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Q: Minimum number of humans for viable space colony? ( Answered,   3 Comments )
Subject: Minimum number of humans for viable space colony?
Category: Science > Biology
Asked by: deminimis-ga
List Price: $20.00
Posted: 25 Jul 2004 13:41 PDT
Expires: 24 Aug 2004 13:41 PDT
Question ID: 378894
What is the minimum number of humans, both male and female, that would
be required (with a strict breeding program) to ensure a viable,
long-term human colony on another planet?

Alternatively, what is the minimum number of humans, both male and
female, that would be required without strict limitations on whom one
could breed with?

I remember this question being answered during some C-SPAN panel on
Mars colonization.  I think the answer to the strict-breeding question
was something like 27 humans, but never went into specifics.  If you
could provide references--cites in scientific journals--for instance,
detailing how such a breeding program would operate through the
generations, I would be greatly appreciative.

Since I am not a mad scientist, my interest in this question is purely academic.  :)
Subject: Re: Minimum number of humans for viable space colony?
Answered By: tutuzdad-ga on 25 Jul 2004 15:15 PDT
Dear deminimis-ga

Thank you for allowing me an opportunity to answer your interesting
question. The answer of course is not proven so it would depend
largely upon who one asks, but the question has been given some
thought in the past relative to certain hypothetical situations. I was
unable to find anything even remotely reliable in terms of outlining
or describing a ?strict breeding program? but I did find that some
research (as you suggested alternatively) had been conducted and
theorized by a reliable source, who speaks of various plans related to
the number of travelers necessary to accomplish a long-term mission in

Anthropologist John Moore of the University of Florida has studied
this issue extensively and while others have considered scientific
ways of procreation (cryogenics, artificial insemination, etc) he has
focused primarily on propagating new inhabitants, new sojourners and
new pilots during the flight duration by way of common mating and
natural selection. WHITLEY STRIEBER?S UNKNOWN COUNTRY outlines some of
Moore?s theories:

?Researchers are trying to figure out the ideal number of people
needed to create a viable population for multi- generational space
travel. They?ve decided it needs to be 160 people. But with some
social engineering it might even be possible to reduce this to 80.?

?Moore has previously studied small migrating populations of early
humans and has developed simulation software called Ethnopop that
analyzes the reproductive viability of small groups. A space trip of
200 years would perhaps take eight to 10 generations, and for this,
his calculations suggest a minimum number of 160 people are needed to
maintain a stable population. This would produce around 10 potential
marriage partners per person??

Moore goes on to say that there are more options than just the
obvious. Imposing significant self-control could expand each
generation by a dozen or so years, thereby stretching out the periods
of new births over a much longer period of time and reducing the
minimally necessary population to roughly 80 inhabitants instead of
the 160 in the earlier scenario:

?Moore suggests two ways to accomplish this. The first is to begin
with young childless couples, the way Polynesian seafaring colonists
once did. The second is to ask the space crew to postpone reproduction
until the woman is 35 to 40 years old, creating longer time gaps
between the generations. This results in a stable population of just
80 but the consequences of the increased medical risks of late
childbirth have to be considered.?


?What would be a good number to start with? An expedition of between
150 and 180 people could sustain itself at the same rate over many
generations, Moore calculates.?
?Report: Make deep space travel a family affair?

While Moore suggests that 150-180 initial inhabitants would be optimal
to insure and sustain a healthy population for more than 20 centuries
without significant inbreeding, he stated in 2002 that such a mission
could theoretically be carried out by as few as two females, taking
with them a large number of frozen embryos from Earth and the medical
knowledge and experience to implant the embryos into one another to
begin their traveling ?family?.

?In 2002, the anthropologist Dr. John Moore estimated that a
population of 150-180 would allow normal reproduction for 60-80
generations--equivalent to 2000 years. A much smaller inital
population of two female humans should be viable as long as human
embryos are available from Earth. Use of a sperm bank from Earth also
allows a smaller starting base with negligible inbreeding.?
?Space Colonization?

Of course Moore must discount certain potential problems with this
place where human emotions intervene. Issues such as infighting, the
inhabitants developing their own government and breaking away from the
Earth bound government, or self-destruction through disease or civil
war or some things that would certainly seem necessary to factor into
the mission. Having said that, Moore?s theory is obviously based in a
best case scenario and assumes that all generations over the 500 or so
year journey will remain loyal to a government and a planet they have
never visited and a cause that they did not willingly embark upon

Your question is indeed a fascinating one and one that many of us have
considered in the past. What I find to be an even more fascinating
concept however, and one that I guess I never considered before, is
that the charter group must accept the fact that they are leaving the
earth forever, never to return or to see the final destination. This
would truly be the ultimate sacrifice for science. The second issue,
which of course is not related to the breeding program at all, is that
the decedents, should they ever return to earth, would have developed
their own language during their 500 year journey for which there will
be no earthly interpreter. They will, in effect, be ?coming home? to a
planet populated by extraterrestrials with whom they have nothing in
common and cannot communicate.

?And it is entirely possible that if these humans remained in
reproductive isolation for long enough, they could evolve into another
species altogether.?
?Humans will 'sail to the stars?

You can read much more about this scientist?s theories by repeating
this Google search:

Anthropologist John Moore space

Of course you can always contact Professor Moore and get his personal
views on the subject:

Anthropology Department
University of Florida
Gainesville, FL 32611
(352) 846-0263

Below you will find that I have carefully defined my search strategy
for you in the event that you need to search for more information. By
following the same type of searches that I did you may be able to
enhance the research I have provided even further. I hope you find
that my research exceeds your expectations. If you have any questions
about my research please post a clarification request prior to rating
the answer. Otherwise, I welcome your rating and your final comments
and I look forward to working with you again in the near future. Thank
you for bringing your question to us.

Best regards;
Tutuzdad ? Google Answers Researcher


?"Magic number" for space pioneers calculated?


?Humans will 'sail to the stars?

?Report: Make deep space travel a family affair?

?The Kin Of Deep Space?

?Space Colonization?

Anthropology Department
University of Florida
Gainesville, FL 32611
(352) 846-0263



Google ://



John Moore 






Minimum number
Subject: Re: Minimum number of humans for viable space colony?
From: pinkfreud-ga on 25 Jul 2004 14:09 PDT
Speaking of mad scientists, the MadSci Network provides an excellent
response to a question very similar to yours. Here's a brief excerpt;
for more info, you may want to read the page in its entirety.

"If I wanted to send an expedition into deep space to establish a
colony, how many unrelated, fertile mating pairs (from the same ethnic
background) would be needed to form the basis of a viable colony,
assuming that they would never have contact with other humans again?

...The answer to this question depends on your initial colonists. If
they are lucky... they could get away with a very small number of
founders. In this case, luck could be enhanced by genetic screening
for individuals with a minimal number of dangerous recessive alleles.
On average, each of us is supposed to have on the order of 10-100
defective genes out of the 30,000 or so in the genome. However,
careful screening of the entire human population, or perhaps a
selective breeding program, could possibly come up with a set of
individuals with a smaller number. If you look at the islanders of
Tristan de Cunha, you can see that success is possible with a small
number (on the order of 10 each) of founding males and females, even
with disease-causing genes in the population. Similarly, the
Polynesian island of New Zealand seems to have had between 50-100
founding females, with a corresponding number of males, and
populations in eastern Polynesia may have been founded by even smaller
numbers of people."

MadSci Network: Genetics

I was not able to find detailed plans for a human breeding program. I
hope another Researcher will be able to locate that information for
Subject: Re: Minimum number of humans for viable space colony?
From: scubajim-ga on 27 Jul 2004 16:43 PDT
This is an excellent question.  Of course, the more important follow
on question is "Who would you take with you?" <grin>....  I don't
think you have to limit yourself to one race.
Subject: Re: Minimum number of humans for viable space colony?
From: digicross-ga on 06 Apr 2005 19:44 PDT
From a biblical point of view, 8 people would suffice. A father and
his three sons, along with their women. Added a couple of genetic
engineering capabilties (Hey, Noah could have been a genetic
engineer), that would do fine.

A couple would also suffice, plus a large communities of non-human communities.

Of course, if you want to have a whole complete functioning community
from the day of the launching, it might be better to start a whole
community / village (the number of people can vary much like any
village on Earth) at Earth first and then after a few years or maybe
even decades, you sent them to Mars.

It should be noted that the more people you had doesn't necessary mean
better things, since that there would be more people to manage and the
head of the community would had a difficulty if there are too many
people to manage.

In the end, it's not about genetics nor population, but how to manage
a family. It would be better to construct the community primary based
on hierarchical leadership rather than genetics nor maintaining
constant population. What one should ask is not the minimum number nor
the maximum number nor also their genetics, but instead, who are
suited to be taken.

It should be noted that humanity's root on this planet is so strong
that there might not be a participant willing to voluntary leave this
planet forever (long term maybe, but forever and voluntary?). Even if
there's a human descendant who never heard or know this planet, he or
she probably will have an instinct to come to this planet and will
conduct a pilgrimage back to his or her 'home' planet, the urge to
come back 'home' will come either conciously or sub-conciously.

Maybe in the end, humans who became extra-terrestrial colonizers might
not due so because of science and exploration, but because they are
criminals and banished from Earth because of their crimes. Much like
on how many communities in Australia and Hong Kong are founded, not
primary because of colonial reasons, but because of evictions.

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