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GLP Science Superthread : 2012, DNA, Neutrinos, Solar Anomalies, Signal from Galactic Center and MORE
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A compilation of documented science for people wanting more than a GLPers personal opinion on the state of where we are and where we could be headed as a planet/human species.
PUNCTUADED EQUILIBRIUM
--"instead of a slow, continuous movement, evolution tends to be characterized by long periods of virtual standstill ("equilibrium"), "punctuated" by episodes of very fast development of new forms.
The "punctuated equilibrium" theory of Niles Eldredge and Stephen Jay Gould was proposed as a criticism of the traditional Darwinian theory of evolution. Eldredge and Gould observed that evolution tends to happen in fits and starts, sometimes moving very fast, sometimes moving very slowly or not at all. On the other hand, typical variations tend to be small. Therefore, Darwin saw evolution as a slow, continuous process, without sudden jumps. However, if you study the fossils of organisms found in subsequent geological layers, you will see long intervals in which nothing changed ("equilibrium"), "punctuated" by short, revolutionary transitions, in which species became extinct and replaced by wholly new forms. Instead of a slow, continous progression, the evolution of life on Earth seems more like the life of a soldier: long periods of boredom interrupted by rare moments of terror.
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.
A fundamental example of such a major change is the metasystem transition, where a system evolves in a relatively short time to a higher level of complexity.
[link to pespmc1.vub.ac.be]
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