Re: Claims of Royal Descent

Don Aitken skrev:

Yup, got it. It seems rather peripheral to the main issue, though.

Indeed. I jumped on it because it wasn't stringent, and went in the
same direction as that of "gro", who oversells the concept
considerably.

Coincidentally, I've just got the new biography of Edward III by Ian
Mortimer. Presumably to justify his subtitle "Father of the Engliah
Nation", Mortimer, who is a scholar of the social history of medicine
as well as a medievalist, devotes an appendix to discussion of how far
this frequently encountered description of Edward is literally true.
His methodology is fairly sophisticated.

He begins by counting the number of known descendants alive in England
in 1500 (123 years after Edward's death), and makes it 436 (out of a
total of about 2.75 million). He excludes those born about 1500 whose
exact date of birth is unknown, those who married abroad or in
Scotland or Wales and their descendants, and all illegitimate
descendants except the Beuforts, hence this is a very conservative
number; the true figure may well be more than a thousand.

´this is a _very_ high figure for such a short trimespan, even taking
into account that Edward lived long, such that the. Clearly Edward III
i a very "stong ancestor".

He then determines what proportion of this generation married other
Edward III descendants, and finds this figure to be 13%. He then
applies this factor to subsequent generations, calculating the numbers
by doubling, then applying the "correction factor" of 100/113. This
makes the proportion of descendants in the population increase to just
under 15% by 1860.

This seems quite conservative. One would expect that the true
correction factor would gradually decrease. The doubling is more
arbitrary, but this is conseravative, too. A doubling of the
descendants in the effective (reproducing) population is what is needed
in a stable, non-growing population, because the to reproducing parents
then are replaced by two repreoducing offspring.

At some point, however, the correction factor becomes inappropriate,
as descendants as a whole are no longer socially distinct from
non-descendants. He ceases to apply it at 1860, with the result that
the proportion of descendants reaches 90% for those born in 1980, and
99% for those born in 1995.

It can't have made all that much of a difference if ha had ceased to
apply the correction at that time.

After considering various other factors, he concludes, cautiously,
that "we may regard Edward III as being a common ancestor of well over
80% probably over 95% - of the living English-descended population of
England".

This seems entirely justified. But then, England is a country with
conspicuously weak natural geogrephical barriers.

If this is even approximately right, the proportion for someone living
550 years earlier than Edward III must be as near 100% as makes no
difference, even taking into account the fact that we are dealing with
a wider area.

This is depends entirely on how wide the area is, or, rather, what
mating limitations there are over it. (The vast surface of the United
States has very little geographical mating limitation within it,
whereas the inhabitants of a Swiss Alp valley for long functioned as
an essentially self-sufficient reproducing population.) .In the absence
of knowledge of what limitations a given geography has imposed, there
isn't much point in trying to guess how many generations further back
an ancestor has to be placedhas to know what barriers are to be
overcome, before concluding that a an ancestry placed a certain number
of generations further back certainly will compensate - in particular
as we know much less about migration and mating patterns, the further
back we go in history.

Jan Böhme

.

Relevant Pages

  • Re: Impoverished descendants of Edward III
    ... Impoverished descendants of Edward III ... Matthew's father was George Dodsworth, son of Simon Dodsworth and elder brother of the Matthew Dodsworth in the Wikipedia page. ... Peter Roos of Laxton Hall in Nottinghamshire, ...
    (soc.genealogy.medieval)
  • Re: Impoverished descendants of Edward III
    ... Impoverished descendants of Edward III ... Matthew's father was George Dodsworth, son of Simon Dodsworth and elder brother of the Matthew Dodsworth in the Wikipedia page. ...
    (soc.genealogy.medieval)
  • Re: Impoverished descendants of Edward III
    ... Impoverished descendants of Edward III ... Peter Roos of Laxton Hall in Nottinghamshire, ... Jane Warter m. Marmaduke Dodsworth ...
    (soc.genealogy.medieval)
  • Re: Early ancestors
    ... suggesting that 80% of people living about ... the other 20% were ancestors of nobody alive today. ... Mortimer's recent biography of Edward III. ... descendants several generations later; in 1500 there were 436 of them. ...
    (soc.genealogy.britain)
  • Re: DESCENDANTS OF HENRY IV OF ENGLAND
    ... why didn't they succeed to the throne after the death of Edward ... IV and the presumed deaths of his sons? ... The long-term result was that the descendants of Richmond -- ...
    (alt.talk.royalty)