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Dollo’s Law Tuesday, May 29, 2007

Posted by henry000 in anti-creationism, biology, Dawkins, Dollo's Law, evolution, genetics, Richard Dawkins, science, sea snails, Stephen Gould.
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Dollo’s law is one interesting hypothesis in the theory of evolution. In its original form, it states that evolution is irreversible – that is, once an organism has lost or discarded a structural feature during the course of evolution, then it cannot regain that feature.

This law was proposed firstly in 1890 by a biologist named Louis Dollo. In its modern form, this law should be understood as one that hypothesises that evolution is highly unlikely reversible – that is, it is highly improbable that an organism would regain a lost feature.

This law kind of makes sense under the first impression – life evolves from simple to complex, and it seems that there is no known case of organisms regrowing a previously discarded feature. However, on a second thought, one must pause and examine the issue further. None of the evolution mechanisms – natural selection, sexual selection, genetic drift, genetic mutation, genetic recombination, symbiogenesis and so on – dictates that organisms cannot completely regain lost features. In fact, scientists have argued that at least theoretically there is no block to evolutionary reversion.