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orthogenesis

 - 4 dictionary results
Orthogenic School
Official Site of Sonia Shankman Orthogenic Residential School.
OrthogenicSchool.uchicago.edu

or⋅tho⋅gen⋅e⋅sis

  [awr-thuh-jen-uh-sis]
Use orthogenesis in a Sentence
–noun
1. Biology.
a. Also called orthoselection. evolution of a species proceeding by continuous structural changes in a single lineage without presenting a branching pattern of descent.
b. a theory that the evolution of a species in a continuous, nonbranching manner is due to a predetermined series of alterations intrinsic to the species and not subject to natural selection.
2. Sociology. a hypothetical parallelism between the stages through which every culture necessarily passes, in spite of secondary conditioning factors.
Origin:
1890–95; < NL; see ortho-, genesis
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
Cite This Source Link To orthogenesis
Orthogenic School
Official Site of Sonia Shankman Orthogenic Residential School.
OrthogenicSchool.uchicago.edu
or·tho·gen·e·sis   (ôr'thō-jěn'ĭ-sĭs)   
n.  

  1. Biology The theory that the evolution of a species is influenced most strongly by internal factors and is not subject to the external forces of natural selection.

  2. The theory that all cultures pass through sequential periods in the same order.

or'tho·ge·net'ic (-jə-nět'ĭk) adj., or'tho·ge·net'i·cal·ly adv.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Medical Dictionary

Main Entry: or·tho·gen·e·sis
Pronunciation: "or-th&-'jen-&-s&s
Function: noun
Inflected Form: plural or·tho·gen·e·ses /-"sEz/
: variation of organisms in successive generations that in some evolutionary theories takes place in some predestineddirection and results in progressive evolutionary trends independent of external factors —or·tho·ge·net·ic /-j&-'net-ik/ adjective
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Encyclopedia

orthogenesis

theory that successive members of an evolutionary series become increasingly modified in a single undeviating direction. That evolution frequently proceeds in orthogenetic fashion is undeniable, though many striking features developed in an orthogenetic group appear to have little if any adaptive value and may even be markedly disadvantageous. A variety of theories have attempted to explain orthogenesis, but with only partial success.

Learn more about orthogenesis with a free trial on Britannica.com.

Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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