Epigenesis (biology)

For features that are stable over rounds of cell division but do not involve changes in the underlying DNA sequence of the organism, see epigenetics.

In biology, epigenesis has at least two distinct meanings:

• the unfolding development 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 and organs form;
• the theory that plants and animals develop in this way, in contrast to theories of preformationism.

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

A well-known example of epigenesis is that of the honey bee. Larvae that are fed with a pollen and nectar diet develop into worker bees, while those fed royal jelly develop into queens, growing larger and with different morphology.

See also

• Epigenetics
• Epigenetic Theory

External links

• Aristotle: On the Generation of Animals (extracts)
• Epigenetic+Process at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
• Template:EMedicineDictionary