Gradualism
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Gradualism is a concept in evolutionary theory. It has two different meanings. In the context of the rate of evolution, gradualism means that the rate of evolution is constant (phyletic gradualism). In the context of evolution of adaptations, gradualism means that adaptations form over many intermediate steps and do not appear erratic.
Phyletic gradualism is when the rate of evolution is constant. If the rate of evolution within a species is slower than the rate of emergence of new species, this is instead referred to as punctualism. While Darwinian evolutionary theory does not rely on phyletic gradualism, gradualism is an alternate in the context of evolution of adaptations.
Darwin always emphasized that evolution is slow and gradual. Stephen Jay Gould concluded that Darwin meant phyletic gradualism, and that the theory of punctualism thus contradicted Darwinism and neo-Darwinism. According to Richard Dawkins, Darwin was not referring to evolutionary rate and speciation. Darwin's remarks in the latter context were perfectly compatible with punctualism:
"Many species, when formed, never undergo further changes (...) and the periods during which the species have been subject to modification, though long when measured by years, have probably been but short in proportion to those during which they have remained unchanged."
- Charles Darwin: The Origin of Species. S. 551
Darwin and all subsequent versions of Darwinism have been gradualist about the evolution of adaptations, but not about the rate of evolution. The only condition that evolutionary theory places on the rate of evolution is that fossils must not evolve faster than the fastest experimentally demonstrated rates of evolution based on normal genetic variation. If this condition were not met, it would be a serious challenge to neo-Darwinism. However, all fossil evolution rates known to date are slower than those from genetic experiments.
Gradualism, above
Questions and Answers
Q: What is gradualism?
A: Gradualism is the process of change happening by gradual and slow stages.
Q: What is the opposite of gradualism?
A: The opposite of gradualism is rapid change and revolution.
Q: With which political philosophy is gradualism sometimes associated?
A: Gradualism is sometimes associated with social democracy in politics.
Q: Which geological concept is in line with gradualism?
A: Uniformitarianism is in line with gradualism in geology.
Q: Which idea of species change is in tune with gradualism?
A: Darwinian idea of slowly changing species is in tune with gradualism in biology.
Q: Define catastrophism.
A: Catastrophism is a geological concept that states sudden and significant changes occur in Earth's history due to natural disasters.
Q: How is gradualism different from catastrophism in geology?
A: Gradualism in geology is the idea that changes occur slowly whereas catastrophism is the idea that significant and instant changes can happen due to natural disasters.
