Epigenesis (biology)
Encyclopedia
In biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, epigenesis has at least two distinct meanings:
  • the unfolding development
    Morphogenesis
    Morphogenesis , is the biological process that causes an organism to develop its shape...

     in an organism, and in particular the development of a plant or animal from an egg or spore through a sequence of steps in which cells differentiate
    Cellular differentiation
    In developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of...

     and organs form;
  • the theory that plants and animals develop in this way, in contrast to theories of preformationism
    Preformationism
    In the history of biology, preformationism is either the specific contention that all organisms were created at the same time, and that succeeding generations grow from homunculi, animalcules, or other fully formed but miniature versions of themselves that have existed since the beginning of...

    .


The originator of this theory of epigenesis was Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

 in his book On the Generation of Animals. Though the theory seems an obvious fact to us in today's genetic age, however, the theory was not given much credence in former times because of the dominance for many centuries of Creationist
Creationism
Creationism is the religious beliefthat humanity, life, the Earth, and the universe are the creation of a supernatural being, most often referring to the Abrahamic god. As science developed from the 18th century onwards, various views developed which aimed to reconcile science with the Genesis...

 theories of life's origins. However, during the late 18th century an extended and controversial debate by biologists finally led epigenesis to eclipse the long-established preformationist view.
The embryologist, Caspar Friedrich Wolff
Caspar Friedrich Wolff
Caspar Friedrich Wolff was a German physiologist and one of the founders of embryology.-Life:Wolff was born in Berlin, Brandenburg. In 1230 he graduated as an M.D...

, famously refuted preformationism in 1759 in favor of epigenesis, though this did not sound the death knell of preformationist ideology.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK