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Tempo and Mode in Evolution: Punctuated Equilibria and the Modern Synthetic Theory

Published online by Cambridge University Press:  01 April 2022

Paul Thompson*
Affiliation:
Department of Philosophy, University of Toronto, Scarborough College

Abstract

Several paleontologists have recently challenged the explanatory adequacy of the modern synthetic theory of evolution. Their position is that, contrary to the prevailing view that evolutionary change is gradual, the fossil record manifests long periods of species stasis (equilibrium) punctuated by periods of rapid species formation. And, they argue, this punctuated equilibria pattern challenges the gradualist, adaptationist and extrapolationist assumptions of the modern synthetic theory of evolution and supports a hierarchical, non-extrapolationist (non-reductionist) view of evolution. In this paper I argue that the challenge rests on an inadequate characterization of the modern synthetic theory and that, even accepting punctuated equilibria and an irreducible evolutionary hierarchy, the modern synthetic theory is adequate to explain evolutionary change at all levels of the hierarchy.

Type
Research Article
Copyright
Copyright © Philosophy of Science Association 1983

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Footnotes

I am very grateful to Thomas Goudge, David Hull, Michael Ruse, and the referee for this journal for helpful comment on earlier drafts.

References

1 Alexander Rosenberg (1981) has convincingly argued against Ruse's strong claim that population genetics is the central core of evolutionary theory.

2 On some definitions of ‘species', this is not a form of speciation. In these cases, branching lineages constitute part or all of the meaning of ‘species'.

3 Gould (1982, p. 383) has recently made clear that the debate does not depend on semantics concerning time. He accepts that his use of the expression ‘geological instant’ is quite consistent with the time requirements of orthodox speciation views. It is not the implications of punctuated equilibrium for tempo but for evolutionary theory that most concern him.

4 For an excellent discussion of the issues of hierarchy and selection see Hull (1980).