Dollo's Law

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Dollo’s Law


(the doctrine of irreversibility of evolution), a doctrine first clearly formulated in 1893 by the Belgian paleontologist L. Dollo. According to Dollo, an organism cannot revert, even in part, to its former state through which several of its ancestors have already passed. For example, land vertebrates in the course of secondary adaptation to life in water do not become fish again nor do they acquire the characteristics peculiar to fish (for example, gills). That is why ichthyosaurs, which became adapted to an aqueous environment, remained in all their structural features typical reptiles; similarly, whales remained mammals with their own special structural features.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Louis Antoine Marie Joseph Dollo (1857-1931) enunciated the Dollo's principle (law or rule) that evolution is irreversible, i.e.