Aristotle Transformationism And Epigenesis Analysis

Aristotle, one the first philosophers to adopt empiricism, wrote in his Metaphysics “it is owing to wonder that people began to philosophize, and wonder remains the beginning of knowledge”. He is regarded as the first embryologist known to history for his extensive studies on the reproduction and early growth of animals and humans. Aristotle proposed two theories that attempted to explain the development of organisms: preformationism (pre-formed), which proposes that the morphology and structures of adult organisms exist from the moment of fertilization and humans and animals simply grow proportionally, and epigenesis (upon formation), which states that new and more complicated structures arise progressively from simple ones. In part due to

Such a force was inherited via the sperm and egg (together called germ cells) and remained in all cells during the life of the organism. Its role was to carefully guide the formation of new tissues or the regeneration of damaged ones. With the Bildungstrieb Kant and Blumenbach popularized the notion that even if development does not proceed by pre-formed structures, it is guided by a pre-set of instructions transmitted by the germ cells, and such instructions also allowed organisms to respond and adapt to environmental challenges. After this change in paradigms, the following centuries saw two mayor waves of discoveries that have shaped our current understanding of developmental biology: the first were descriptive and the second

He emphasized the difference between the cells that compose the body (somatic cells) and those that will generate a new organism (i.e., the germ cells). By then, it was known that the offspring inherits its characteristics not from the somatic cells but from the germ cells. Indeed, 18th century scientists view the sperm and the egg as the most important cells; the rest of the body was reduced to a mobile reservoir of germ cells. This idea was better expressed by the English author Samuel Butler, who wrote: “A Hen is only an egg´s way of making another egg”. Therefore, in order to understand the fundamental mechanisms behind development, Weismann and many others focused their efforts in studying the process of fertilization as the crucial step of development. This led to the important observation that the fertilized egg contains two nuclei that eventually fuse. Considering the fact that the matter in the cytoplasm of the sperm is neligible compared to the egg, Weismann reasoned that only the nucleus could account for the even distribution of paternal and maternal characteristics; in other words, the nuclei contained the “developmental force” that was the basis of