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Archiver > GENEALOGY-DNA > 2006-05 > 1147730280


From: "Alister John Marsh" <>
Subject: Contributions of Phantom Ancestors to our DNA makeup.
Date: Tue, 16 May 2006 09:58:00 +1200
In-Reply-To: <000f01c67839$5f71cb80$bec79045@Ken1>


Lawrence,

You said...
> A) The human genome has only about 25000 functional genes. This means
> that
> beyond about 15 generations back, many 'ancestors' are mere phantoms, who
> have not contributed a single gene to the descendant's genome. Such
> 'ancestry' is meaningless in both science and practice.

It is true that we don't carry a single gene or even base pair in our DNA
directly passed down from many of our ancestors who lived more than 15
generations ago. However, what we are today has been determined by those
phantom ancestors, just as much as the ones who have given us a base pair or
two.

What we are, is determined by what DNA we have, and what DNA we don't have.

Suppose a phantom ancestor 15 generations ago, had a partner who carried a
genetic disorder. Suppose when the DNA was shared out in the offspring, the
phantom ancestor's portion of DNA was passed on instead of the portion with
the genetic disorder. If the phantom ancestor had not blocked the passing
of the genetic disorder down the family line, you may have been carrying
that genetic disorder today, or the affluence and education, or even the
very survival of you family line may have been effected by that disorder. It
may have caused your Y-DNA or mtDNA line to have been killed off before it
reached you, had your phantom ancestor not blocked the passing on of the
genetic disorder.

I consider that every single ancestor, phantom or not, has "impacted"
significantly on the makeup of DNA each of us carries today, even if
strictly we don't carry any base pairs received "directly" from them.
Indirectly, they have affected the DNA we have today.

Also, the culture the phantom ancestors passed on down our line has
"impacted on our DNA". If for example the phantom ancestor's cultural
heritage effected marrying patterns, (eg marrying within a tribe, or outside
a tribe) it will have had an impact on what DNA we have, perhaps in a
disproportionate way. Even an adopted parent can in this way effect the DNA
recombination sequence, and affect the DNA makeup of successive generations.

Our phantom ancestors may not have contributed a gene or a base pair, but
they have never the less effected the combination of genes and base pairs
that we carry today. Would it be "meaningless", if a particular phantom
ancestor has by his existence on your tree, spared you a genetic disorder,
or in a similar way, affected the recombination sequence, enabling you to
receive a beneficial gene from another ancestor living at the time of the
phantom ancestor?

I understand what you were saying, and in the context you said it, it could
be considered you are right. I just wanted to put in a plug for the
"phantoms", lest we forget that they played their role, and we and the world
are changed because they lived.

John.



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