CHAPTER THREE 



Evidences of Evolution 



II: Taxonomy, Comparative 



Anatomy, a7id Embryology 



The second major category of evidence for evolution is taxonomy, the 

 science of the classification of organisms. Classification would be abso- 

 lutely necessary because of the sheer numbers of species, even if no other 

 purpose beyond that of facilitating study were to be served. There are 

 something on the order of 1,000,000 species of animals and 250,000 species 

 of plants described in biological literature. Large numbers of these may 

 live even in very restricted locahties. Thus, in Lake Maxinkukee, Indiana, 

 Jordan identified sixty-four species of fish, eighteen species of amphibians, 

 and 130 species of molluscs. This does not infer that other groups may not 

 be as liberally represented, but simply that they are not cited. It is evident 

 that no extensive and orderly study of the living world would be possible 

 unless it be divided into categories about which generalizations could be 

 made. 



LINNAEUS AND BIOLOGICAL NOMENCLATURE 



Modern classification is based upon the work of Carolus Linnaeus, a 

 Swedish botanist (1707-1778) who undertook the classification of the 

 entire living world. Previously, scientific names of organisms had been 

 short ( or not so short! ) descriptions written in Latin. Thus, Mark Catesby 

 in 1754 referred to the red-headed woodpecker as Picas capite toto riibro 

 and to the red-winged blackbird as Sturnus niger alls swperne ruhentihus. 

 Linnaeus introduced the practice of giving each animal a binomial name, 

 the first member of which is the generic name, and is shared with other 

 closely similar species; while the second member, the specific name, dif- 

 ferentiates the species from other members of the same genus. This bi- 

 nomial system of nomenclature is now universally accepted. Thus, the 

 red-headed woodpecker becomes Mekinerpes erijthrocephalus and the 

 red-winged blackbird becomes simply Agelaius phoeniceiis. 



The Species Concept. Basic to this is the species concept, the idea that 

 there are definite kinds of plants and animals, the individuals of any one 



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