental capabilities, the physics of the universe as precondition for biological evolution, and the intricasies of the brain-mind-relation. They are open to agnostic as well as religious interpretations, the individual choice being mainly a matter of wisdom and not just of knowledge. -/-. (shrink)

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. -/- . (shrink)

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. (shrink)

Georg Ernst Stahl (1659-1734) was a German physician and chemist. The book (in German) documents a symposium of the Academy Leopoldina on his works and thoughts that contributed to the Enlightenment. Der weite Horizont seines Denkens und seiner Arbeiten umfasst die Phlogiston-Theorie der Verbrennung, die später mit der Entdeckung des Sauerstoffs widerlegt wurde, aber dennoch wichtige Erkenntnisse zur Reversibilität von Reaktionen und zur unsichtbaren Persistenz der beteiligten chemischen Komponenten beitrug. Seine Gedanken zur Rolle der „Anima“, die heute überholt erscheinen, führten (...) bereits am Beginn des 18. Jahrhunderts Konzepte ein, die für die moderne Biologie und Psychologie von Bedeutung sind. Dazu zählen etwa Homöostase, Synergie, die Vorbereitung willentlicher Bewegungen und Unterschiede zwischen unbewussten aber vernünftigen Handlungen und solchen, die von rationalen Erwägungen geleitet werden. Stahls medizinisches Hauptwerk ist die „Theoria medica vera”, Halle 1708. Eine der zentralen Publikationen zur chemischen Theorie der Verbrennung ist die „Zymotechnia fundamentalis seu fermentationis theoria generalis”, Halle 1697, in deutscher Sprache 1734. Siehe auch „Georg Ernst Stahl (1659-1734), German Physician and Chemist“, Artikel von A. Gierer, in: Encyclopedia of the Enlightenment (Hg. A.C. Kors), Bd. 4, Oxford University Press, New York 2003, S. 124-125. -/- . (shrink)