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'''descend'''

'''descend'''

   

   

c.1300, from O.Fr. descendre, from L. descendere, from de- "down" + scandere "to climb," from PIE base *skand- "jump." Sense of "originate from" is c.1375. Descent is attested from c.1330; descendant "offspring" is from 1600.

c.1300, from Old.French. descendre, from L. descendere, from de- "down" + scandere "to climb," from PIE base *skand- "jump." Sense of "[[origin]]ate from" is c.1375. Descent is attested from c.1330; descendant "offspring" is from 1600.

Online Etymology Dictionary, © 2001 Douglas Harper

In [https://en.wikipedia.org/wiki/Evolutionary_biology evolutionary biology], a group of [[organisms]] have common '''descent''' if they have a common [[ancestor]]. "There is strong [[quantitative]] [[support]], by a [[formal]] test" for the [[theory]] that all living [[organisms]] on [[Earth]] are descended from a common ancestor.

'''''Ascending and Descending''''' is a [[Lithography|lithograph]] print by the [[Netherlands|Dutch]] artist [[M. C. Escher]] which was first printed in March [[1960]].

The last [[universal]] [[ancestor]] (LUA) (or last universal common ancestor, LUCA), that is, the most recent common ancestor of all currently living [[organisms]], is believed to have appeared about 3.9 billion years ago.

The original print measures 14" x 11 1/4”. The lithograph depicts a large building roofed by a never-ending [[staircase]]. Two lines of identically dressed men appear on the staircase, one line ascending whilst the other descends. Two figures sit apart from the people on the endless staircase: one in a secluded courtyard, the other on a lower set of stairs. While most two-dimensional artists use relative proportions to create an illusion of depth, Escher here and elsewhere uses conflicting proportions to create the visual paradox.

In [https://en.wikipedia.org/wiki/The_Ancestor%27s_Tale ''The Ancestor's Tale''], [https://en.wikipedia.org/wiki/Richard_Dawkins Richard Dawkins] coined the word concestor, as a substitute for common ancestor or most recent common ancestor. This new [[word]] is very gradually entering [[scientific]] parlance.

==Descent and the family==

Descent, like [[family]] systems, is one of the major [[concepts]] of [[anthropology]]. [[Cultures]] worldwide [[possess]] a wide range of systems of tracing kinship and descent. Anthropologists break these down into simple [[concepts]] about what is [[thought]] to be common among many different cultures.

A ''descent group'' is a [[social]] [[group]] whose members claim [[common]] [[ancestry]]. A unilineal [[society]] is one in which the descent of an [[individual]] is reckoned either from the [[mother]]'s or the [[father]]'s line of descent. With matrilineal descent individuals belong to their mother's descent group. ''Matrilineal descent'' includes the mother's brother, who in some societies may pass along [[inheritance]] to the sister's children or [[succession]] to a sister's son. With ''patrilineal descent'', [[individuals]] belong to their father's descent group. Societies with the [https://en.wikipedia.org/wiki/Iroquois Iroquois] kinship system, are typically uniliineal, while the Iroquois proper are specifically matrilineal.

''Ascending and Descending'' was influenced by, and is an artistic implementation of, the [[Penrose stairs]], an [[impossible object]]; [[Lionel Penrose]] had first published his concept in the February, [[1958]] issue of the ''[[British Journal of Psychology]]''. Escher developed the theme further in his print ''[[Waterfall (M. C. Escher)|Waterfall]]'', which appeared in [[1961]].

In a [[society]] which reckons descent bilaterally (bilineal), descent is reckoned through both father and mother, without unilineal descent groups. Societies with the [https://en.wikipedia.org/wiki/Eskimo Eskimo] kinship system, like the Eskimo proper, are typically bilateral. The egocentrid kindred group is also typical of bilateral societies.

Some [[societies]] reckon descent patrilineally for some [[purposes]], and matrilineally for others. This arrangement is sometimes called double descent. For instance, certain [[property]] and titles may be inherited through the [[male]] line, and others through the [[female]] line.

* [http://www.voidgamers.com/channel/HirstArts/HADD7/b.356.r.386.html Ascending and Descending] A wonderful 3D forced perspective model was build as part of a kit building contest

 

*Locher, J.L. (2000). ''The Magic of M. C. Escher''. ISBN 0-8109-6720-0.

[[Category: General Reference]]

[[Category: General Reference]]