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Archiver > GENEALOGY-DNA > 2002-02 > 1012591317


From: "Allan S. Gleason" <>
Subject: Re: [DNA] How many years is a Generation?
Date: Fri, 01 Feb 2002 12:21:57 -0700
References: <173.304e59c.298c1363@aol.com>


Hi Paula,
The 'professional' definition of a generation seems to be 20 years although Relative
Genetics uses 25 years. My own database yields about 26 years for women with a
range of from 14 to 50. The male average was from about 18 to 70 with the average
being about 31. The time period for my statistics was from about the 1400's to the
1900's. Breaking the statistics down into century-long groups revealed that parents
were older on average in the 16-1700's than in the 1900's! (I use 'abouts' because
I don't want to bother looking them up right now).
Allan


wrote:

> It seems there are three different generational averages needed.
>
> 1) The shortest number of years would be used when calculating female to
> child (mtDNA) average generation time.
>
> 2) The second generation type would be used when needing average years from
> parents (either sex) to children. (autosomal chromosomes) This is the one we
> usually think of.
>
> 3) The longest generation time would be used when trying to estimate the
> paternal line (Y lines), male to child average years.
>
> This is because women seldom have children over the age of 45 and men
> continue having children much later (up to 70 years in my family records)
> which changes their average.
>
> Over thousands of years the male Y chromosome is handed down many fewer times
> on average than mtDNA. This would also affect any mutation rate calculations
>
> Men and women do have different generational times! I just don't know what
> they are.
>
> If I am way off track here feel free to set me on the right course. ~Paula~
>
> ==============================
> To join Ancestry.com and access our 1.2 billion online genealogy records, go to:
> http://www.ancestry.com/rd/redir.asp?targetid=571&sourceid=1237

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