Hello One and All,
A very good friend of mine recently asked me the following question:
What is the minimum number of people needed to create a viable human breeding population to avoid the problems of inbreeding? I like to open this question for discussion within our forum.

What follows is my answer to her. Any other opinions on this question?

This is indeed a very interesting question and the experts are, as always, giving us all sorts of different answers. For those of us interested in one day establishing a human colony in space one researcher has estimated that you would need 160 people and with some social engineering it might even be possible to reduce this to 80.

Anthropologist John Moore of the University of Florida came up with this number after studying 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.

http://answers.google.com/answers/threadview?id=378894

When the Toba super volcano in Indonesia erupted and triggered a major environmental change it has been suggested that a bottleneck of the human population occurred c. 70,000 years ago, and that the human population was reduced to c.15,000 individuals globally. It has been estimated that in sub-Saharan Africa alone the human population could have dropped at times to as low as 2,000, for perhaps as long as 100,000 years, before numbers began to expand again in the Late Stone Age.

http://en.wikipedia.org/wiki/Population_bottleneck

Other estimates suggested that the Toba catastrophe reduced the world's human population to 10,000 or even a mere 1,000 breeding pairs.

http://en.wikipedia.org/wiki/Toba_catastrophe_theory

As far as I am concerned you need a minimum if 2,000 breeding pairs to repopulate a planet like the Earth. But, yet again I may be wrong and I just plucked this answer from right out of my hat. : )

I am not really clear which of these answers are correct, In the case of eventually colonizing space I believe humans will have to resort to artificial methods (cryogenically freezing human embryos, artificial insemination and genetic engineering) to create genetic diversity.

Bye for now and best regards,

Alex

This is going to be a NEAT discussion, I hope.
I have some more questions to add to the mix. Or mabey they arejust thoughts.
The Amish and His-sed-ick Jews (or certain sects??) and some tribes in New Gunny have more than 160 people but they are having gentic problems due to their limited choices of mates. How dose that fit in? I know that the Amish (at least) keep VARY goodrecords of family trees, but they are still having gentic problems. I am going to guess that this is true for thoses jews who areVARY traditional in their relgion. Or perhaps I should say that they limit their choices of marrige partners to only thoses who are of theirview of God. (I am so sorry I am digging a real deep hole, please except my aplogies.) Thoses of the proper d-nom-ahh-nation????
Also where dose Iceland fit into this? What do their experts have to say? They keep amizing records of the whole country's g-knee-ahhh-low-g. Due to their small and contained
population, they have been able to do that.
Just wondering.
--- On Tue, 9/29/09, Alex Michael Bonnici wrote:

From: Alex Michael Bonnici
Subject: [spacesettlers] What is the minimum number of people needed to create a viable human breeding population?
To: "Spacesettlers"
Date: Tuesday, September 29, 2009, 1:06 PM

Hello One and All,
A very good friend of mine recently asked me the following question:
What is the minimum number of people needed to create a viable human breeding population to avoid the problems of inbreeding? I like to open this question for discussion within our forum.

What follows is my answer to her. Any other opinions on this question?

This is indeed a very interesting question and the experts are, as always, giving us all sorts of different answers. For those of us interested in one day establishing a human colony in space one researcher has estimated that you would need 160 people and with some social engineering it might even be possible to reduce this to 80.

Anthropologist John Moore of the University of Florida came up with this number after studying 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.

http://answers. google.com/ answers/threadvi ew?id=378894

When the Toba super volcano in Indonesia erupted and triggered a major environmental change it has been suggested that a bottleneck of the human population occurred c. 70,000 years ago, and that the human population was reduced to c.15,000 individuals globally. It has been estimated that in sub-Saharan Africa alone the human population could have dropped at times to as low as 2,000, for perhaps as long as 100,000 years, before numbers began to expand again in the Late Stone Age.

http://en.wikipedia .org/wiki/ Population_ bottleneck

Other estimates suggested that the Toba catastrophe reduced the world's human population to 10,000 or even a mere 1,000 breeding pairs.

http://en.wikipedia .org/wiki/ Toba_catastrophe _theory

As far as I am concerned you need a minimum if 2,000 breeding pairs to repopulate a planet like the Earth. But, yet again I may be wrong and I just plucked this answer from right out of my hat. : )

I am not really clear which of these answers are correct, In the case of eventually colonizing space I believe humans will have to resort to artificial methods (cryogenically freezing human embryos, artificial insemination and genetic engineering) to create genetic diversity.

Bye for now and best regards,

Alex

I know that the plan from the Seventies was to build a habitat
for ten thousand, and have that population get busy building
another, and both of those populations build one more each,
until you had eight to sixteen habitats, each containing ten
thousand people.

Man, can I write a long sentence or what!

After that, the 80 thousand to 160 thousand people would
divide their efforts between building powersats and building
more habitats, with a percentage or two dedicated to
"everything else."

I'd imagine that eighty thousand to a hundred sixty thousand
should do it, especially if they're still building more
habitats and still taking on new immigrants.

Hello, introductions first - I'm a CA by birth, recently moved from Wa to AZ, mid-40's and a lifelong fan of astronomy and sci-fi. Just joined the group.

What I've read indicates the real problem for an isolated space colony isn't genetics but culture.
Assumptions 1) what we're talking about isn't a complex of orbital/lunar factories making solar power-sats, or zero-gee alloys or pharmaceuticals to send down to Earth, or even engaged in constructing Habitats - those space workers won't be isolated in any practical sense. Only around a second's delay in communication means support from 'downside' experts is no limit, and it's only a day or a week to physically connect with the billions on the homeworld.
2) in contrast a Colony on Mars (or further out) won't have unlimited Intellectual support in a practical sense, and long term success probably depends on a very large array of complex skills, skills that are mostly more complex than any that previous generations of humans have ever needed to survive. No offense intended to any of our ancestors but the skills of shepherds, masons, coopers, brewers, and coppersmiths can't compare to the experts that will be needed by the Colony. It may be that one could identify 500 or more distinct career specialties for technicians, scientists, administrators, etc. each requiring a dedicated expert. Genetic viability should be simple in comparison, thanks to the aforementioned existing technologies.

Yes but how many different people or uniqe gentic sets are needed to keep the group going with out having to worrie about inbreeding/weak genes taking over?
This is a different question than what is needed to have a functioning high tech socioty.

--- On Tue, 10/6/09, SteveK wrote:

From: SteveK
Subject: [spacesettlers] Re: What is the minimum number of people needed to create a viable human breedi
To: spacesettlers@yahoogroups.com
Date: Tuesday, October 6, 2009, 2:47 AM

Hello, introductions first - I'm a CA by birth, recently moved from Wa to AZ, mid-40's and a lifelong fan of astronomy and sci-fi. Just joined the group.

What I've read indicates the real problem for an isolated space colony isn't genetics but culture.
Assumptions 1) what we're talking about isn't a complex of orbital/lunar factories making solar power-sats, or zero-gee alloys or pharmaceuticals to send down to Earth, or even engaged in constructing Habitats - those space workers won't be isolated in any practical sense. Only around a second's delay in communication means support from 'downside' experts is no limit, and it's only a day or a week to physically connect with the billions on the homeworld.
2) in contrast a Colony on Mars (or further out) won't have unlimited Intellectual support in a practical sense, and long term success probably depends on a very large array of complex skills, skills that are mostly more complex than any that previous generations of humans have ever needed to survive. No offense intended to any of our ancestors but the skills of shepherds, masons, coopers, brewers, and coppersmiths can't compare to the experts that will be needed by the Colony. It may be that one could identify 500 or more distinct career specialties for technicians, scientists, administrators, etc. each requiring a dedicated expert. Genetic viability should be simple in comparison, thanks to the aforementioned existing technologies.

On Tue, Oct 6, 2009 at 4:27 PM, john jones wrote:
(...)
> Yes but how many different people or uniqe gentic sets are needed to keep the group going with out having to worrie about inbreeding/weak genes taking over?
> This is a different question than what is needed to have a functioning high tech socioty.
(...)

I have seen several answers to that question, ranging from a few
hundred to many thousands of people. Based on historical and evolutive
population bottlenecks known to have occurred along Humanity's
journey, though, I am more inclined to believe in the "few thousands"
figure. For instance, according to the Toba Theory, Humanity may have
dwindled to just 1,000 breeding pairs around 70,000 years.

Bottlenecks far more severe are still possible, though with noticeable
health effects in the population. Those health effects may not be
incapacitating for the society, though. For instance, 40% of all
Ashkenazi jews living nowadays descend from just four women from 2,000
years ago. They do have a higher incidence of A LOT of diseases (some
of them very rare in other groups), but nevertheless in general they
are a long-lived and very productive population.