title: Some new thoughts on evolution: the role of the germ layers.
abstract: At an early stage of embryonic development, the animal body divides itself into the three germ layers - the ectoderm, mesoderm and entoderm. It is proposed that this division repeats a fundamental functional differentiation of cells in phylogeny. The tasks of life have been divided into three groups, each germ layer specializing in one of them. The task of the entoderm is metabolism and homeostasis, that of the mesoderm is the structural organization of the body, that of the ectoderm interactions with the environment. In effect, the entoderm is the chemist of the body, the mesoderm its architect and engineer, the ectoderm deals with its external affairs. It is proposed that cognitive and reasoning faculties are inherent in every germ layer and when they separate, they all take an equal share. Each performs its complex and multitudinous tasks by virtue of its faculty of conceptual thought, except that the entoderm and mesoderm began to develop that faculty millions of years before the ectoderm.
authors.forename: S
authors.initials: S
authors.lastname: Seely
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005314:Embryonic and Fetal Development; D008962:Models, Theoretical