The NSS Bulletin - ISSN 1090-6924
Volume 47 Number 2: 71-77 - December 1985
A publication of the National Speleological Society

Regressive Evolution: An Historical Perspective
T.C. Kane and R.C. Richardson

Abstract

Explanations of the evolutionary causes for the reduction or loss of eyes and pigment in cave animals have been controversial since the time of Lamarck and Darwin. The absence of any clear selective advantage to such reduction has led biospeleogists to consider a variety of mechanisms underlying their existence. During the latter half of the nineteenth century, regressive evolution was used as strong evidence supporting the neo-Lamarckian theory of the effects of disuse and the inheritance of acquired characteristics. At the beginning of the twentieth century, the establishment of Mendelian mechanism of inheritance undermined this theory, but left evolutionary biologists lacking a mechanism for regressive evolution. Although the neo-Larmarckian hypothesis is no longer tenable, modern theories of regressive evolution-including appeals to energy conservation, indirect effects of pleiotropy, and the accumulation of neutral mutations-can all be seen as developments which emerge as answers to problems formulated in the nineteenth century, and which have nineteenth century precursors.

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