This collection of revised and new essays argues that biology is an autonomous science rather than a branch of the physical sciences. Ernst Mayr, widely considered the most eminent evolutionary biologist of the 20th century, offers insights on the history of evolutionary thought, critiques the conditions of philosophy to the science of biology, and comments on several of the major developments in evolutionary theory. Notably, Mayr explains that Darwin's theory of evolution is actually five separate theories, each with its own (...) history, trajectory and impact. Ernst Mayr, commonly referred to as the "Darwin of the 20th century" and listed as one of the top 100 scientists of all-time, is Professor Emeritus at Harvard University. What Makes Biology Unique is the 25th book he has written during his long and prolific career. His recent books include This is Biology: The Science of the Living World (Belknap Press, 1997) and What Evolution Is (Basic Books, 2002). (shrink)
In the Preface of Animal Species and Evolution (1963), I wrote that it was "an attempt to summarize and review critically what we know about the biology and genetics of animal species and their role in evolution." The result was a volume of XIV ...
I analyze a number of widespread misconceptions concerning species. The species category, defined by a concept, denotes the rank of a species taxon in the Linnaean hierarchy. Biological species are reproducing isolated from each other, which protects the integrity of their genotypes. Degree of morphological difference is not an appropriate species definition. Unequal rates of evolution of different characters and lack of information on the mating potential of isolated populations are the major difficulties in the demarcation of species taxa.
WE HAVE LEARNED in the preceding chapter that a revolutionary change of the species concept is in the making, a change which not only affects taxonomic procedure, but which also contributes considerably toward a better understanding of ...
It is evident how much Olby and Provine have contributed to a better understanding of the emergence of genetics. It is equally evident, I believe, how many obscure issues still remain to be elucidated. Indeed, their volumes have raised as many new questions as they have answered old ones. In particular, the role of constructive as well as retarding contemporary concepts in the development of new generalizations still requires far more analysis. The somewhat independent trends of various national schools and (...) the influence of neighboring fields (e.g. statistics, animal husbandry, systematics) are other areas deserving further study. All these influences contributed, one way or another, to the growth and maturation of genetics.37. (shrink)
A theory may be invalid, not owing to erroneous observations or the invocation of an inappropriate law, but because of the use of equivocal terms. This is demonstrated for Darwin's failed model of sympatric speciation through the principle of divergence.
The biological species concept deals both with the meaning of the sexual species as a harmonious gene pool and with its protection against deleterious outbreeding (effected by isolating mechanisms). According to the Darwin-Muller-Mayr theory isolating mechanisms are acquired by incipient species during alloparty. Isolating mechanisms are not the result of ad hoc selection, but of a change of function of properties acquired during the preceding isolation of the incipient species. The role of behavioral properties (recognition) among the isolating mechanisms has (...) long been recognized and described by naturalists but was rejected as basis of a species definition for a number of valid reasons. (shrink)
The type in taxonomy is not meant to be a particularly typical specimen, but simply a reference specimen suited to serve as a 'name bearer' whenever doubt arises concerning the identity of a species. The minimum requirement is that the specimen reflects some differentiating characteristics of the species. In analogy, only such individuals should be made the type of an ideological system as adhere to the principal ideologies of that system. Only such an evolutionist could serve as type for Darwinism (...) who on the whole accepts gradual evolution and, as the major moving force in evolution, natural selection. It is very questionable whether the type-method would be of any use where highly heterogeneous, open, or rapidly evolving systems are involved. When the meaning of a system is changing it is less confusing to redefine it than to coin a new term for each change. (shrink)
Four ordering systems have been used most frequently in taxonomy: (1) special purpose classifications, (2) downward classifications (identification schemes), (3) upward or grouping classifications (traditional), and (4) Hennigian phylogenetic systems. The special properties of these four systems are critically evaluated. Grouping classifications and phylogenetic systems have very different objectives: the former the documentation of similarity and closeness of relationship, the latter of phylogeny. Both are legitimate ordering systems.
Modern Darwinism is an elaboration of Darwin's original theories. The misunderstandings of the synthetic theory, on which recent attacks are based, are analyzed in detail. Six areas are described in which current theory modifies or amplifies Darwin's thinking. The rejection of an inheritance of acquired characters, the greater role assigned to chance in the production of genetic variability, the knowledge of the total separation of genotype and phenotype, and the clearer recognition of the role of the individual as target of (...) selection, are among the modern amplifications of the Darwinian theory. Remaining gaps in our understanding of evolution are specified. (shrink)