What number is needed to keep genetic diversity.

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gaby
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What number is needed to keep genetic diversity.

Unread post by gaby »

Hi,I like to known what number of Humans is needed,to keep genetic diversity and avoid problems with inbreeding.

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Re: What number is needed to keep genetic diversity.

Unread post by drewkitty ~..~ »

50 years ago the minimum number of indeviduals was thought to be about 128.
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Re: What number is needed to keep genetic diversity.

Unread post by Killer Cyborg »

If you're unconcerned with infant mortality, it doesn't really matter.
All the defects die off within a generation or two.
(Especially if you weed them out yourself).

Remember, inbreeding doesn't cause mutation- it simply brings forth recessive traits.
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Re: What number is needed to keep genetic diversity.

Unread post by Nekira Sudacne »

The question depends a lot on if you stick to monogamous mating or are practice multiple mates per person.

the social dynamic of the group will say a lot about about the number. Not simply for how many children will be in each generation, or how many mates a male or female can have, but how reckless and violent they are (leading to more death, requiring a larger population to maintain minimum viability over time), how much space is alloted them (trying minimize space leads to friction, which can again lead to accidental or deliberate death). and more importantly, how long they can stay as a unit without breaking off into subgroups.
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Re: What number is needed to keep genetic diversity.

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The christians believe we all descended from Adam and Eve.
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Witchcraft
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Re: What number is needed to keep genetic diversity.

Unread post by Witchcraft »

and that's about as genetically diverse as it gets...
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Re: What number is needed to keep genetic diversity.

Unread post by drewkitty ~..~ »

say652 wrote:The christians believe we all descended from Adam and Eve.

More like "Those who put their trust in God's word know that humans as we know us started with Adam and Eve."
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Re: What number is needed to keep genetic diversity.

Unread post by glitterboy2098 »

basic rule of thumb is 50/500

minimum 50 unrelated individuals for genetic survival, or 500 including related individuals. more is always better though.

below that you run the risk of long term genetic issues due to inbreeding. (Genetic diversity being fairly important)
not so much from mutation/deformities, than from susceptibility to illness and environmental changes. (look at how medically fragile most purebreed pets are.. same issue, since purebreeds generally all stem from a very small initial population)
this is why Cheetahs have been so hard hit in recent times.. around the end of the ice age it is believed their population was reduced down to about a dozen individuals. as a result, every cheetah alive today stems from a heavily inbred initial population.. they've adapted to it, and some of their reproductive adaptions to increase relative diversity within a litter probably is why they made it through the mass extinction, but it has left them vulnerable to changes in climate and to sickness.
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Re: What number is needed to keep genetic diversity.

Unread post by arouetta »

70,000 years ago humans were nearly wiped out. Studies vary, but one source said it was possible that there were only 40 breeding pairs of humans left (admittedly, that's the lowest count of the various studies and that's not counting those too young).

Considering how well we've done at coming back and taking over the world, for a game you could argue 80 people, evenly divided between male and female.
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Re: What number is needed to keep genetic diversity.

Unread post by Nekira Sudacne »

arouetta wrote:70,000 years ago humans were nearly wiped out. Studies vary, but one source said it was possible that there were only 40 breeding pairs of humans left (admittedly, that's the lowest count of the various studies and that's not counting those too young).

Considering how well we've done at coming back and taking over the world, for a game you could argue 80 people, evenly divided between male and female.


i always questioned that conclusion. they did conclude that all living humans can trace mitocondrial DNA to only 40 sources along the female line, but that dosn't suggest only 40 females were alive then, only that of however many females there were, eventually those decendants interbred amoung only those 40 lines.

Granted, that still suggests no more than a few hundred fertile women.
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