Founding An Inbreeding-Free Space Colony

Founding An Inbreeding-Free Space Colony

SciShow is supported by 23andMe. Whether it’s SpaceX or Lockheed Martin or
NASA, eventually someone’s going to start sending people to Mars. And when that happens, we might decide to
set up a colony there, too. People could be born, raised, have their own
families, and die without ever setting foot on Earth. Sending people across the void of space to
a desolate planet is hard enough, but founding a remote colony comes with its own special
challenge: low genetic diversity. If we’re going to create new societies on
other planets, we need to know how many people to send to avoid the problems that come from
inbreeding. Whenever a subset of people goes off and starts
their own society, they’re going to be less genetically diverse than the much bigger population
they came from. That loss in diversity is known as the Founder
Effect. The differences can be amplified over generations,
especially if the new population is small. The smaller the population, the harder it
is to find someone to have babies with that you’re not related to, so you end up with
a lot of inbreeding. It all depends on which founders produce how
many offspring, and which alleles, or variations of a particular gene, they happen to pass
on. Some traits can completely disappear from
the gene pool, and rare diseases can become super common. That’s happened before. The Amish in Pennsylvania, for example, are
much more likely than other Americans to have Ellis-van Creveld syndrome, a type of dwarfism,
because one of their founders carried the allele for it. And the South African Afrikaner community,
which was started by a small group of predominantly Dutch settlers in the 17th century, has a
higher frequency of Huntington’s disease. To completely avoid the consequences of inbreeding,
a founding group needs to have enough people so that, genetically speaking, it’s basically
as diverse as the original group. And it has to be able maintain that diversity
over time. In population genetics theory, that magic
number is known as the effective population size. It’s a really broad estimate that varies
by species, and is based on things like how often random genetic mutations happen, which
members of the population mate, and how many kids everyone has. For humans, the effective population size
is thought to be at least several thousand, if not 10-20 thousand. But the more people we have to send to start
our space colony, the harder and more expensive it’ll be. So scientists have tried to calculate the
bare minimum number of people we’d need, and they’ve come up with a few different
estimates — along with a couple of other strategies that could help. In 2002, an anthropologist named John Moore
tried to calculate the population you’d need for a 200-year interstellar mission to
colonize a hypothetical Earth 2.0. Using a computer program based on the reproductive
behavior of actual pre-industrial communities, he simulated different scenarios to see what
would happen to the population over time. He found that, if you choose pairings and
make other reproductive decisions really carefully, you’d only need 75-90 young couples to start
a colony. So, less than 200 people in total. But other anthropologists have argued that
such a small number would only work if their descendents were able to make babies with
new humans at the end of their journey. Which could happen—I mean, assuming Earth
hasn’t suffered some sort of armageddon, there’s no reason we couldn’t send another
mission to Mars in a century or two, if not much sooner. Or the colonizers could pack a collection
of frozen sperm and eggs from people who never actually leave Earth, allowing them to mix
in new genes over time. Another issue with Moore’s estimate is that
it’s only enough under the most ideal conditions. For one thing, it doesn’t leave any wiggle
room for disasters that kill off a significant percentage of the population. It also doesn’t take into account the fact
that small pre-industrial groups occasionally interbred with neighboring communities. That means the actual number of people you’d
need to maintain a healthy population might be much higher. In a 2014 paper published in Acta Astronautica,
one researcher estimated that you’d really need somewhere between 14,000 and 44,000 people. If we followed that advice, our Martian colony
might be sort of like Iceland. Iceland was founded around 1100 years ago
by about 10,000 people. Thanks to the Founder Effect, the country’s
modern population of about 300,000 is one of the least genetically diverse in all of
Europe. So Icelanders keep meticulous genealogical
records. There’s even an online genetic database
that acts like one big family tree, with information on 95% of people born in the past 3 centuries. If you’re in it, you can see how anyone
else in the database is related to you. And it’s more than just an incest-prevention
tool — the database has also helped identify genes associated with certain diseases, like
Alzheimer’s and cancer. So, thanks, Iceland. If we want to colonize another planet, a similar
database to keep track of things would probably come in handy. And so might those sperm and egg vials. But before we worry about that, we should
probably focus our efforts on sending any number of people to Mars safely. It might be a while before we colonize Mars,
but you can learn about your genetic ancestry RIGHT NOW by checking out 23andMe, a service
that lets you learn where your ancestors originated and how your DNA affects things like your
facial features or your sleep quality! The holidays are coming up too, which means
you’re probably going to be spending a lot of time with family. The information you get from 23andMe can make
for some fascinating dinner conversation, like I found out that even though I’m pretty
sure my ancestors came from southern China, their DNA is categorized more as southeast
Asian than as Chinese. Good luck explaining that one Uncle Joe… I don’t have an Uncle Joe. And 23andMe is super easy to do: You just spit in the
provided tube, send it in, and in 6-8 weeks you get your results online and can dig through
a lot of cool information. There’s even a Thanksgiving sale going on
right now, through November 23 so head on over to and check out
their Thanksgiving Family Offer today!

Comments (100)

  1. Can't you just have low genetic diversity with inbreeding if you did in-vitro fertilization? Just inbreeding out traits? I know that is gross, but if people had the facilities and removed the social stigma it could work. Granted you would probably have to destroy a whole lot of technically viable embryos to allow for genetic drift. Sounds better than extinction, I suppose.

  2. Make sure nobody decides to answer any distress calls, and then send a landing party full of idiots.

  3. An embryo transfer would solve that problem!

  4. I think you could get away with a relatively small group, you'd just need to send another group within a generation. Even if it takes longer than that to reach the destination, you could have two or three voyagers occurring one after the other, offset by 15 to 20 years, each time improving the genetic diversity while also cutting the cost of each individual journey and spreading that cost out over decades. This would have the added benefit of also delivering extra supplies with each group.

    On the downside, if the overall journey is greater than a generation or two, then the follow-up groups would have no idea what to really expect and whether or not those sent before them had survived to build a colony to arrive at.

  5. Genetic engineering. Haven't watched the video yet, but biotechnology. Just change the genes.

  6. Thinking about old world problems for new world situations. By the time we start an off world colony we could probably modify genetic babies and fix issues caused by inbreeding. Heck we might not even reproduce the classic way.. by the time we start that colony inbreeding shouldn't be a major issue.

  7. Iceland is in europe like greenland is too right?

  8. That explains why trailer park people have that look.

  9. I guess weโ€™ll cross that bridge when we get there?……letโ€™s get to mars first

  10. Yay it's Stefan! ๐Ÿ˜€

  11. They should be more worried of infertility than inbreeding.

  12. Easy: send them up with a big bag of mixed sperm.

  13. OH NO! I was supposed to sPit in that vial? I guess I read that wrong. ๐Ÿ˜ฌ

  14. 23 and me should pay YOU for your genetic information since they will sell it over and over and over for researchers, the government, or whoever has enough money to get what they want. Selling your genetic information is a bad idea unless you have sound proof that they will destroy what you gave them and all the data alone with it.

  15. Can u tell that to Islam? It's 'god's way' to marry your first cousin. Causes violent irrational rage and mental retardation in just one generation. It also piles up. The UK has such a problem they launched a public health awareness campaign to pretty much fail. Maybe so many ppl would stop trying to blow themselves and other ppl up. This is a major problem and it's all our problem as it's Earth's gene pool.

  16. That was really interesting.ย  Also, I haven't watched scishow in a while… really like this new guy and his mature handing of the subject.

  17. Iโ€™ve heard estimates as high as 500,000 being required to maintain genetic diversity. But if only several tens of thousands are required, is it possible such a colony could survive starting with 200,000?

  18. Lets have sex… for science

  19. The guy's nose is pointing the other way of his face…

  20. why don't salmon have a problem with inbreeding

  21. 23 and me is a insurance trick so that the companies can jack up rates based on your genetics.

  22. I would think that they would have relationships but have a complex web showing who will โ€œmateโ€ with who so you can love one person but have to breed with someone else.

  23. In case it doesn't work pack a good supply of banjos.

  24. It's why we have to have a large genetic pool. In the world. We need each other for keeping up. Generations

  25. Ummm, 23andme? I pay to have my DNA stored in a database and to be later exploited by insurance companies ๐Ÿค”๐Ÿค”๐Ÿค” no thank you

  26. That means no chinese in space

  27. I thought the title said we found one ๐Ÿ˜‚๐Ÿ˜‚

  28. 23andMe seems completely useless for non-white people.

  29. Greetings from Iceland, and, you're welcome ๐Ÿ™

  30. Now that's something they can test in Tuskegee.

  31. Damn, people are bad enough as it is. Some can't handle humans from another country, let alone another planet. Yeah, we're gonna end up with some serious problems….

  32. didn't bring up a very big problem in these scenarios … cheating on your spouse. there have been studies that show that about10% of children are told the wrong guy is their dad. a 10% shift to unknown parentage would be cataclysmic in such a small population.

  33. Given current technology, I think it is already kind of silly to worry about this. As mentioned in the video, it wouldn't be hard to send extra genetic material.

  34. Hypothesis- Why not send 100-ish young couples, wait 50 or so years, send another wave of 200 people, wait 50 or so years, then maybe send a larger wave of 500 people. Over time, space travel will be more streamlined and efficient, ergo inexpensive, and perhaps the Mars colony will start finding/making things of value there that can contribute to the overall goal of colonizing mars. Eventually you'd have a large enough size on Mars that it'd work out just fine. Say, within 500 years, you maybe be able to send groups of 1000+ humans every 20-50 years, and that's not accounting for when recreational travel between earth and the colony become possible, and interbreeding between the two planets happens. (Sidenote- Planet to planet child support would be one hell of an issue!)

  35. 23andme dont work in Europe btw

  36. The problem with these small scale systems is it is essentially forced breeding. The starting crew might all agree to pre-determined selections, but anyone born on the ship will be along for the ride, I wonder if these studies have taken that into account, or they just dont care…

  37. In hinduism it is said to marry according to Gautra(ancestry catagory )…people from same gautra are automatically considered as brothers and sisters…so everyone has to maintain diversity by marrying people from different gautra…

  38. I was a little confused by why Mars is the example here. Other star systems, sure, but Mars isn't that far away.

  39. I thought you were Filipino

  40. I used to live in Utah and you can see the effects of having to small a gene pool. Thereโ€™s a reason they spell moron with two mโ€™s lol (Mormon)

  41. That's one question I always had about people living in an island, how do you not eventually interbreed with your family members at some point in time? Like you'd have to get newer people from the outside to not do that. I think.

  42. Didnt 23andme give back false information to stump racists?

  43. I just had to watch a roundup commercial before your video. You know that you can block certain companies to display commercials before your videos right?

  44. I'm my own grandpa.

  45. In my Victatorship if you aint making disease or unwanted babies sex is healthy and fun. Would not hurt young people to be good at it atall.

  46. Moon first, Mars later.

  47. All the "racial purity" jackasses are inbred themselves…

  48. I'm not griping here, Scishow, but i'm thinking you overshot this by a few hundred kilos. If we'd be setting up a colony on, say, Mars it wouldn't be a once off "there you go, now breed". We'd likely have back and forth travel quite a bit. Think back to the colonial age.

  49. Just wondering about 23 and me. I am under the impression that all humans came from one original group, so what's with all this highly discriminatory identification with the places where human migrated to?

  50. Inbreeding is gross, unless everybody's sexy.

  51. Tbh space travel for us is exactly like across sea travel for those hundreds of years ago, information travels slow (radio signals and slow traveling letters) and both are scarcely explored and is scary to travel to. We will be able to communicate in seconds in a few hundred years across planets, and then after we do this, we will have the same situation with travelling to other solar systems, and then galaxies.

  52. Jebediah Springfield: People, our search is over! On this site we shall build a new Martian colony where we can worship freely, govern justly, and grow vast fields of hemp for making rope and blankets.

    Shelbyville Manhattan: Yes! And marry our cousins.

    Jebediah Springfield: I was- wha… what are you talking about, Shelbyville? Why would we want to marry our cousins?

    Shelbyville Manhattan: Because they're so attractive. I… I thought that was the whole point of this journey.

    Jebediah Springfield: Absolutely not!

    Shelbyville Manhattan: I tell you, I won't live in a Martian colony that robs men of the right to marry their cousins!

  53. Welp … Founders law basacly gerenties that some ppls grand pappy could be grandma's father XD (that's some chilling news)

  54. Hey, hi๐Ÿ™‹๐Ÿฝโ€โ™‚๏ธ๐Ÿ™‹๐Ÿฝโ€โ™‚๏ธ๐Ÿ™‹๐Ÿฝโ€โ™‚๏ธ๐Ÿ™‹๐Ÿฝโ€โ™‚๏ธ what about introducing crisper to the mix? Will it make any difference?

  55. I would like to see White people colonizing mars soon.

  56. sed frozen egg like the movie interstellar do LOL

  57. I'll have you know that Cleopatra VII was one of the best educated women of her time (in a era that educating women was looked down upon in every civilization outside Egypt) and severely inbred and Albert Einstein married his 1st cousin

  58. Easiest way is just to send a diverse couple hundred thousand eggs and sperm with them. by the time we actually send someone tomorrow is, the artificial wombs will be up and running.

  59. Go to moon first so we can see what we need to do at a closer location

  60. There are 153 mitochondrial haplogroups on earth. The true minimum number of people for a single colony should be approximately 306 people, assuming each has been screened for all known genetic illness markers and confirmation of fertility. The given population would have the same diversity as the parent group (minus defects) and would stay healthy for much longer if isolated. A regulated breeding program would need to be instituted, implementing embryonic filtration (a technique used in British fertility clinics to eliminated BRCA2 which is an inheritor for breast cancer) until the population was large enough on mars to allow for uncontrolled breeding.

  61. We will call the colony New West Virginia.

  62. Hang on. Wasn't there a population bottleneck in our history that reduced human population to a few thousand. I remember watching a program about it on Nat Geo.

  63. Or genetically modify the brother and sister. So that they can smash… That would be hot, and it would work.

  64. Lgbt peeps will call this bigotry ๐Ÿ˜‚

  65. Space colonizations are not for LGBTS, its bound to fail.

  66. Space colonizations are not for LGBTS, its bound to fail.

  67. I donโ€™t trust 23 and me

  68. FFS Just send frozen semen and embryos.

  69. The problem with sending only a few hundred people is that after a few generations you would only have a few people who could marry without inbreeding, which would be like arranged marriages, which may be inhumane for a space company to force upon people.

  70. Mars is way too harsh to colonize the sad is literally toxic

  71. Flights to Mars, anyone? Live there for a few years, and send eggs/sperm to earth..and both

  72. the 90 couples theory I think works out well for a first wave of colonists for mars, the moon, or a orbiting colony. the biggest issue will be limiting population growth to not out grow their confined space and limited resources. but step one is just getting there and setting up base camp 1.

  73. Small population of women 90%+. All women of childbearing age. Have a diverse set of embryos & a sperm bank each woman has 4 children from the embryo bank. Rather then send couples up there.

  74. New techs centered on AI, like new energies & materials, IoT & big data processing, new medicine & education

    ( including gene manipulation ) are expected to realize the sustainability of human civilization on Earth.

    I hope these โ€œ sustainable โ€œ techs will also be utilized in the age of โ€œ (full-scale development of ) space โ€œ techs ๐Ÿ’–. ๏ผ

  75. Just make sure they pack CRISPR CAS-9 and everything will be fine! And if it isn't, just fix it ๐Ÿ˜‰

  76. Hehe, I love how they dance around the fact that the lowest end estimates basically mean embracing multiple breeding partners and strictly abiding by plans that say you will have a kid with persons A, B, and C… but absolutely none with D or F. Of course, this could all just as easily happen in a lab rather than a bedroom, but still, having to embrace a hard split between choice monogamy and procreation was apparently weird enough they didn't want to be explicit about it.

    Also, the customers of businesses like 23AndMe are actually providing them with the raw material for their real businesses, private research and data mining/trading… and paying for the privilege rather than being paid for it. Don't do it unless you have a really compelling reason, and even then, shop around for a better privacy policy if at all possible.

  77. It's not incest if u say no chromo

    – gigguk 2019

  78. Why would need inbreed
    Use crispr and make diffrent gene

  79. This remind me of Kill Zone and the Helghast

  80. Dont forget the many harmful effects of low gravity. I think we are at least 300 years away from creating gravity.

  81. Who will be the 1st colonizers?
    The super rich 1% ers? Thats a low gene pool and high concentration of a family names. How many monarchs in european history had genetic illness due to ideas of pure blood. Unless there's a way to make it feasible to have upper middle class. Even then wouldn't colonizing have at least to some degree do to America what magnet and private scools do to public schools. Decrease the median intelligence and income for the district. In this case it would be earth or America.

  82. Eurika I've got it!!
    Dont send PEOPLE TO SPACE!!!
    send gentics
    Its small enough to ship them in bulk. Just send the surrogate women. Its sucks but it would GREATLY save weight limitations. The weight of sperm/egg vs any aged human. Likewise we should send lots of dirt and seeds. NOT the sprouted plants them selves. What about marine life? Im gonna miss the dolphins sharks and fish. Lol catfish would become the new lobster. You know the cheap fish anyone could buy. lol.

  83. There is no need to go to mars . In fact NASA should be removed from control of our government . If privet people want to spend the money to do such things Let them. I really mean let them. No one should get in their way. But we shouldn't make our people do it. But having it paid for by taxes . We can't afford it, and we don't need it.

  84. Simple! You just need to bring along the technology to engineer the genome and create some beautiful, healthy designer babies ๐Ÿ‘ถ ๐Ÿ‘๐Ÿ˜Š

  85. Alabama sweats perfidiously

  86. I do not like them Serm-I-Erm, I do not like cloned eggs and sperm

  87. Easy problem to solve with just 3 rules:

    1. Send 2 people from each country.
    2. You may not mate with someone from the same country as you.
    3. You may have no more than one offspring per mate.

  88. Alabama has left the chat

  89. One thing about iceland is all or maybe almost all 10K founders were european. With a space colony, one can maximize initial diversity by selecting from all across the globe.

  90. Is this how matchmaking became a thing? If they started with an organized matchmaking program then it could be mitigated.

  91. Send two siblings.

  92. None of that matters, it still will come down to fighting the female's nature of being with the top alpha guy. Most the women will avoid 80% of the guys to be with the top 20%.

  93. I bet you have an Uncle Zhao tho lol

  94. There exist 153 individual haplogroups in mitochondrial DNA. To provide sufficient diversity, you would need to have one couple for each haplogroup to mirror the diversity of the current population of earth. Each candidate to represent a haploid group must be put through an intensive genetic screening to identify problematic genes so that non-genetic illnesses would not be carried forward into the budding colony. This should theoretically prevent any particular group from exhibiting a specific genetic defect.

    If youโ€™re not afraid of exploring the gray area of morality and gene editing:
    On top of selecting the correct group of diverse individuals you could introduce some enhanced gene selection using modified adult stem cells to correct for the environment the colonists would be living in. Based on my own personal research, modifying the adult stem cells located within the five bones or other large bone marrow collection sites could potentially rewrite the genetic code of full-grown adult and grant them benefits of the improved code. You could also potentially modify the germ line of the volunteers so that any genetic enhancements made to these original colonists would be guaranteed to be passed along to their offspring. There are quite a few beneficial mutations found within the human population which could be added to a potential colonists germline to give the colony the best possible chance of success.

  95. It sounds like all of these calculations assume monogamous relationships. Is that true? If so, how do estimates change if you assume, for instance, that every woman bears three children, each with a different father?

  96. Send only females and a lot of stored sperm from many different males. Sterilize any males that are born to ensure females use the stored sperm when they get pregnant.


  98. I will remain extremely skeptical concerning Mars 'colonization' until we have good data on long-term exposure to Mars gravity. Let's add an Orbital Gravity Simulation Test Lab to the ISS or successor because it's definitely preferable to test this sort of thing near Earth instead of learning the hard way on Mars.

Comment here