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From: "Anatole Klyosov" <>
Subject: Re: [DNA] MRCA Estimates
Date: Sat, 13 Feb 2010 11:59:58 -0500
References: <mailman.339.1266048043.9117.genealogy-dna@rootsweb.com>


> From: Robert Stafford <>
> See this article for an overview:
> http://www.ancestry.com/learn/library/article.aspx?article=11152
> Several people on their own commented about their own genealogies and said
> they had found similar results.

Dear Robert,

You are making four (4) mistakes here. First, you do a "selected
quotation", which often leads to manipulations with numbers for your own
benefit. However, what is your benefit here, I wonder?

You forget to quote the beginning of the paper:

>As a matter of common knowledge, we know that a generation averages about
>25 years-from the birth of a parent to the birth of a child-although it
>varies case by case. We also generally accept that the length of a
>generation was closer to 20 years in earlier times when humans mated
>younger and life expectancies were shorter.

>In genealogy, the length of a generation is used principally as a check on
>the credibility of evidence-too long a span between parent and child,
>especially in a maternal line, has been reason to go back and take a more
>careful look at whether the evidence found reflects reality or whether a
>generation has been omitted or data for two different individuals has been
>attributed to the same person. For that purpose, the 20- and 25-year
>averages have worked quite acceptably; birth dates too far out of line with
>the average are properly suspect.

And the end of the paper:

>In genealogy, conclusions about relationships are subject to change
>whenever better evidence is discovered. Similarly, it's the nature of the
>physical and biological sciences that current understandings are subject to
>change as more data becomes available and that data's interpretation
>becomes more certain. So, for now, when genealogists want to convert
>generations to years and create probable date ranges, using an
>evidence-based generational interval-like Helagason's 30 and 35 years or
>one that you've developed based on your own family history research-may be
>the best solution.


As you see, it may be 30, 35, or whatever, "based on your research". Which
one you insist should be used for TMRCA calculations?

Second your mistake is to quote data collected today, with our
contemporaries.

Third you mistake is to quote just one paper without quoting other papers
which give (and use) 25 years per generation. To quote just one paper and
knowingly do not quote alternative numbers is a manipulation with data.

Fourth your mistake is the most important one. All these "real" years per
generation are irrelevant in my approach. I have explained that I operate in
years, and use "generations" just as a proxy, setting them at 25 years per
generation. It has nothing to do with "real" years per generation which is a
floating "figure" anyway.

Regards,

Anatole Klyosov





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