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Discussion and Debate
Discussion and Debate
Physical & Life Sciences
Creation & Evolution
At what point does it become dishonest?
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<blockquote data-quote="ChordatesLegacy" data-source="post: 49011710" data-attributes="member: 193033"><p><strong><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">This seems to be Kindergarten level; so there&#8217;s every chance you will understand it.</span></span></strong></p><p> </p><p><a href="http://pespmc1.vub.ac.be/Punctueq.html" target="_blank"><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">LINK TO TEXT</span></span></a></p><p> </p><p><em><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">Punctuated equilibrium is more an observation than a theory of evolution. However, this observation is easy to explain by using some general insights from the systems approach. Consider a typical </span></span><a href="http://pespmc1.vub.ac.be/FITLANDS.html" target="_blank"><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">fitness landscape</span></span></a><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">, in which there are valleys separated by ridges. If the evolving system has reached the bottom of a deep valley, there will be almost no change, since variation will fail to pull the system out of that hole. This is a negative </span></span><a href="http://pespmc1.vub.ac.be/FEEDBACK.html" target="_blank"><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">feedback</span></span></a><span style="font-size: 12px"><span style="font-family: 'Times New Roman'"> regime, in which chance fluctuations will be counteracted, pulling the system back to its equilibrium position at the bottom of the valley. </span></span></em></p><p><em><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">On the other hand, if there is only a small ridge separating the valley from a neighboring, deeper valley, then a chance event may be sufficient to push the system over the edge so that it enters the other valley. Such a lucky variation will become increasingly likely when the fitness landscape changes so as to reduce the height of the ridge. Once over the ridge, the descent into the new valley will go very fast. This is a positive feedback regime in which deviations from the previous position are amplified. This means that the system will evolve very quickly to a new, fitter configuration. If we would check the evolution of the species in the geological record, we would find many fossils corresponding to the position at the bottom of the valley where the organism remained for so long, but few or none corresponding to the crossing of the ridge, which happened very fast on the geological time scale. </span></span></em></p><p><em><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">The systems approach can help us to understand more profoundly how a small variation can produce a major change. Indeed, organisms, like all systems, are organized in levels, corresponding to their subsystems and subsubsystems. Each subsystem is described by its own set of genes. A mutation in one of the components at the lower levels will in general have little effect on the whole. On the other hand, a mutation at the highest level, where the overall arrangement of the organism is determined, may have a spectacular impact. For example, a single mutation may turn a four-legged animal into a six-legged one. Such high-level mutations are unlikely to be selected, but potentially they can lead to revolutionary changes. </span></span></em></p><p><em><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">A fundamental example of such a major change is the </span></span><a href="http://pespmc1.vub.ac.be/MST.html" target="_blank"><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">metasystem transition</span></span></a><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">, where a system evolves in a relatively short time to a higher level of complexity. </span></span></em></p><p></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'"><strong>Reference:</strong> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Gould S.J., and N. Eldredge. 1977: Punctuated equilibria: the tempo and mode of evolution reconsidered. Paleobiology 3, pp. 115-151.</span></span></p></blockquote><p></p>
[QUOTE="ChordatesLegacy, post: 49011710, member: 193033"] [B][SIZE=3][FONT=Times New Roman]This seems to be Kindergarten level; so there’s every chance you will understand it.[/FONT][/SIZE][/B] [B][FONT=Times New Roman][SIZE=3][/SIZE][/FONT][/B] [URL="http://pespmc1.vub.ac.be/Punctueq.html"][FONT=Times New Roman][SIZE=3]LINK TO TEXT[/SIZE][/FONT][/URL] [I][FONT=Times New Roman][SIZE=3]Punctuated equilibrium is more an observation than a theory of evolution. However, this observation is easy to explain by using some general insights from the systems approach. Consider a typical [/SIZE][/FONT][URL="http://pespmc1.vub.ac.be/FITLANDS.html"][FONT=Times New Roman][SIZE=3]fitness landscape[/SIZE][/FONT][/URL][FONT=Times New Roman][SIZE=3], in which there are valleys separated by ridges. If the evolving system has reached the bottom of a deep valley, there will be almost no change, since variation will fail to pull the system out of that hole. This is a negative [/SIZE][/FONT][URL="http://pespmc1.vub.ac.be/FEEDBACK.html"][FONT=Times New Roman][SIZE=3]feedback[/SIZE][/FONT][/URL][SIZE=3][FONT=Times New Roman] regime, in which chance fluctuations will be counteracted, pulling the system back to its equilibrium position at the bottom of the valley. [/FONT][/SIZE][/I] [I][SIZE=3][FONT=Times New Roman]On the other hand, if there is only a small ridge separating the valley from a neighboring, deeper valley, then a chance event may be sufficient to push the system over the edge so that it enters the other valley. Such a lucky variation will become increasingly likely when the fitness landscape changes so as to reduce the height of the ridge. Once over the ridge, the descent into the new valley will go very fast. This is a positive feedback regime in which deviations from the previous position are amplified. This means that the system will evolve very quickly to a new, fitter configuration. If we would check the evolution of the species in the geological record, we would find many fossils corresponding to the position at the bottom of the valley where the organism remained for so long, but few or none corresponding to the crossing of the ridge, which happened very fast on the geological time scale. [/FONT][/SIZE][/I] [I][SIZE=3][FONT=Times New Roman]The systems approach can help us to understand more profoundly how a small variation can produce a major change. Indeed, organisms, like all systems, are organized in levels, corresponding to their subsystems and subsubsystems. Each subsystem is described by its own set of genes. A mutation in one of the components at the lower levels will in general have little effect on the whole. On the other hand, a mutation at the highest level, where the overall arrangement of the organism is determined, may have a spectacular impact. For example, a single mutation may turn a four-legged animal into a six-legged one. Such high-level mutations are unlikely to be selected, but potentially they can lead to revolutionary changes. [/FONT][/SIZE][/I] [I][FONT=Times New Roman][SIZE=3]A fundamental example of such a major change is the [/SIZE][/FONT][URL="http://pespmc1.vub.ac.be/MST.html"][FONT=Times New Roman][SIZE=3]metasystem transition[/SIZE][/FONT][/URL][SIZE=3][FONT=Times New Roman], where a system evolves in a relatively short time to a higher level of complexity. [/FONT][/SIZE][/I] [SIZE=3][FONT=Times New Roman][B]Reference:[/B] [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]Gould S.J., and N. Eldredge. 1977: Punctuated equilibria: the tempo and mode of evolution reconsidered. Paleobiology 3, pp. 115-151.[/FONT][/SIZE] [/QUOTE]
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