The species (1): creationism and creationnism with the evolutionism

The species : basic unit of the hierarchy of the alive one

The concept of species intuitive for each is impassioned plants or animal. Practical need for classification, from regrouping of recognizable beings, it is distinguished often, but not always, others.

It is a partial concept: the farmers, the horticulturists, the foresters, the ecologists or the botanists of ground, without speaking of molecular biologists knowing the plants only by the means of the samples of DNA with sequencing, will not have the same design of the species. However, the majority will regard the species as the basic unit of classifications.

Whereas for the foresters, these taxon of pines is quite different and was regarded a long time as distinct species, Pinus will nigra, P. austriaca, P. laricio, P. pallasiana and P. salzmanii belongs to the broad species Pinus will nigra.

The species was the object in the past of many definitions and, currently, none achieves the unanimity because the concept is difficult to model. It is easy to establish an inclusive hierarchy within an individual who can be physically divided into various parts: individual, systems of bodies, body, fabrics, cells, organoids, macromolecules, molecules.

It is, contrary, more difficult to establish a pyramidal hierarchy, i.e. to seek bonds within populations or of species but also to differentiate them from the others. Indeed, the species are not delimited in the time and within the space of the same way as the cells of an individual.

From fixism and creationism to evolutionism

The concept of species standard, immutable, is based on the systems of Plato and Aristote at the 4th century before Jesus Christ. All the individuals of a species are the expressions of the same type; the important variations are regarded as aberrations, imperfect demonstrations of the type.

These ideas included and diffused in Europe medieval and reappearing gave body a design creationnist of the species, and often to creationist, which lasted until the 17th century: the species were created by God for eternity. One century before Linné, John Ray (1628-1705) affirmed that all that the seed of the same plant gives belongs to the same species. For Linné (1707-1778), there are as many species as God created some at the beginning. By defining the species, he wanted to delimit original the “groups” created by God.

If the concept created by Linné to name a plant by a name of kind combined with a name of species is still of topicality, it is not the case for its definition of the species.

The notion creationist of the species starts to be hustled at the 19th century. Jean-Baptiste Lamarck (1744-1829) affirms: “Nature really formed neither classes, neither orders, neither families, neither kinds, nor constant species, but only of the individuals who follow one another the ones the others and which resemble those which produced them… as long as no cause of change acts on them” (opening Speech of year XI, in Cuénot, 1936). For this father of the transformism, the variations of the medium induce hereditary modifications of the species.

The publications of Charles Darwin (1809-1882) gave a final recognition to the theory of the evolution. According to him, the species are not modified but, are not selected by the medium. Survive, by natural selection, only the individuals best adapted (“fitness”). If there exist species very well defined, and recognized by all, that is due to the extinction of the badly adapted forms of passage, and also to various modes of insulation, ecological, sexual, geographical. The well marked varieties would be thus incipient species.