- Dollo's law
Dollo's Law or Dollo's Principle is a
hypothesis proposed by French-born Belgian paleontologistLouis Dollo (1857-1931) in 1890 that states thatevolution is not reversible. This law was first stated by Dollo in this way: "Anorganism is unable to return, even partially, to a previous stage already realized in the ranks of itsancestor s." [Dollo, quoted in "Evolution: Ammonites Indicate Reversal," in "Nature",March 21 ,1970 ] . According to this hypothesis a structure or organ that has been lost or discarded through the process of evolution will not reappear in that line of organisms.According to
Richard Dawkins , the law is "really just a statement about the statistical improbability of following exactly the same evolutionary trajectory twice (or, indeed, any particular trajectory), in either direction." [cite book | first = Richard | last = Dawkins | authorlink = Richard Dawkins | title = The Blind Watchmaker | publisher = W. W. Norton & Company, Inc. | location = New York | origyear = 1986 | year = 1996 | id = ISBN 0-393-31570-3 ]Stephen Gould viewed the idea less strictly, suggesting that "irreversibility " forecloses certain evolutionary pathways once broad forms have emerged: " [For example] , once you adopt the ordinary body plan of areptile , hundreds of options are forever closed, and future possibilities must unfold within the limits of inherited design." [Gould, Stephen J. [1993] (2007) "Eight little piggies," Vintage Books. ISBN 978-0-099-50744-4]ee also
*
Entropy and life
*Irreversibility References
External links
* [http://www.corante.com/loom/archives/000796.html The Loom: Recoil From Dollo's Law]
* [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=45421 Dollo's Law and the Death and Resurrection of Genes]
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