Evolutionary Science has, at least since the publication of Origin, been less concerned with the con- tinuation of species in stable forms, than with the recon- figuration of forms into a host of varieties. So influential has this emphasis been that, over the years, ‘‘variation’’ has become a cardinal desideratum, even taking precedence over the macroevolutionary landscape. This orientation has made it much more difficult to objectively assess the meaning of non-change patterns such as periods of stasis, which appear to be widespread in most species. Yet, if stasis is an expectable outcome of evolutionary activity, this raises the possibility that there may be mechanisms and processes at many causal levels, acting on its behalf, without reference to the impetus toward persistent varia- tion. Researchers have been reluctant to attribute stasis to a macroevolutionary tendency toward ‘stability’ despite the commonality of stasis in many species, and notwithstand- ing the many biological/behavioral processes that seem inclined to produce and maintain conformance, regulation and consistency. Speciation, paradoxically, is the best evidence for an overriding influence toward stability in that stability would seem to be a necessary condition prior to the development of isolating mechanisms. An alternative macroevolutionary model of biological activity is offered consisting of two tendencies, ‘‘variety’’ counterpoised with ‘‘stability’’ both acting in the service of the persistence of life.
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