Carl Parow (
Sat, 21 Jan 1995 21:35:08 +1000

> How can we possibly have more ancestors in a coexisting generation than
> the total known population of the earth?
> I know for a fact that I have a mother and a father who each has a mother
> and a father, etc... The direct ancestral chart would look like so:
> Generation Population
> 1 2 (Mother and father)
> 2 4 (grandparents)
> 3 8 (greatgrandparents)....
> 20 1,048,576
> 30 1,073,741,841
> Going backwards it does not take too long to run into a problem.
> What am I missing? Please email your response to me. Thanks

The only explanation I can offer the original poster is contained in the
following article I picked up in one of the genealogy groups some time


Summary of the Shoumatoff article by John Hollenhorst

"The Mountain of Names" by Alex Shoumatoff was published in The New Yorker
magazine on May 13, 1985. Shoumatoff subsequently enlarged the material
into a book of the same title. I have been unable to locate the book here
in Salt Lake City because the only copy was stolen some time ago from our
public library.

First, a statistical whopper: Suppose I calculate the number of ancestors
I have, simply by figuring I have two parents, four grandparents, eight
great-grandparents, sixteen great-great grandparents, and so on, doubling
the number for each generation that I go back in time. If I take this
calculation back to the time of Charlemagne, I would have had
281,000,000,000,000 (that's right, 281 trillion) ancestors, all living at
that one moment in history. Obviously this is impossible.

What prevents this "retrogressive population explosion" from happening?
It's the simple fact that most marriages are between cousins. Therefore we
all share various ancestors, and my own family tree has far fewer people
in it than my calculation would suggest. This is where a theory called
"pedigree collapse" comes into play.

It's estimated that 80 percent of the marriages in world history have
been within at least the second-cousin relationship. It's easy to see
why. Most humans have lived in small towns, villages, tribes, close-knit
religious communities and so on which encourage marriage within a
relatively small universe of possible mates. Obviously this has been
changing a lot in the last couple of hundred years, which should make our
gene pool a little healthier in the long run.

The theory of pedigree collapse is that every person's family tree is
actually shaped something like a diamond. If you trace it back a few
generations, it gets wider. But if you keep going back further into the
generations, it will eventually start to narrow and then finally converge
to a few ancestors, or perhaps even to a single couple. (Adam & Eve?)
Shoumatoff mentions a European monarch in the 19th century who
illustrates the point. The European royal families are so inter-related
that this guy had only 8 great-great grandparents instead of the usual
16! That's because of cousins marrying cousins. Individual progenitors
occupied more than one place in this King's family tree. For example,
maybe the same guy who was his mother's great-grandfather was also his
father's great-grandfather.

Now, the theory of pedigree collapse is that this same phenomenon is
true of all our family trees if you go back far enough. The further back
you go, the more likely it is that an individual ancestor will occupy
more than one spot on your family tree. So the actual numbers of
ancestors at each generational level eventually begins to shrink if you
go back far enough.

Demographer Kenneth Wachter once created a probability model for an
English child born in 1947. By tracing back the generations, he would
have had 60,000 progenitors in approximately 1492. If you take it back
to the time of King John (what's that about 1215 AD?) you would find that
80% of the population of England at that time would be on the family tree
of this hypothetical modern-day Englishman.

That means, essentially, that most people born in modern times in England
are related to one another, most within a few degrees of cousin-hood.

The British gene pool through those 700 or 800 years also includes
people who moved there from the rest of Europe, the Middle East, Asia and
so on. So most people in England today are probably related to almost
everyone in all those other places as well.

And, it turns out, the same is true for all of us!

The human species has only been in existence for about 10,000
generations. The major races (Black, Caucasian, Asian, etc.) only
diverged from one another in the last 1,500 generations, at the most.

Shoumatoff quotes science writer Guy Murchie:

Most geneticists agree that "no human... can be less closely related
to any other human than approximately 50th cousin, and most of us are a
lot closer. The family trees of all of us, of whatever origin or trait,
must meet and merge into one genetic tree of all humanity by the time
they have spread into our ancestors for about 50 generations.

This insight has created a vogue in "horizontal genealogy". It is fun to
discover, for example, that Jimmy Carter and Richard Nixon are 6th
cousins. They share an ancestor named Richard Morris, a Quaker who lived
in pre-Revolutionary New Jersey. Nixon and George Bush are also related:
10th cousin, once removed.

(As a personal aside here, I will note that in Salt Lake City this is a
tactic the Mormon Church uses for impressing the dignitaries who visit.
When a President or world leader or some such pays a call on the church
leaders, the church will sometimes present the visitor with a genealogy
chart to show that he is related to Winston Churchill or Abe Lincoln or
Mahatma Ghandi or some such. If they find axe-murderers on the tree, I
suppose they leave that out.)

Guy Murchie, to each and every one of us: "It is virtually certain that
you are a direct descendant of Muhammed... Krishna, Confucius, Abraham,
Buddha, Caesar, Ishmael and Judas Iscariot.... The earlier they
lived, the more surely you are their descendant."

Shoumatoff: "The political implications of this great kindred are
quite exciting. If all of us could be made aware of our multiple
interrelatedness, if the same sort of altruism that usually exists among
close kin could prevail through the entire human population... [our]
differences... would seem secondary."

It's estimated that about 5 Billion people are alive in modern times.
In the history of the human species about 70 billion to 110 billion of us
are believed to have lived at one time or another.

90% of our species passed into oblivion without leaving a record of
their names. Only about 6 or 7 billion left any kind of a paper trail. Of
those, the Mormon Church has records on 1.5 billion!!!! Shoumatoff
writes, "No genealogical archive is remotely comparable... It is the
closest there will ever be to a catalogue of catalogues for the human

The Mountain of Names in the title refers to a huge nuke-proof vault
full of genealogical records that the Mormon Church maintains in Little
Cottonwood Canyon near Salt Lake City. They use these records to perform
temple rituals which amount to the baptizing of dead ancestors. Don't
worry! They are taking care of all your ancestors too!

I hope you enjoyed this. It fascinates me.

John Hollenhorst.


Hope this helps.