I know the Mars One project is pretty much a laughingstock here at the SDMB.
Don’t get me wrong, I don’t consider it any more realistic than anyone else here. I’m merely interested in this hypothetical:
Assuming a safe happy set up of a colony on Mars …
Assuming still the no possible return for the colonists …
And, assuming it is treated as a priority to set up a growable population for the colony …
(assume also that all colonists are philosophically committed to this goal, let’s keep this hypothetical from getting rapey)
What would have to be the minimum number of colonists and what should the ratio be for men to women in order to avoid inbreeding?
Every time I read anything about the Mars One project they’ve always got an even 50/50 split of men and women. That seems obviously wrong.
50 men + 50 women = 50 possible births in a year, whereas 1 man + 99 women = 99 possible births …but they’d all be half-siblings, so that’s wrong as well.
So, what would the minimum number of colonists have to be and what should the ratio be?
According to the experts ( see “Doctor Strangelove”) the ideal ratio to repopulate the world would be about two dozen men (enough to fit in the War Room) and a ratio of 10 women per man. The women, of course, will have to be young and healthy and have a very desirable appearance to encourage breeding.
(Ok, ok, they actually suggested several hundred thousand people in the mines…)
To be fair, a small population is not that big an impediment. No records exist, but I’m guessing the entire population of Easter Island (possibly several tens of thousands at its heyday) probably came from a single flotilla of large canoes. Many cultures allow cousins to marry.
Have you ever taken care of a baby? It’s a lot of work. Expecting 99 women to pump out a baby every year, all while doing every bit of work to build the colony and provide food, shelter, heat, oxygen, water for themselves and hundreds of babies and children is simply laughable.
The calculation should be: how much work will it take the average person to keep themselves alive on Mars? If you work like a dog keeping the hydroponics going, the air filters cleaned, the sewage digester operating, the kitchens, the machine shop, the EVERYTHING, how much spare time do you have available to care for a baby? An hour a day? If you have an hour a day that means it takes 24 colonists to support one baby.
It’s going to take a lot of effort to survive on Mars. More effort than most people are capable of. They’re not going to have much time to raise kids, because each child takes a decade of work before they’re able to even minimally contribute to survival.
If the air was breatheable, if the water was flowing out of streams, if the temperature was survivable, if there was food, if there was shelter, if robots provided all the material goods needed, then fine, send 99 women and keep them continuously pregnant since they just need to lounge around being human incubators. In real life people have to work for a living, and they have to work taking care of their babies and children, and they have to work teaching their older children the skill they will need to survive. Even in a magical place where food literally grows out of the ground and water literally pours out of a hole in the ground, and air literally blows past your face, like Earth.
That’s why the good Lord invented division of labor. Even granted that each person has one free hour per day, that means that 1/24 colonists will specialize as nannies who can supervise a greater number of children than 1 each.
2:1 men:women, divided into 1/3 gay couples and 2/3 straight couples
My reasoning.
The number 1 problem the colonists are going to face is the physical labour involved in keeping themselves alive. Growing the colony is, comparatively, not an important task. Replacing the colony members is an important but non-urgent task. Men have an advantage on the physical labour front, hence more men at the start.
Number 2 problem is a small isolated group of people who may go nucking futz with the sheer grind of existence. Hence, pair everyone up at the start. Affairs and sexual jealousy are a big danger - having a significant proportion of the population that you can trust never to be involved in any one couple’s relationship drama will at least help to alleviate that.
Maintaining and slightly increasing the population is number 3 on the list of issues. With this balance, a target of 4 surviving kids per woman, which is pretty reasonable for a frontier colony, should achieve that.
I did lay out a Mars Colony scenario in the OP, so discussion of the practical concerns is appropriate, welcome, and interesting. I think the practical concerns will eventually lead off into IMHO territory in which case perhaps a Mod will decide to change forums.
While we’re still in GQ, I’m more concerned about the biology of it all.
I was going to suggest a 1:1 ratio, for the purpose of maintaining stable relationships, but as Aspidistra has just pointed out, that’s not the only option. And there would seem to be some real advantages to a significant number of gay couples in the mix. I guess I’m more old-fashioned than I realize.
Now that that’s brought up, though: Most of the work in building a Mars colony is not going to be muscle work. For anything really heavy, we’d have machinery, so the humans are mostly needed for operating and maintaining the machines. Upper body strength is the only real advantage that men have, while women also have the advantage that they can get pregnant. Even if it’s not the first priority, it is on the list somewhere, and I think that that gives women the edge. So I think we’d also want to have some lesbian couples, together with their choice of frozen sperm.
Of course, any plan that calls for a certain percentage of the colonists to be homosexual is going to be a complete political nonstarter in the current climate, but then, this is a Mars trip we’re talking about. It’s already politically impossible, anyway.
Oh, yeah, and there is another advantage in having at or close-to a 1:1 ratio too. Minimises cultural disconnect between the original colonists and the generation they’re bringing up.
It’s going to be one mother of a generation gap anyway, seeing as I suspect there would be nobody under - what - 20? 25? (how long does it take to get there anyway?) at landing, and no-one’s going to be popping out any kids for at least the first 2 or 3 years, I should think. So the first kids would grow up around a bunch of oldish adults and no adolescent role-models. Bound to be some psychological issues there.
By that criteria, by the time we can reasonably set up a viable colony on Mars, it’s just as likely that we’ll have artificial wombs that take egg and a sperm and develop the baby in ideal conditions. Point in fact, that might be necessary because, due to the lower gravity, either we’ll genetically modify the babies to be better suited to Mars’ gravity - which might make them non-viable in a regular human host - or we don’t genetically modify them, in which case they need to be kept under Earth’s gravity during development, and it’s more economic to set up small, artificial wombs in a centrifuge than it is to sideline full grown women for 9 months and build a giant centrifuge for them to live in.
“Growable” is not necessarily achieving maximal growth rate.
You do need to have some reasonable guess of what, under Martian colony conditions, mortality rates are likely to be, especially during childbirth and in the childhood period, in order to estimate what the fecundity per woman we should be aiming for to grow at the rate desired for a first generation. And have to account that some germ brought along is able to mutate at some point and cause an epidemic.
I would want enough initial colonists to set up several separate “villages” with limited direct contact in order to minimize the risk that such an infectious event or even untoward mechanical event could wipe out the whole venture.
How many individuals working full time does each village require for adequate function? Multiply that by the number of villages required to feel the risk is sufficiently reduced. Note that each village can specialize in some aspect to some degree but any single one should be able to exist independently as well.
Psychological health is vital. Given that colonists are coming from cultures that are primarily monogamous I would think that replicating that would be advisable.
All should be screened for at least known recessive genes, and even those of unknown significance should have reproduction regulated to reduce risks. Yes a wide variety of screened sperm can be brought along and potentially donor ova as well. Given that, and that Norfolk Island’s current population mostly hails from 17 individuals without horrible consequence, I think the numbers required to run the operation as described above would be more than sufficient to avoid too much risk from inbreeding.
If sperm and ova could be kept viable for multiple generations I would consider that a certain fraction of each family utilize a different screened donor from that pool in multiple generations to increase the genetic diversity.
The other thing is, thinking specifically about the Mars case, they probably don’t actually care all that much whether genes are lost within a generation or two of breeding. In 30 years the colony would either be dead, or accepting visitors. Sending a ship to an existing established viable colony is so much less of a task than setting up the colony in the first place that there’s no way, absent nuclear holocaust, that they’d stay isolated forever.
It almost doesn’t matter if they have kids at all, apart from to prove they can.
I couldn’t resist that scene from " Doctor Strangelove", regarding the post nuclear war “mineshaft gap”. Dr. Strangelove":We will construct shelters in deep mineshafts…a ratio of 12 women to each man would be the most favorable one"…or something like that.
Really. life on Mars would be just like living in a maximum security prison, with the added possibility of asphyxiation.
Avoiding genetic diseases that arise from inbreeding depends on the genetic makeup of the individuals and the number of dangerous recessive genes in their DNA. Some families can take a lot of cousin marriage, some not.
I wonder if we can learn anything from isolated island communities like Pitcairn?
Pitcairn Island started with 15 men and 11 women (and a baby) 9 European men, mostly drunken working class sailors, and 6 Polynesian men. What could possibly go wrong?
IIRC most of the men killed each other or drank themselves to death within a few years. Thirty years later only one or two of the original men were still alive. But genetic issues? Presumably the original pool was varied enough that the problems did not manifest in the first few generations, if at all. The major problem was societal, much of the community fell apart about 10 years ago over allegations that sexual exploitation of younger girls was rampant.
Men can build more shit than women can. Men with power tools can build more shit than women with power tools can. Making babies is a low priority until you can feed and house them at the very least so choosing the sex balance to maximise the birthrate is just stupid as is assuming that a man is just a woman with more muscles and no uterus. A 50-50 gender balance seems to work well for humans in general so why bother to change it? And it completely escapes me where anyone gets the idea that gay people wouldn’t be causing relationship drama.
