THE SPECIES CONCEPT
The earliest work of the systematists emphasized the similarities of individuals within species and the sharp distinctions between individuals of diverse species. This view was an inheritance from man's primitive knowledge of plants and animals, and one which, bolstered by a widespread misinterpretation of the doctrine of the uniformity of nature, is still widely held outside of scientific circles today.
As the facilities for the more careful examination of individuals were developed early in the last century, scientific emphasis was shifted to the fact that no two individuals are exactly alike, and the species problem resolved itself into a search for the factors of evolution. As a direct result of those investigations there has developed a growing conviction that individuals are the only realities in nature, and an agreement that species are only convenient concepts originating and ending in the minds of scientists. This is the basis of recent demands that we return to what is, curiously, called the Linnean species, it being argued that that was as near reality as any present-day concept, and an article far more ready for the use of those who are not taxonomic specialists. Taxonomists have contributed little to the resolution of this confusion, for many of them are bewildered at the array of geographic variants and transition zone hybrids which have recently become available particularly from our own continent, and species are frankly defined in the codes as concepts that may be standardized and established by quasi-legal verbiage.
One wonders to what extent this confusion as to the nature of species has delayed our understanding of the origin of species. Perhaps it is this confusion which leaves us without a convincing reply for the fundamentalists who insist that data from the evolution of domesticated plants and animals and from laboratory genetics may explain the origin of varieties but not of species. There is a peculiarly hollow ring to our statement that varieties are incipient species and that the evolution of species is too slow a process for human observation. Moreover, the illogical sequence in most of our texts, where the evolution materials are followed by the data of heredity, is some evidence that the geneticists do not perceive the application of their laboratory findings to species
