Philosophy Dictionary of ArgumentsHome
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| Life: Life is the state of being characterized by growth, metabolism, homeostasis, adaptation, reproduction, and response to stimuli. Living organisms are made up of cells, which are the basic units of life._____________Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments. | |||
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Stephen Jay Gould on Life - Dictionary of Arguments
I 227 ff Beginning/life/Gould: e.g. at the end of 1977, fossil prokaryotes were discovered in South Africa, which were about 3.4 billion years old. This is a much earlier beginning of life than previously assumed. Definition prokaryotes: prokaryotes are e.g. bacteria and blue-green algae, among others and they form the kingdom of the Definition Monera: Monera have no organelles, no nuclei, no mitochondria. A short time later it was announced that these methane bacteria are not closely related to other Monera at all. Common ancestors had to be much older! The oldest dated rocks in West Greenland are 3.8 billion years old. So there is very little time from the creation of decent living conditions to the creation of life itself. Perhaps the emergence of life (primitive life) is as inevitable as that of feldspar or quartz. If methanogens are listed separately, they form a sixth kingdom. Biologists today distinguish between Eukaryotes and prokaryotes rather than between plants and animals. Because of a common RNA sequence, the prokaryotes must have had a common precursor at some point in time. I 234 The assumption of a steady evolutionary speed is probably impossible to maintain. The early methanogens may have developed much faster. I 260 Form/life/organism/evolution/physics/Gould: stability is created by the fact that a living being is large enough to penetrate into an area where gravity surpasses the forces that take place on the surface. As the ratio of surface to volume decreases with growth, an increasing size is the safest way into this area. The Earth's physical environment contains numerous habitats, which are only available to organisms that are larger than single-celled organisms. The multicellularity probably originated in several places independently of each other. It has the two main features of analogue similarity: 1. it is relatively easy to reach and both highly adaptable and flexible and 2. it is the only possible route to the benefits it brings. With the exception of ostrich eggs, individual cells cannot grow very large. I 261 The multicellularity has probably arisen even within the individual kingdoms several times. Most biologists believe that it occurs in plants and fungi through amalgamation. These organisms are the descendants of protist colonies. (Protists: protists are unicellular organisms, see Terminology/Gould) For example, some Volvox colonies with a fixed number of cells are regularly arranged. The cells may differ in size and the reproductive function may be limited to those of them located at a pole. I 264 Larger animals have such a low ratio of outer surface to volume that they need to form internal organs to increase the available surface area. I 288 Ratio of surface to volume: the ratio of surface to volume is very high in small organisms. Heat is generated by the volume of the body and radiated at its surface. Therefore warm-blooded animals have a particularly high energy requirement. Field mice must eat all the time. The ratio was so low for the large dinosaurs that they could get by without an insulation layer. I 311 Shape/life/physics/size/Gould: the character of Morgan in E. L. Doctorow's "Ragtime" was wrong when he thought that large mammals were geometric copies of their smaller relatives. Elephants have relatively larger brains and thicker legs than mice. He is right in that larger animals are often similar to smaller relatives in the same group. Galileo already gave a classic example: the strength of a leg is a function of the cross-section. The weight that the legs have to carry varies with their volume. In order for the bodily functions to remain the same, animals must change their form when they become larger: "scaling theory". E. g. from crab spider to tarantula, the scale of relatives reaches up to a thousand times the body weight of the smallest specimen. Here too, the scale runs regularly: the duration of the heartbeat increases only 4/10 times as fast as the body weight. I 312 Small animals move through life much faster than large ones, their heart beats faster, they breathe more frequently, their pulse is faster, their "fire of life "burns" faster: in mammals, the metabolic rate increases by only three quarters as fast as the body weight. Smaller ones tend to live shorter than large ones. I 313 However, the homo sapiens lives much longer than a comparable mammal of the same size: See Neoteny/Gould. The importance of the astronomical time is by no means to be denied; animals must measure it in order to survive. I 315 Breathing time and heartbeat increase about 0.28 times faster than body weight; the body weight can be reduced, leaving mammals of any size to breathe once at about 4 beats. For all mammals, regardless of their size, they also breathe about 200 million times during their lifetime, the heart beats about 800 million times. I 318 ff There are magnetotactic bacteria that orient themselves according to the fields and move accordingly. They thus resist the mechanism of Brownian movement. It was discovered that the magnets are distributed in the body of the bacteria in the form of about 20 small particles. Question: why is there this distribution of magnetism on particles, and why are these particles about 500 Angstrom large (1 Angstrom = 1 ten millionth of a millimetre). They form a chain in the body of the elongated bacteria. I 320 If these particles were a little smaller (about one-fifth smaller) then they would be "superparamagnetic", i. e. a magnetic reorientation of the particles could be effected at room temperature. If, on the other hand, they were twice as large, for example, the particles would form their own magnetic range within the particles, pointing in different directions. What can such a small creature do with a magnetic field? The room for movement during the few minutes of their existence is probably only a few centimetres. It does not really matter which way it goes. It can now be decisive for a bacterium to move downwards. Now gravity can be felt at least as well without a magnetic field. However, this only applies to large organisms. I 322 Insects and birds live in a world dominated by forces that affect the surface. Some of them can run on water or hang down from the ceiling because the surface tension is so strong and the gravitation is relatively weak. Gravity is hardly a problem for insects and for bacteria not at all. - - - II 325 Life/sense/Gould: thesis: the history of life has some weak empirical tendencies, but in essence it is nowhere to be found. - - - IV 196 Life/multicellular organisms: life only existed for 600 million years. This time is divided into three major parts: Palaeozoic (old earth age), Mesozoic (earth middle age) and Cenozoic (modern earth age). All problematic cases take place in the Palaeozoic. Surprisingly, there is a superordinate pattern: although the number of problematica (organisms that had no future in evolution and therefore, due to their rarity and isolation are difficult to allocate) is declining towards the modern age, it is amazing how they almost completely disappear towards the end of the Palaeozoic. In the early history of multicellular organisms, the problematica must have flourished. IV 303 Life/Gould: life as a result of structural and functional complexity cannot be broken down into its chemical components and cannot be explained in its entirety by laws. Function: e.g. the cell membrane controls many processes in the cell. How can we interpret the functions of cells by breaking them down into molecular components? - - - III 207 Life/development/complexity: Gould: 7 arguments 1. Life must begin on the left wall (minimum complexity). 2. There must be temporal stability of the original bacterial form. The prokaryotes (organisms without nucleus, chromosomes, mitochondria and choroplasts) consist of breathtakingly diverse groups, which are collectively called "bacteria" and the "blue-green algae", also called bacteria (cyanobacteria), which make use of the photosynthesis. More than half the history of life is the history of prokaryotes. 3. In order for life to spread, a more and more right-wing distribution had to develop. 4. Characterizing a total distribution by an extreme value in a tail is short-sighted. More than 80% of all species are arthropods, and as a rule all members of this tribe are considered primitive. Moreover, the forms that occupied the right tail over time do not form an uninterrupted evolutionary sequence. It is a colorful row that is not connected. Time Sequence: bacteria, eukaryotic cell, marine algae, jellyfish, trilobite, nautilus, shellfish, dinosaurs, sabre-toothed tigers, homo sapiens. 5. Causality lies on the ((s) left) wall (lowest complexity) and in the extension of the range of variations. The right tail is not cause, but effect. III 212 6. The only way to reintroduce progress is logically possible, but empirically most likely wrong. The first living creature stands on the left wall but the first mammal, the first flowering plant or the first clam starts from the middle and the offspring can move in both directions. But there are good reasons to assume a preference for the direction to the left, because parasitism is a very common evolutionary strategy, and parasites are anatomically usually built simpler than their independent ancestors (Vs progress!). So the whole system could contain subordinate counterlines. Empirically, the finds show no preference to the right! 7. Even a narrow-minded limitation to the right tail (>complexity) does not lead to the desired conclusion, namely a predictable, meaningful evolution to the supremacy of a conscious being. The right tail must exist statistically, but what kind of living things exist cannot be predicted at all. It is by no means determined by the mechanisms of evolution! If evolution were to repeat itself, the development to human-like beings would be virtually impossible, because of the extreme improbability._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. Translations: Dictionary of Arguments The note [Concept/Author], [Author1]Vs[Author2] or [Author]Vs[term] resp. "problem:"/"solution:", "old:"/"new:" and "thesis:" is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition. |
Gould I Stephen Jay Gould The Panda’s Thumb. More Reflections in Natural History, New York 1980 German Edition: Der Daumen des Panda Frankfurt 2009 Gould II Stephen Jay Gould Hen’s Teeth and Horse’s Toes. Further Reflections in Natural History, New York 1983 German Edition: Wie das Zebra zu seinen Streifen kommt Frankfurt 1991 Gould III Stephen Jay Gould Full House. The Spread of Excellence from Plato to Darwin, New York 1996 German Edition: Illusion Fortschritt Frankfurt 2004 Gould IV Stephen Jay Gould The Flamingo’s Smile. Reflections in Natural History, New York 1985 German Edition: Das Lächeln des Flamingos Basel 1989 |
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Ed. Martin Schulz, access date 2024-04-27