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- Pierre Louis Maupertuis


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Pierre Louis Moreau de Maupertuis (* 7. Juli 1698, Saint-Malo; † 27. Juli 1759, Basel) war ein französischer Mathematiker, Astronom und Philosoph, der das Prinzip der kleinsten Wirkung entdeckte.

Leben 

Im Alter von 20 Jahren trat Maupertuis als Kavallerie-Hauptmann in die Armee ein und diente dort fünf Jahre lang. In seiner freien Zeit studierte er Mathematik und machte dabei Bekanntschaft mit Newtons Gravitationstheorie. Im Gegensatz zu den Bernoullis wurde er zu einem heftigen Befürworter dieser Theorie – was damals noch einigen Mut erforderte und neben naturwissenschaftlichen auch philosophische Fragen aufwarf.

1723 wurde er 25jährig in die französische Akademie der Wissenschaften aufgenommen. 1728 besuchte er London und wurde zu einem Mitglied der Royal Society gewählt.

1736 führt er eine Expedition im Auftrag König Ludwig XV. nach Lappland, um dort die Länge eines Breitengrades zu vermessen. Zeitgleich mit einer zweiten Gruppe in Peru (Pierre Bouguer, Charles Marie de La Condamine, Louis Godin) sollte dabei eine genaue Gradmessung vorgenommen werden, um aus den Unterschieden im Krümmungsradius der Erde ihre Größe und Form zu bestimmen. Auf seine wissenschaftliche Leistung unter den schwierigen Verhältnissen war Maupertuis so stolz, dass er oft die Tracht der Lappen trug.

1740 lud ihn Friedrich der Große auf Empfehlung von Voltaire nach Berlin ein, um ihm die Leitung der Preußischen Akademie der Wissenschaften zu übertragen. Da Friedrich jedoch mit militärischen Fragen beschäftigt war, begleitete Maupertuis ihn und geriet während der Schlacht bei Mollwitz in österreichische Gefangenschaft, wurde nach Wien gebracht, dort allerdings freundlich behandelt und bald durch Maria Theresia freigelassen. Er kehrte zunächst nach Berlin, schon im Juni 1741 aber nach Paris zurück, um das Ende des 2. Schlesischen Kriegs abzuwarten.

Er wurde zunächst stellvertretender Leiter der Académie des Sciences, im Jahr darauf ihr Leiter. Am 27. Juni 1743 wurde er in die Académie française aufgenommen. Im Herbst 1744 reiste Maupertuis nach Basel, dann wieder nach Berlin, wo er von Friedrich bedrängt wurde, seine Akademie zu leiten. Dort heiratete er am 25. August 1745 Eleonore von Borck, eine Verwandte des Staatskanzlers.

Am 12. Mai 1746 wurde Maupertuis offiziell zum Präsidenten der Berliner Akademie ernannt, geriet aber bald in verschiedene Querelen, unter anderem weil er kaum Deutsch konnte. Eine der Querelen wurde ausgelöst von Johann Samuel König, der Maupertius' Werk über Lappland übersetzt hatte und ihm vorwarf, das von ihm formulierte „Prinzip der kleinsten Wirkung“ stamme von Leibniz. Als der Akademiepräsident dies ungeschickt bestritt, wurde er von Voltaire mit dem anonym veröffentlichten Pamphlet Diatribe du Docteur Akakia attackiert. Obwohl Friedrich II. zu Maupertuis hielt, nahm dieser 1753 seinen Abschied (Nachfolger wurde Jean-Baptiste de Boyer, Marquis d'Argens (1704–1771) und zog 1756 nach Basel. Dort starb er 1759 im Haus von Johann Bernoulli II..

Auf Friedrichs Reiterdenkmal von 1751 ist Maupertuis als bedeutender Wissenschafter erwähnt, dem die Organisation der preußischen Akademie zur Zufriedenheit des Herrschers gelang.

Sein schwieriger Charakter, der u. A. auf seine Erziehung und die Verwöhnung durch seine Mutter zurückgeführt wird, die ihren Sohn weniger geliebt als vergöttert haben soll, führte während seines Lebens zu zahlreichen Auseinandersetzungen.


Arbeiten über Biologie

Maupertuis war nicht nur ein Mathematiker und guter Kenner der Theorien Newtons und Leibniz', ihm war auch klar, dass die Theorien Newtons nicht ausreichten, um biologische Phänomene zu erklären. Er war in diesem Sinne einer der fortgeschrittensten Denker seiner Zeit, der sich nicht nur gegen den Präformismus und den Newtonschen Determinismus aussprach, sondern auch gegen den Kreationismus. Nach einer Ausstellung eines schwarzen Albinos bildete sich sein Interesse an seinem späterem Lieblingsgebiet: der Vererbung und speziell der Vererbung von Mutationen; er wurde zu einem der Vorväter der modernen Genetik. Für ihn war die Welt zu verschieden und zu heterogen um aus einer geplanten Schöpfung hervorgegangen zu sein.

Man weiß nicht, ob er gläubig war – also an einen Gott glaubte, der nicht etwa direkt in die Vorgänge in der Natur eingriff, sondern an einen Gott der die Naturgesetze erschaffen hatte –, oder ob er Atheist war. Mit seiner eher materialistischen Einstellung, unterstützt durch seine Kenntnisse der Newtonschen Theorien und durch sein Interesse an Vererbungen, entwickelte er eine Theorie der Entstehung des Lebens ähnlich der des Mutationismus von Hugo de Vries. Er nahm an, dass die ersten Lebewesen durch spontane Generation aus zufällig zusammengekommenen toten Materialien, Molekülen oder Keimen entstanden sind; Ideen die schon von antiken Schriftstellern wie Lukrez vertreten wurden. Die Erfindung des Mikroskopes erlaubte die Wahrnehmung kleinster, bis dahin unbekannter Organismen, die die Grenzen zwischen lebender und toter Materie verwischten und Grund zur Annahme der spontanen Erschaffung des Lebens aus zufälligen Kombinationen toter Materie gaben. Lange Zeit glaubte man, dass mikroskopische Organismen, vor allem Aufgusstierchen, aus toter Materie erschaffen werden konnten. Maupertuis nahm an, dass, ausgehend von diesen durch spontane Schöpfung entstandenen Organismen, sich durch starke Mutationen neue Spezies entwickelten. Durch diese Mutationen und durch Kreuzungen zwischen den Spezies würde sich im Laufe der Zeit die heute beobachtbare große Diversität der Spezies erklären. Ähnlich erklärte er die Eliminierung von mangelhaften Mutationen.

Maupertuis war Essentialist in dem Sinne, dass er jede Spezies, die sich von ihren Nachbarn unterschied, auf die taxonomische Landkarte setzte. Auch wenn er die Schaffung neuer Wesenszüge annahm, konnte er sich jedoch nicht eine graduelle Anpassung der Spezies durch die Selektion der am besten angepassten Mitglieder dieser Spezies vorstellen.


Schriften

Seine wichtigsten Arbeiten beinhalten:


Siehe auch


Weblinks 



Quelle (05.2008):  http://de.wikipedia.org/wiki/Pierre_Louis_Maupertuis








Pierre-Louis Moreau de Maupertuis (July 17, 1698July 27, 1759) was a French mathematician, philosopher and man of letters. He is often credited with having invented the principle of least action.

Biography

Maupertuis was born at Saint-Malo, France, to a moderately wealthy family of merchant-corsairs[citation needed]. He was educated in mathematics by a private tutor, and upon completing his formal education his father secured him a largely honorific cavalry commission. After three years in the cavalry, during which time he became acquainted with fashionable social and mathematical circles, he moved to Paris and began building his reputation as a mathematician and literary wit. In 1723 he was admitted to the Académie des Sciences.




His early mathematical work revolved around the vis viva controversy, for which Maupertuis developed and extended the work of Isaac Newton (whose theories were not yet widely accepted outside England) and argued against the waning Cartesian mechanics. In the 1730s, the shape of the Earth became a flashpoint in the battle among rival systems of mechanics. Maupertuis, based on his exposition of Newton (with the help of his mentor Johan Bernoulli) predicted that the Earth should be oblate, while his rival Jacques Cassini measured it astronomically to be prolate. In 1736 Maupertuis acted as chief of the French Geodesic Mission sent by King Louis XV to Lapland to measure the length of a degree of the meridian. His results, which he published in a book detailing his procedures, essentially settled the controversy in his favor. The book included an adventure narrative of the expedition, and an account of the Käymäjärvi Inscriptions. On his return home he became a member of almost all the scientific societies of Europe.

After the Lapland expedition, Maupertuis set about generalizing his earlier mathematical work, proposing the principle of least action as a metaphysical principle that underlies all the laws of mechanics. He also expanded into the biological realm, anonymously publishing a book that was part popular science, part philosophy, and part erotica: Vénus physique. In that work, Maupertuis proposed a theory of generation (i.e., reproduction) in which organic matter possessed a self-organizing “intelligence” that was analogous to the contemporary chemical concept of affinities, which was widely read and commented upon favorably by Georges-Louis Leclerc, Comte de Buffon. He later developed his views on living things further in a more formal pseudonymous work that explored heredity, collecting evidence that confirmed the contributions of both sexes and treated variations as statistical phenomena.

In 1740 Maupertuis went to Berlin at the invitation of Frederick II of Prussia, and took part in the Battle of Mollwitz, where he was taken prisoner by the Austrians. On his release he returned to Berlin, and thence to Paris, where he was elected director of the Academy of Sciences in 1742, and in the following year was admitted into the Académie française. Returning to Berlin in 1744, again at the desire of Frederick II, he was chosen president of the Prussian Royal Academy of Sciences in 1746, which he controlled with the help of Leonhard Euler until his death. His position became extremely awkward with the outbreak of the Seven Years' War between his home country and his patron's, and his reputation suffered in both Paris and Berlin. Finding his health declining, he retired in 1757 to the south of France, but went in 1758 to Basel, where he died a year later. Maupertuis' difficult disposition involved him in constant quarrels, of which his controversies with Samuel König and Voltaire during the latter part of his life are examples.


Evolution

Some historians of science point to his important works in biology as significant precursors in the development of evolutionary theories, specifically the theory of natural selection. Other writers contend that his remarks are cursory, vague, or incidental to that particular argument. See "Venus Physique" (1745), or its English translation, Boas (1966), for details. Other valuable references include Stephen Jay Gould's The Flamingo's Smile (1987), Desmond King-Hele's Erasmus Darwin (1963), Peter J. Bowler's Evolution: The History of an Idea (1983), and Bentley Glass' Forerunners of Darwin (1959). He also was one of the first to consider animals in terms of variable populations, in opposition to the natural history tradition that emphasized description of individual specimens.

Below is a translation from Vénus Physique, followed by the original French passage:

Could one not say that, in the fortuitous combinations of the productions of nature, as there must be some characterized by a certain relation of fitness which are able to subsist, it is not to be wondered at that this fitness is present in all the species that are currently in existence? Chance, one would say, produced an innumerable multitude of individuals; a small number found themselves constructed in such a manner that the parts of the animal were able to satisfy its needs; in another infinitely greater number, there was neither fitness nor order: all of these latter have perished. Animals lacking a mouth could not live; others lacking reproductive organs could not perpetuate themselves... The species we see today are but the smallest part of what blind destiny has produced...

[1]

Ne pourrait-on pas dire que, dans la combinaison fortuite des productions de la nature, comme il n'y avait que celles où se trouvaient certain rapport de convenance qui puissent subsister, il n'est pas marveilleux que cette convenance se trouve dans toutes les espèces qui existent actuellement? Le hasard, dirait-on, avait produit une multitude innombrable d'individus; un petit nombre se trouvait construit de manière que les parties de l'animal pouvaient satisfaire à ses besoins; dans un autre infiniment plus grand, il n'y avait ni convenance, ni ordre: tous ces derniers ont péri; des animaux sans bouche ne pouvaient pas vivre, d'autres qui manquaient d'organes pour la génération ne pouvaient se perpétuer... les espèces que nous voyons aujourd'hui ne sont que la plus petite partie de ce qu'un destin aveugle avait produit...

A nearly identical argument may be found in Maupertuis' 1746 work Les loix du mouvement et du repos déduites d'un principe metaphysique (its English translation). Desmond King-Hele (1963) points to similar, though not identical, ideas expounded roughly thirty years later by David Hume in his Dialogues Concerning Natural Religion (1777).

The question of who deserves priority for the discovery of the principle of natural selection has long been of particular interest to historians and biologists. Charles Darwin himself, in his foreword to the 6th edition of the Origin of Species, credited Aristotle with foreshadowing the concept of natural selection, and stated that "the first author who in modern times has treated it in a scientific spirit was Buffon". Darwin's fame rests on being the first to develop and publish the concept as a well supported scientific theory, rather than being the first to suggest the concept.

With regard to Maupertuis the question is whether or not Maupertuis had (1) an internally coherent, yet externally robust, theoretical system, (2) an atheistic system or, at a minimum, a non-mystical and thus, scientific system, and/or (3) a broad, overarching theory that tied together all of the available evidence. The chief debate that Maupertuis was engaged in was one that treated the competing theories of generation (i.e. preformationism and epigenesis) indicating that, if Maupertuis was indeed involved in evolutionary speculations, then natural selection may have followed intuitively from clear thinking about the mechanism of biological generation and propagation.

The date of these speculations, 1745, being concurrent with Carolus Linnaeus's own work, predate any firm notion of species, excepting, of course, Aristotle's. Also, the work on genealogy, coupled with the tracing of phenotypic characters through lineages, foreshadows the later work done by Gregor Mendel. The juxtaposition of these subjects suggests that the Modern evolutionary synthesis, while certainly more quantitative, rigorous, and scientific, may have been a rather late addition to a philosophical framework that could already be considered "discovered". In summary, Maupertuis' text is suggestive and deserving of closer scrutiny by scientists and historians, as well as the general public.


Least Action Principle

The principle of least action states that in all natural phenomena a quantity called ‘action’ tends to be minimized. Maupertuis developed such a principle over two decades. For him, action could be expressed mathematically as the product of the mass of the body involved, the distance it had traveled and the velocity at which it was traveling.

In 1741, he gave a paper to the Paris Academy of Sciences, Loi du repos des corps, (Law of bodies at rest). In it he showed that a system of bodies at rest tends to reach a position in which any change would create the smallest possible change in a quantity that he argued could be assimilated to action.

In 1744, in another paper to the Paris Academy, he gave his Accord de plusieurs lois naturelles qui avaient paru jusqu’ici incompatibles (Agreement of several natural laws that had hitherto seemed to be incompatible) to show that the behaviour of light during refraction – when it bends on entering a new medium – was such that the total path it followed, from a point in the first medium to a point in the second, minimised a quantity which he again assimilated to action.

Finally, in 1746 he gave a further paper, the Loix du mouvement et du repos (Laws of movement and rest), this time to the Berlin Academy of Sciences, which showed that point masses also minimise action. Point masses are bodies that can be treated for the purposes of analysis as being a certain amount of matter (a mass) concentrated at a single point. A major debate in the early part of the eighteenth century concerned the behaviour of such bodies in collisions. Cartesian and Newtonian physicists argued that in their collisions, point masses conserved both momentum and relative velocity. Leibnizians, on the other hand, argued that they also conserved what was called live force or vis viva. This was unacceptable for their opponents for two reasons: the first that live force conservation did not apply to so-called ‘hard’ bodies, bodies that were totally incompressible, whereas the other two conservation principles did; the second was that live force was defined by the product of mass and square of velocity. Why did the velocity appear twice in this quantity, as squaring it suggests? The Leibnizians argued this was simple enough: there was a natural tendency in all matter towards motion, so even at rest, there is an inherent velocity in bodies; when they begin to move, there is a second velocity term corresponding to their actual motion.

This was anathema to Cartesians and Newtonians. An inherent tendency towards motion was an ‘occult quality’ of the kind of favoured by mediaeval scholastics and to be resisted at all costs.

Today, of course, the concept of a ‘hard’ body is rejected. And mass times the square of velocity is just twice kinetic energy so modern mechanics reserves a major role for the inheritor quantity of ‘live force’.

For Maupertuis, however, it was important to retain the concept of the hard body. And the beauty of his principle of least action was that it applied just as well to hard and elastic bodies. Since he had shown that the principle also applied to systems of bodies at rest and to light, it seemed that it was truly universal.

The final stage of his argument came when Maupertuis set out to interpret his principle in cosmological terms. ‘Least action’ sounds like an economy principle, roughly equivalent to the idea of economy of effort in daily life. A universal principle of economy of effort would seem to display the working of wisdom in the very construction of the universe. This seems, in Maupertuis’s view, a more powerful argument for the existence of an infinitely wise creator than any other that can be advanced.

He published his thinking on these matters in his Essai de cosmologie (Essay on cosmology) of 1750. He shows that the major arguments advanced to prove God, from the wonders of nature or the apparent regularity of the universe, are all open to objection (what wonder is there in the existence of certain particularly repulsive insects, what regularity is there in the observation that all the planets turn in nearly the same plane – exactly the same plane might have been striking but 'nearly the same plane' is far less convincing). But a universal principle of wisdom provides an undeniable proof of the shaping of the universe by a wise creator.

Hence the principle of least action is not just the culmination of Maupertuis’s work in several areas of physics, he sees it as his most important achievement in philosophy too, giving an incontrovertible proof of God.

The flaws in his reasoning are principally that there is no obvious reason why the product of mass, velocity and time should be particularly viewed as corresponding to action, and even less reason why its minimisation should be an ‘economy’ principle like a minimisation of effort. Indeed, the product of mass, velocity and time is mathematically the equivalent of the integral of live force over time. Leibniz had already shown that this quantity is likely to be either minimised or maximised in natural phenomena. Minimising this quantity could conceivably demonstrate economy, but how could maximising it?


Relation to Kant

Arthur Schopenhauer suggested that Immanuel Kant's "most important and brilliant doctrine" - contained in the Critique of Pure Reason (1781) - was asserted (though not yet "proved") by Maupertuis:

But what are we to say when we find Kant's most important and brilliant doctrine, that of the ideality of space and of the merely phenomenal existence of the corporeal world, expressed already thirty years previously by Maupertuis? ... Maupertuis expresses this paradoxical doctrine so decidedly, and yet without the addition of proof, that it must be supposed that he also obtained it from somewhere else.

The World as Will and Representation, Vol. II, Ch. IV

Main works

His Œuvres were published in 1752 at Dresden and in 1756 at Lyons; books at: http://www.bookmine.org ; http://www.dprix.com/biblio/mpage.html ;


Honors

The Maupertuis crater on the Moon is named after him.


References


See also


Wikimedia Commons has media related to:
Maupertuis


External links

Preceded by
Charles-Irénée Castel de Saint-Pierre
Seat 8
Académie française

1743–1759
Succeeded by
Jean-Jacques Lefranc, marquis de Pompignan




Quelle (05.2008): http://en.wikipedia.org/wiki/Pierre_Louis_Maupertuis




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