Populating an new planet.

[ArchWarrior]

Ok, this topic came when I and some friends was talking about space travel. And that was how many people you need minimum to form an healthy and stable population on a new world?

This question came up when someone asked what if a large spaceship full of people got separated from the rest of the fleet and had to crash land on an uncharted but habitable planet with no way of getting of the planet or making contact to rest of the fleet. How big of an base population would you need to populate the planet without having the side effects of bottlenecking and inbreeding.

Some of us said you would need base population of an few hundred at last. So, we came to an number of about 300 to 500 at lest, but there may be some problems. So an good base population would be about 1000 to 3000 people.

What do you think? How big of an base population do you need minimum to populate a new planet with enough genetic diversity to stop viruses and genetic diseases from running wild and killing off everyone in a few generations?

[Fe1ix]

I would probably say at least 100 people but the planet would have to be breathable before anything can happen.

[[Envy v.4]]

Assuming you have a planet that has every characteristic that humans need in order to live, i.e oxygen, water, food, trees, the most basic stuff, I would say simply a male and a female.
Why? Because it depends on the needs.
If they want to build an ultra modern society, then of course it would take a lot more.
But if they want to restart the race and populate a planet, no more than two is needed. Well, it's the minimum, of course.
Technically speaking we'd need a doctor, to make sure everyone's alright, and so on...

[Mister Adequate]

I don't recall for sure, but I believe that the minimum number of people for a sufficiently diverse genetic stock is 7; 4 females and 3 males. However, you'd really want at the very least a few dozen people, as not everyone will be healthy, etc. - personally I wouldn't want to start a colony with fewer than a couple thousand people.

[IronySandwich]

[Envy v.4]

Assuming you have a planet that has every characteristic that humans need in order to live, i.e oxygen, water, food, trees, the most basic stuff, I would say simply a male and a female.
Why? Because it depends on the needs.
If they want to build an ultra modern society, then of course it would take a lot more.
But if they want to restart the race and populate a planet, no more than two is needed. Well, it's the minimum, of course.
Technically speaking we'd need a doctor, to make sure everyone's alright, and so on...

It doesn't work like that. Two people does not give you a sustainable genetic population. No matter how much you tried to reproduce the species, inbreeding depression would in all likelihood kill your group off eventually. With humans, you'd need at minimum 100 or so individuals, closer to 2000 if you don't want to have to have 10-20 children each to counter the increased mortality rate.

[Golden Dysprosium]

[Envy v.4]

Assuming you have a planet that has every characteristic that humans need in order to live, i.e oxygen, water, food, trees, the most basic stuff, I would say simply a male and a female. Why? Because it depends on the needs. If they want to build an ultra modern society, then of course it would take a lot more.But if they want to restart the race and populate a planet, no more than two is needed. Well, it's the minimum, of course. Technically speaking we'd need a doctor, to make sure everyone's alright, and so on...

Yeah...that's a little too biblical for me. I'd say bare minimum would be in the double-digits, and you'd have to try and get as many children from each couple as possible.

[Radijs]

Survival has something called the "50 - 500 rule". 50 members are needed for short term survival of the species 500 for the long term survival.

All in all, if I was in charge of a colonization operation I'd send as many colonists as possible and even more 'genetic colonists'.
Those are frozen fertilized embryo's which can be carried to term by the colonists allowing for more genetic diversity without adding that much more mass.

[Darkphantom]

IronySandwich

[Envy v.4]

Assuming you have a planet that has every characteristic that humans need in order to live, i.e oxygen, water, food, trees, the most basic stuff, I would say simply a male and a female.
Why? Because it depends on the needs.
If they want to build an ultra modern society, then of course it would take a lot more.
But if they want to restart the race and populate a planet, no more than two is needed. Well, it's the minimum, of course.
Technically speaking we'd need a doctor, to make sure everyone's alright, and so on...

It doesn't work like that. Two people does not give you a sustainable genetic population. No matter how much you tried to reproduce the species, inbreeding depression would in all likelihood kill your group off eventually. With humans, you'd need at minimum 100 or so individuals, closer to 2000 if you don't want to have to have 10-20 children each to counter the increased mortality rate.

I think the technical number with human genome and rates of genetic drift was 14-20, Predominantly female, Not only that you would require planned family marriages for the first 7 generations or so to ensure mixing up of the bloodlines. This is because of the way our population grows, We have a Type I Survivor ship pattern where we give birth to few young and have high parental investment.

If your colonising a new planet mortality would be lower than you think assuming there aren't any pathogens that can initially infect humans least due to alien biochemistry.

[Radijs]

Darkphantom

IronySandwich

If your colonising a new planet mortality would be lower than you think assuming there aren't any pathogens that can initially infect humans least due to alien biochemistry.

But that situation isn't really likely to last long is it? Microbes can adapt very quickly. Several thousand generations if I recall correctly. So in a few weeks or months you would have alien bacteria who could infect the colonists.

[Golden Dysprosium]

Radijs

But that situation isn't really likely to last long is it? Microbes can adapt very quickly. Several thousand generations if I recall correctly. So in a few weeks or months you would have alien bacteria who could infect the colonists.

Not to mention the bacteria that comes from the colonists, and possibly even the food. Don't forget, your body is full of bacteria.

[logan the god of candy]

to prevent inbreeding, and allowing for hunting, i would suggest 5 male/female sets of young adults. that's supposing you aren't in a severe desert climate... lol.

[DorianBlack]

Some inbreeding isn't a problem as long as there are no carriers of recessive alleles for severely detrimental traits. The minimum is probably around 10, though of course, the more, the better.

[Golden Dysprosium]

DorianBlack

Some inbreeding isn't a problem as long as there are no carriers of recessive alleles for severely detrimental traits. The minimum is probably around 10, though of course, the more, the better.

You might be able to have carriers, but you'd have to carefully match them up with people whose traits show up as dominant alleles. Don't foget the chances of genetic mutation amongst individuals.
Inbreeding could result in a far higher phenotypic expression of deleterious recessive genes within a population . As a result, first-generation inbred individuals are more likely to show physical/health defects, including:
reduced fertility both in litter size and sperm viability
increased genetic disorders
fluctuating facial asymmetry
lower birth rate
higher infant mortality
slower growth rate
smaller adult size
loss of immune system function.
Natural selection works to remove individuals who acquire the above types of traits from the gene pool. Therefore, many more individuals in the first generation of inbreeding will never live to reproduce. Over time, with isolation such as a population bottleneck caused by purposeful (assortative) breeding or natural environmental stresses, the deleterious inherited traits are culled.

[Damnati]

Source was the History Chanel "Monster Quest" or monster search, whatever that show is. It was the episode about Champ, is Lake Champlain.

The biologist on the show had said the minimum population that could survive is about 550 organisms. Less than that, and it's just not possible. Even going that low is nearly impossible, and you're likely to die off due to inbreeding, disease, attack, too low fo a birth rate, and so on.

Now, to have a healthy population (avoiding incest, ability to survive disease, and so forth), you need at least twice as many. And to have a stable population, you need three times as many. Though the ideal minimum was about 2500 I believe, and the farther under that you go, the more problems you'll have. The 1000 is a minimum to be healthy. 1500 is a minimum to be stable. You ideally want more than the minimums.


Keep in mind, however, this is an alien planet. If it's more evolved than we are (say life has been evolving for half a million years longer than on Earth), it's likely our bodies will be incapable of fighting off the natural diseases there. And even if it's less evolved, the diseases evolved on different evolutionary tracts. Meaning we'll have very few natural immunities to everything on the planet, and will be allergic to a lot. We wont know what food and animals we could eat or can't eat, what will be good or bad for us, and what can or can't kill us. So in this instance, we'll need a lot more than just the safe 2000 people, because we'll be living in a, comparatively, much more hostile environment. Under those conditions, I would want at least ten thousand people or so. And even then, depending on the native diseases, there's a good chance we wont survive. Point in case, a similar idea to "War of the Worlds," were simple diseases commonly found in water, that we're naturally immune to, killed the far more powerful aliens.

[CommandoDude]

Not even triple digits should be able to host a population growth to a few billion, assuming this new planet would be Earth like.