Dollo's law of irreversibility

Once an organism has evolved in a certain way, it will not return exactly to a previous form. This is illustrated here in two dimensions; in reality, both biomolecules and organisms evolve in many different dimensions.

Dollo's law of irreversibility (also known as Dollo's law and Dollo's principle), proposed in 1893[1] by Belgian paleontologist Louis Dollo states that, "an organism never returns exactly to a former state, even if it finds itself placed in conditions of existence identical to those in which it has previously lived ... it always keeps some trace of the intermediate stages through which it has passed."[2]

The statement is often misinterpreted as claiming that evolution is not reversible,[3] or that lost structures and organs cannot reappear in the same form by any process of devolution.[4][5] 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".[6] Stephen Jay Gould suggested that irreversibility forecloses certain evolutionary pathways once broad forms have emerged: "[For example], once you adopt the ordinary body plan of a reptile, hundreds of options are forever closed, and future possibilities must unfold within the limits of inherited design."[7]

This principle is classically applied to morphology, particularly of fossils, but may also be used to describe molecular events, such as individual mutations or gene losses.

  1. ^ Dollo, Louis (1893). "Les lois de l'évolution" (PDF). Bull. Soc. Belge Geol. Pal. Hydr. VII: 164–166.
  2. ^ Gould, S. J. (1970). "Dollo on Dollo's law: irreversibility and the status of evolutionary laws". Journal of the History of Biology. 3 (2): 189–212. doi:10.1007/bf00137351. PMID 11609651. S2CID 45642853.
  3. ^ Alfarouk, Khalid O.; Shayoub, Mohammed E.A.; Muddathir, Abdel Khalig; Elhassan, Gamal O.; Bashir, Adil H.H. (22 July 2011). "Evolution of Tumor Metabolism might Reflect Carcinogenesis as a Reverse Evolution process (Dismantling of Multicellularity)". Cancers. 3 (3): 3002–3017. doi:10.3390/cancers3033002. PMC 3759183. PMID 24310356.
  4. ^ Goldberg, Emma E.; Boris Igić (2008). "On phylogenetic tests of irreversible evolution". Evolution. 62 (11): 2727–2741. doi:10.1111/j.1558-5646.2008.00505.x. PMID 18764918. S2CID 30703407.
  5. ^ Collin, Rachel; Maria Pia Miglietta (2008). "Reversing opinions on Dollo's Law". Trends in Ecology & Evolution. 23 (11): 602–609. Bibcode:2008TEcoE..23..602C. doi:10.1016/j.tree.2008.06.013. PMID 18814933.
  6. ^ Dawkins, Richard (1996) [1986]. The Blind Watchmaker. W. W. Norton. ISBN 978-0-393-31570-7.
  7. ^ Gould, Stephen J. (2007) [1993]. Eight little piggies. Vintage Books. ISBN 978-0-09-950744-4.