what is "pedigree collapse"?

+10 votes
306 views
I've seen that term used but not defined.
asked in The Tree House by Foster Ockerman G2G6 Mach 3 (34k points)
retagged by Ellen Smith
Do a Google search of the definition of the term pedigree collapse

You will find lots of hits.

Also, scroll down this page to see links to earlier G2G posts on the subject of pedigree collapse. And one that isn't listed there: If Your Ancestors Married Their Cousins, Are You Embarrassed or Excited? 

Whatever it is I think it is contagious, especially in villages and small rural towns.  :D

2 Answers

+12 votes
 
Best answer

Pedigree Collapse,

In genealogy, pedigree collapse describes how reproduction between two individuals who knowingly or unknowingly share an ancestor causes the family tree of their offspring to be smaller than it would otherwise be. The term was coined by Robert C. Gunderson, first supervisor of the Genealogical Society of Utah's Royalty Unit. Pedigree Collapse is also known by the German term AHNENSCHWUND which roughly translated as "loss of lineage"

How it works.

Without pedigree collapse, a person's ancestor tree is a binary tree, formed by the person, parents, grandparents and so on. However, the number of individuals grows exponentially and will eventually become impossibly high. For example, ​a single ins the binary tree individuals alive today would, over​ 30 Generations going back to the Middle ages.​ have roughly a billion ancestors, ​more than the total world population at the time​. This apparent paradox occurs because the individuals in the binary tree are not distinct; instead, a single individual may occupy multiple places in the binary tree. This typically happens when the parent's of an ancestor are cousins, (/wiki/Cousin) (some times unbeknown to themselves). For example, the offspring of two first cousins has at most only six great grandparents instead of the normal eight. This reduction in the number of ancestors is ​Pedigree Collapse​. It collapses the binary tree into a directed acyclic graph with two different, directed paths starting from the ancestor who in the binary tree would occupy two places.

In some cultures, cousins were encouraged to or required to marry  to keep kin bonds, wealth and property within a family (endogamy) (/wiki/Endogamy). Among royalty, the frequent requirement to only marry other royal's resulted in a reduced gene pool.

The full article can be found at:-, http://www.i.org/windex.ph_pree?title+pedigree_collapse&oldid=18306

 

answered by Doug Stewart G2G6 (6.6k points)
edited by Doug Stewart
Got it.  Thanks.
+6 votes
answered by Michael Stills G2G6 Pilot (360k points)
Thanks Micheal. That sent me to alot of new places. I had a pleasant trip.

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