Archiver > GENEALOGY-DNA > 2010-03 > 1268503278

From: "Diana Gale Matthiesen" <>
Subject: Re: [DNA] Clades, Definitions, Discoveries, FTDNA
Date: Sat, 13 Mar 2010 13:01:18 -0500
References: <><><><00e201cac145$82fec7c0$5e82af48@Ken1><><017901cac159$4e6c7020$5e82af48@Ken1><086F1093A566477B815995B401BB889C@HP><><><000601cac1f5$b5338040$5e82af48@Ken1><294168F50E07487A812B78EBD02BCBF4@HP><><BCC91D9EA86E43FCBF0F1AEAFB5CD7A7@HP><011b01cac212$8b6e9340$5e82af48@Ken1><65609D4617B84F15B9653A789115A218@HP><>
In-Reply-To: <>

With all due respect, Vincent, you don't seem to have even the remotest
understanding of the nature of the Y-DNA haplotree, cladistics, or clades.

Y-DNA haplogroups (clades) are not defined by their demographic properties, they
are defined by the polarity of their SNP mutations. They do not arise out of
demographic conditions, they arise via mutation, and their boundaries are
determined by their position on the Y-DNA SNP cladogram (haplotree). Such
clades may have demographic properties, but those properties have absolutely
nothing to do with the definition (or boundaries) of the clade.

Yes, the descendants of a single common ancestor do form an evolutionary clade.
My father's descendants are a clade; my grandfather's descendants are a
different clade -- every human being is the root of a unique clade. But your
"demographic groups" contain more than the descendants of a single person. That
makes these groups polyphyletic, not monophyletic, which means they're not
evolutionary clades, they're populations ("demographic groups").

Please note that, at the outset, I expressly excluded the issue of family-level
relationships based on STR haplotypes, which is an entirely different matter.
There is no Y-DNA STR cladogram of any depth beyond recent families in
genealogical time, and I know of no male who, alone, has formed his own
monophyletic population. The first time a daughter married outside the family,
the population became polyphyletic and ceased to be a clade.

This obfuscation between the nature of clades and populations is, IMO,
detrimental to useful discussion of human phylogeny, which is the reason I
periodically jump in and object to it.


> -----Original Message-----
> From: On Behalf Of Vincent Vizachero
> Sent: Friday, March 12, 2010 2:51 PM
> To:
> Subject: Re: [DNA] Clades, Definitions, Discoveries, FTDNA
> With all due respect, Diana, I don't think you really understand the
> thing you are criticizing here.
> A clade is defined (or choose your preferred term) entirely by
> demographics. A clade exists whenever someone or something has
> descendants. The set which includes that MRCA and his/her/its
> descendants is a clade. That's pretty simple, but its an accurate
> description.
> Ken's point is that whether or not a clade comes into being
> is largely
> down to demographic factors: population sizes, population growth
> rates, and so on. If the right demographic conditions
> manifest, clade
> creation happens. If the right conditions don't manifest, no clades.
> So these clades exist, whether or not someone clever comes along to
> "discover" them or not. And they exist whether or not someone is
> clever enough to find a SNP to "define" them or not.
> It just so happens that, among western Eurasians in historic times,
> Jews (especially Ashkenazi Jews) have been characterized by
> demographics that made it more likely that easily defined
> clades came into existence.
> VV

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