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How Many People Does It Take To Colonize Another Star System?
Hugh Pickens DOT Com writes: "The nearest star systems — such as our nearest neighbor, Proxima Centauri, which is 4.2 light-years from home — are so far away, reaching them would require a generational starship. Entire generations of people would be born, live, and die before the ship reached its destination. This brings up the question of how many people you need to send on a hypothetical interstellar mission to sustain sufficient genetic diversity. Anthropologist Cameron Smith has calculated how many people would be required to maintain genetic diversity and secure the success of the endeavor. William Gardner-O'Kearney helped Smith build the MATLAB simulations to calculate how many different scenarios would play out during interstellar travel and ran some simulations specially to show why the success of an interstellar mission depends crucially on the starting population size. Gardner-O'Kearny calculated each population's possible trajectory over 300 years, or 30 generations. Because there are a lot of random variables to consider, he calculated the trajectory of each population 10 times, then averaged the results.
A population of 150 people, proposed by John Moore in 2002, is not nearly high enough to maintain genetic variation. Over many generations, inbreeding leads to the loss of more than 80 percent of the original diversity found within the hypothetical gene. A population of 500 people would not be sufficient either, Smith says. "Five hundred people picked at random today from the human population would not probably represent all of human genetic diversity . . . If you're going to seed a planet for its entire future, you want to have as much genetic diversity as possible, because that diversity is your insurance policy for adaptation to new conditions." A starting population of 40,000 people maintains 100 percent of its variation, while the 10,000-person scenario stays relatively stable too. So, Smith concludes that a number between 10,000 and 40,000 is a pretty safe bet when it comes to preserving genetic variation. Luckily, tens of thousands of pioneers wouldn't have to be housed all in one starship. Spreading people out among multiple ships also spreads out the risk. Modular ships could dock together for trade and social gatherings, but travel separately so that disaster for one wouldn't spell disaster for all. 'With 10,000,' Smith says, 'you can set off with good amount of human genetic diversity, survive even a bad disease sweep, and arrive in numbers, perhaps, and diversity sufficient to make a good go at Humanity 2.0.'"
A population of 150 people, proposed by John Moore in 2002, is not nearly high enough to maintain genetic variation. Over many generations, inbreeding leads to the loss of more than 80 percent of the original diversity found within the hypothetical gene. A population of 500 people would not be sufficient either, Smith says. "Five hundred people picked at random today from the human population would not probably represent all of human genetic diversity . . . If you're going to seed a planet for its entire future, you want to have as much genetic diversity as possible, because that diversity is your insurance policy for adaptation to new conditions." A starting population of 40,000 people maintains 100 percent of its variation, while the 10,000-person scenario stays relatively stable too. So, Smith concludes that a number between 10,000 and 40,000 is a pretty safe bet when it comes to preserving genetic variation. Luckily, tens of thousands of pioneers wouldn't have to be housed all in one starship. Spreading people out among multiple ships also spreads out the risk. Modular ships could dock together for trade and social gatherings, but travel separately so that disaster for one wouldn't spell disaster for all. 'With 10,000,' Smith says, 'you can set off with good amount of human genetic diversity, survive even a bad disease sweep, and arrive in numbers, perhaps, and diversity sufficient to make a good go at Humanity 2.0.'"
By the time we have the tech to build a starship we can just ship out as many embryos as we can fit in a freezer. Job done.
No sig today...
With technology, we can preserve a lot of genetic diversity in frozen embryos, eggs, sperm. So there are ways of mitigating the risk of genetic trait loss with a lower population.
How about a smaller sample of people and a large sperm and egg bank instead?
According to a book I've read: Two of opposite gender (along with some other people from somewhere).
We're not far from being able to check-box for all the SNPs and phenotypes we want in offspring. The idea that we need to ship around tens of thousands of mouth-breathers just to maintain "diversity" is about as ludicrous as saying we'll need stout men to construct shelters upon arrival at the far side.
If it's just genetic diversity you're worried about, why send the people themselves? It seems to me that sending that many people would be a massive over-expenditure of resources. Why not send much more manageable number of people to run the ship and build the initial settlement along with preserved genetic material for a massively larger population. Breed, predominantly, through artificial insemination for the initial generations until you are back to having the desired diversity in the actual living population.
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A lot of people (not us Slashdotters, of course) have the misconception that other solar systems are right next door to ours. So I always illustrate it like this: The fastest spacecrafts we've ever built take about 9 years or so to go from Earth to Pluto. At that rate, they would take about 120,000 years to reach the next closest solar system. I also saw a great illustration once using a quarter (coin), to represent our solar system, and the next solar system being something like two football fields away.
SJW's don't eliminate discrimination. They just expropriate it for themselves.
Just need 1. Clone said person over and over. Why assume that diversity is good? Do we really want to send reality TV loving cretins to colonize other planets?
01/01/01
Why not just allow for inbreeding and do continuous genetic testing on all embryos generated, terminating those that will turn into West Virginians?
Five hundred people picked at random today from the human population would not probably represent all of human genetic diversity . . . If you're going to seed a planet for its entire future, you want to have as much genetic diversity as possible, because that diversity is your insurance policy for adaptation to new conditions
when it comes to preserving genetic variation
Except that's not the goal.
If you're talking about colonizing another star system (presumably this is way the fuck after we colonize mars, the moon, IO, Titan, Venus, Murcury, and whatever else we feel like) then little things like genetic diversity upon reaching the target are of little concern.
No, you care about GETTING THERE with enough wits about you that you can continue to function, and set up something to expand your capabilities.
The fight is not to keep the diversity we see on earth circa 2000, but rather the fight is against inbreeding from making everyone retarded to the point where they can no longer function.
Once you get there, and establish colonies, food supply, and your ecosphere can expand past the mothership, you can breed like rabbits and let nature take it's course to overcome whatever detrimental effects that being cooped up in a closed space for 30 generations might have had.
Or every generation could be a fucking clone while on the way there. Seriously, this is colonizing ANOTHER SOLAR SYSTEM. This is WAY OUT THERE. It's science fiction. Just what the hell were you planning of propelling this ship with for 30 years?
Hell, taking the long view, just spreading ANY form of sustainable life is a viable goal for this sort of project. At this scale, "humans" are transient things.
I don't know, but bring woodchucks for giggles.
Table-ized A.I.
They're not calculating the needed number of colonists, just the preferable number to maintain genetic diversity. But there are other ways to maintain diversity. Many thousands of frozen sperm, eggs, or embryos could be taken along. Colonist embryos could be analyzed and selected for diversity en route. Or diversity could be ignored and things would very likely turn out just fine, especially considering embryos with genes for disease could be replaced.
Bitched about Hasselton on the other article and Pickens shows up with something even more asinine.
This is a very old anime on this topic, check it out! Available on youtube.
..... its the rest of the ecosystem that is the real challenge.
I wonder if they are taking into account whether the people involved will want to procreate with each other. Just because there are enough bodies to maintain adequate diversity, doesn't mean everyone will happily pair up to make that happen. That is a much more difficult calculation. That being said, if you have a short list of potential breeding partners, some people will become less picky.
Ninjas don't carry tic tacs
To me, the question is not really how many people, but how many earthworms, and in general plants, bugs, birds, animals, etc.? At present, we really have no idea what is needed, nor in how much variation within each species, but I suspect the real answer will always be "more that we think."
But horny ones.
Sig? Heil
the GMO mono-culture which wipes out all with roundup, and allows to live only sterile copyright gmo seeds at the expensive of the natural diversity of nature — in mexico, the many many varieties of corn are replaced in america with a mono-culture of sterile gmo seeds — it is insidious destruction of our own planet's natural and abundant diversity.
Why is a generation only 10 years?
Just take frozen sperm to diversify.
"If any question why we died, Tell them because our fathers lied."
We will be sure to follow. Tip 'o hat to Hitchhikers Guide
Who would agree to die in space and not see your home, friend ans family again?
I am a man. I am a volunteer to go on such a mission, as part of the first generation. I will necessarily have to breed, in order to do my part for overall mission success. Does this mean I may have to fuck a woman I find ugly, dumb, boring, vulgar or otherwise unattractive ?
On a vaguely related note: Assume you send N ships on this voyage. Do you send N copies of the same ship, and hope the design has no fatal flaw (while acknowledging the advantages of parts redundancy) . Or do you send N different designs in the hope that diversity of design is overall more reliable?
It's obviously 8 people, like Noah. Welp, that takes care of that!
While you would clearly be getting volunteers for the start of this task, there is an ethical dillema as far as future generations. Just because parents / grandparents / great-grandparents were totally OK living their entire lives in what would be a fairly finite space, it doesn't mean some members of a future generation wouldn't consider it torture. I guess it might be hard for me to see things from their eyes since they would be born into it, but I'm thinking that after I got to learn some history and see some videos / pictures of Earth, I'd be pretty unhappy stuck on a spaceship forever. I wonder how many would refuse to breed and do the same to their offspring (which would screw up the "diversity", or decide to turn back, or just go stark-raving-mad and murder someone or everyone (destroy the ship), and then your genetic diversity is REALLY screwed.
The Captain, his wife. Their sons, and their sons' wives. That makes eight for genetic diversity. Add some mutations afterward, and you're golden.
When you have radiation...
It only takes 2... duh, that's how we started on Earth!
This whole traveling to other planets is useless
You do know that Planet Earth has a finite future, right?
I want peace on earth and goodwill toward man.
We are the United States Government! We don't do that sort of thing.
I don't care if it's enough, just put me on the next spacecraft with Mila Kunis and Scarlett Johansson... Everything will be just awesome!
If you want to preserve genetic diversity in a small population, just learn to genetically modify the gametes at will to produce the desired variance. And that is well within the possibilities of the current genetic engineering technology, a few years to refine the technology and make it safe for humans and we are good to go. Now, if we could simply put all the anti-science crowd in a nice and comfy padded room...
If you send too few people out then production won't be high enough in the beginning. You need to send a fair few billion out to at least the first few star systems so that the population can grow, then once the colony is establish, you need to ship people back to maintain production levels on the home world. This is basic stuff people.
May the Maths Be with you!
What about intergenerational genetic transfers? No persons genetic info should ever be lost in such a scenario.
Even now we can freeze sperm and ovum.
Also we would not need to send 40,000 people. Just that many genetic samples.
Early human population dwindled to as few as 2000 individuals with most living in isolated pockets of a few hundred. Given enough time the population and genetic variability rebounded. Colonization of other worlds is most definitely a long-term project and while a bigger sample might give you better chances its probably possible with far fewer individuals.
Increase diversity artificially by having everyone exposed to hard radiation in interstellar space!
42
You only need eight people, and one ship that's only 300 by 50 by 30 cubits is enough to carry all the other animals and supplies required to completely start from scratch. Study it out.
But there is another problem which has not been addressed: Keeping or even raising the technological level of this population. Even a population of 10.000 will be very small in this respect. Evidence: The early inhabitants of Tasman Island arrived by boat and knew how to make arrows and such, but their descendants lost all that know-how. Sure, writing it down will help, but if you need to quickly expand your knowledge (for fighting new pathogens, for example), an isolated population of 10.000 humans will not be enough.
Looking things up in a book is not enough, practice is needed as well. There are plenty of skills which had been developed earlier in the last century which now have been lost for the most part (think of analogue control as an example), even in a population of 6 billion people.
You know it's time for the next revolution when your rulers' names end with roman numerals.
...had it right, enough people came to earth
How many people does it take to colonize this star system? Apparently more than the 6 Billion we have on Earth, since we haven't even bothered to get off this damn rock.
Send people to Mars first, then worry about Alpha Centauri (which is a terrible place to send people to anyway. The only thing there is a backwaters galactic planning council office)
--Joe
Assuming the closest is even viable, which it probably isn't, 4.2 Light Years = 39735067984839.36 Kilometers. The fastest thing (only thing) man has sent out of our solar system is Voyager 1, which at its current speed, if it was pointed in the right direction would take about 73,775 years to reach the target. Considering you probably don't want to run into it at that speed, you will have to accelerate and decelerate. Which it doesn't have the fuel for (never mind its RTG energy source is only good for 60-80 years), but even if it did would roughly double the time to reach the intended target to about 147,550 years. OK well that's not quite true, it would only add an insignificant amount of time because not a lot of time was actually spent to accelerate in the first place. However in the example below where you do not coast for tens of thousands of years, and accelerate til the midway point and then immediately start to decelerate it would double whatever you speed VS distance is anyway.
Sure you could accelerate and decelerate much harder than that to get there much faster, approaching whatever value of c is currently capable at launch. However by any measure, unless some magic energy source and method of propulsion is devised, the required energy at least at today's standards would require carting around the hydrogen energy mass of our sun for the trip. Some other methods of insitu material gathering such as ram scoops picking up interstellar dust are as likely as the fiction, as again unless some dark matter type thing which is everywhere (presumably) is harnessed, the amount of mass available is pretty low, space as it turns out is pretty damn empty.
Not to mention the weirdness of relative time as one approaches c on a ship compared to Earth, as while it may take less than the 75k years voyager would, here on Earth many more years will have elapsed. As to how many, I have no idea, that is beyond my math calculating ability (as is generally most of what I have currently written I am sure will be pointed out).
Never mind trying to maintain a ship, machinery, technology, or even a society that long!
More likely colonization will involve self replicating and regenerating robotic ship carrying a genetic payload and an informational database (likely with a terra forming mission proceeding it). Which would be more like favorable seeding for similar evolution and life to occur, than an actual "colony". Then again, that would also require pretty adaptive programming and AI, which would likely mean we would probably be fertilizer for our robotic overlords petunia plants.
So I guess I am saying as a thought experiment it is sort of interesting, but at this point (or any really foreseeable point in our future), it is all a bit far fetched by even the loosest standards.
We should combine this thought exercise with the recent article about the theoretical possibility that we will become physically immortal in the foreseeable future. No reason to half-ass nonsense thought exercises. High comedy... to have a few generations of people born and dying on a starship only to hail the call to dock with another ship one day delivering the GREAT news that someone discovered a faster way to travel.
Would more Females be beneficial?
If it would then as a Basement geek, who needs no sun light sign me up.
Sure, if you *cap* the population at 150 during transit, and don't allow multiple pairings within the same generation of course you're going to kill the genetic diversity.
However, if instead of a generational ship we were talking about hibernation until arrival, 150 is enough to begin a genetically viable colony. How do you avoid the risk of inbreeding? Simple: no cap on the number of children, but no full siblings allowed. Encourage as many different genetic pairings as possible.
---- El diablo esta en mis pantalones! Mire, mire!
If you don't mind some serious inbreeding. :)
They have bigger genetic diversity. According to Wikpiedia:
" The recent African origin theory for humans would predict that in Africa there exists a great deal more diversity than elsewhere, and that diversity should decrease the further from Africa a population is sampled. Long and Kittles show that indeed, African populations contain about 100% of human genetic diversity, whereas in populations outside of Africa diversity is much reduced"
Distribution of variation
All you must do to ensure this is guarantee that the generation before arrival is able to be impregnated with human children, and bear healthy young. Then you could have a repository of ... ahem ... genetic material from as many people as desired. In fact you could continue allowing insemination after planetfall - and effectively carry the genetic diversity of hundreds of thousands of unique donors, with a minimal crew.
Now about protecting the integrity of the .. genetic material. That might require sterner engineering.
This is a naive estimate—typical of wide-eyed wanderlust—looking at one tiny piece of the problem.
I'd say a population of about a million is necessary to maintain working contact with human technological culture, and pass this working contact on to the next generation. There's a bit of a gap between a Wikipedia article on metallurgy and a guy who has practised the profession for several decades.
In anthropology, often when a smaller population contracts major technologies are lost, not because they are forgotten, but because there isn't enough bread of expertise to sustain the technological cycle.
Actually, the history of remote island colonization on Earth showed that the minimum population that can "survive" genetically, socially, culturally, and economically in an isolated location is approximately 5000 people.
Instead of trying to move 40,000 people 5 light years away you move 100 along with 39,900 sperm and egg samples.
or even frozen spermatazoa would provide the entirety of human genetic variation save for the mTDNA components.
Take along a bare number of colonists, keep them all female by culling, add genetic information to the pool by randomized gamete selection.
Of course, the selected population would HAVE to be entirely gay or asexual.
2) It assumes that transportation will take 100's of years. Within 100 years, our space technology should be able to deliver 10 people 4 light years away (one way trip), in no more than 50 years travel time. That is two generations.
3) There is no reason to select people 'randomly', we can easily intentionally select people non-randomly, making sure that they have minimal DNA in common. Often 'random' ensures that weird coincidences happen.
4) The Toba theory claims that humans had a bottleneck of 3,000-10,000 individuals. 10,000 is a HIGH end, not a low end of what we need.
excitingthingstodo.blogspot.com
I think it's a little off base to assume that the population would be anything other that carefully chosen. This would easily be the most expensive endeavor in human history. Assuming that any *known* variable wouldn't be painstakingly planned for just doesn't take into account the following.
1) An engineer's love of problem solving and over thinking things
2) A bureaucrat's love of committees and covering their own asses
We would probably see planned "pairing" if the stake holders could get away with it.
P.S. After a little bit of further thought, we probably wouldn't have to have 100% genetic coverage. Some diseases would be relatively easy to keep out of the system.
Case in point: malaria
It would be fairly easy (relative to the scale of the overall project) to keep mosquitoes out of the ship. A clean room airlock transition for the people boarding the transport, and decontamination procedures (opening the transport to the hard vacuum of space would work) for the transport post disembarkation would probably suffice. Without malaria, we would have no need for the gene allele that adapted to combat malaria, i.e. the allele that causes cycle cell anemia.
that whoever plans such a mission does not base it off dreadful sci-fi like the new show, The 100. I was actually looking forward to this show, and now after three episodes, realize it's nothing but an intergalactic Lord of the Flies.
Funny, BSG ended up with, what, a bit less than 40,000 survivors by the time they landed on Earth?
Generation ships are impossible** for humans, which will likely cause our extinction.
Although technically and logically, it is not an insurmountable problem. You need a small crew, 6 or 7 women per generation. A high number of frozen male and double that many frozen female embryos (which we will assume are viable forever, though we don't know).
All crew members birth one daughter. If one is not successful, one crew member births 2 daufghters.
They are raised to be the next generation of crew.
Many generations later, strict population control (through gender homogeny) 6 or 7 women will land on target planet (or more likely orbit it)
Exploratory team of males/females are raised during the last "transport" generation, then they are sent on a lander as a pilot program, meanwhile another generation of female crew is needed.
If pilot program is successful and either farming is not needed (if gatherer lifestyle is possible on destination) either send more landers, or land the craft and begin large scale birth-rate increases, with every female birthing 6 or more embryos as health allows.
While using up the rest of the embryos (which will be an exponential thing) Ease humanity into a reproductive lifestyle, as it will be culturally foreign to them.
**This requires so much space culture cooperation and "unethical" planning that humans would never do it. We are more likely to spend all of our natural resources to make a GIANT space ship that crashes and kills thousands of people instead, because of the "religion/culture" problem, which is unsolvable.
... to the task of trying to rescue or repopulate species right here on planet Earth, and then use that as the most objective argument ever for why they should never become "endangered" in the first place.
Hrmm.
http://www.urbandictionary.com...
I don't think this will contribute to genetic diversity....
My opinions are my own, and do not necessarily represent those of my employer.
Sending meat bags into space is not very practical at all. It's more likely that we'll develop nano-factories and the capability of offloading intelligence into machines. Then we can just create intelligent space drones that replicate themselves as they go along and thus populate the galaxy.
This is actually one of the reasons why some think there is no extraterrestial life advanced enough to pull this off, as we would have noticed it by now. The reasoning behind this is that any society that has such capabilities more than likely destroyed itself before being able to reach this state. Of course, we might just be the first in our universe to pull this off, but don't count on it.
Acceptable as a thought experiment, but you didn't consider the hundreds of thousands of people who have to live through the time span.
They will probably evolve slightly to adjust to different gravity, sun color, atmosphere even if it is artificial, and food. Starting at a disadvantage due to lack of diversity is just cruel.
Genetic diversity is right after water, food, and air in terms of a population's survival. On earth it is not so obvious because we evolved here, and there's plenty of us. If it were another earth, diversity would not matter beyond preventing inbreeding. How likely is that scenario?
Don't send people; send bacteria.
Bacteria are nanobots. They will rapidly colonize the planet, terraform it, and evolve into ideally suited organisms that will result in a biodiverse ecosystem in just a few billion years.
Since total human population dropped to about 10,000 during the Toba super volcano 50 to 100 thousand years ago his estimates are obviously too high.
This estimate seems to based on natural reproduction and natural selection of sexual partners. The first interstellar colony would be anything but natural. Clones, genetically altered humans, controlled mutations...
We should give up trying to save pandas, kakapos, Javan and Sumatran rhinos, cross river gorillas and many more. The diversity is not there. Now lets talk about bringing mamoths back.
Ten women for every man and they woman ..."I hasten to add that since each man will be required to do prodigious... service along these lines, the women will have to be selected for their sexual characteristics which will have to be of a highly stimulating nature. "
30 generations in 300 years? They need to provide more entertainment on the ship...
Why do you need genetic diversity? By the time we're ready to send someone we'll have the ability to genetically engineer ideal traits in humans.
Over the course of 30 generations random DNA mutations will naturally propagate through the population, and these random mutations will be more prevalent in space because passengers would be subjected to high levels of radiation. For all intents and purposes you would only need to send enough individuals to perpetuate the population ad infinitum, and the minimum amount for this to happen is 32 people. Genetic evidence suggests that all humans alive today, despite apparent variety, are descended from a very small population, perhaps between 1,000 to 10,000 breeding pairs about 70,000 years ago.
The bottom line is natural selection will inherently diversify the population. Furthermore, you wouldn't randomly pick people to go on an expedition because you don't want that kind of genetic variability. There would be limited ability to manage individuals that are prone to diseases or stupidity, so this would be an exercise in eugenics.
So I ask again, why would you want to introduce random variability into a system that engineers have optimized?
the toba event states that as many as 7000 , and as little as 3000 humans survived
and look how we turned out..(oh ya nvm)
Oddly forward-looking number for colonization... from a decades-old science fiction novel.
Modular ships could dock together for trade and social gatherings, but travel separately so that disaster for one wouldn't spell disaster for all.
Did they take inspiration from the Migrant Fleet?
Actually, it would do fine -- for a specific population.
You would need multiple such populations, because multiple population types exist in humanity.
Mixing populations would destroy diversity faster than anything else by approximating a mean.
Futurist Traditionalism
The creators of Battlestar Galactica must have known this, with their 50,000ish population.
5 Million Years to Earth.
We are the Martians.
If telephones are outlawed, then only outlaws will have telephones.
Yeah, in fairness we should do it this way!
While we are at it lets select 50 random people to plan the journey. Then lets pick 5000 people at random to build the ships. All the software will be written by people selected randomly from the populace. We will pick the pilots at random from the populace!
This "pick people at random out of a sense of fairness" can't fail! This it like the world ending scenarios where people are picked at random to survive and not selected as those who give the species its best chance of survival. It works fine in TV and movies.. It fails in real life.
Just bring along some genetically diverse gametes and a IVF kit.
Something Something Chuck Norris.
What could go wrong?
Generation ships are pointlessly risky, heavy, expensive and tedious for the inhabitants. Accelerating a city of humans to acceptable speeds is just bad scifi. Rather than the colonists being born en route in some miserable spaceship full of stressed cooped-up people, I say it's better that they are born at their destination, in an orbiting nursery that could partially be constructed from local materials. The parenting would have to be done by AI and the gestating would happen in an artificial womb, but both of these technologies will be ready long before a suitable propulsion system is perfected. There are already independent reasons to pursue both parenting/tutoring AI and artificial wombs for terrestrial applications, and I expect that both systems will be usable in the lifetimes of some of today's slashdotters. Children being raised by AI is potentially controversial, but before long, AIs will be better at parenting than the many millions of bad human parents in the world today, who still get to keep their kids. And it will keep improving, even if human parents don't.
The worries about genetic diversity are just stupid. We could easily just bring along frozen fertilized eggs, which will remain viable with proper shielding for even a century-long trip. These could be gestated by the early generations of colonists, or by the artificial wombs that they brought along. But I would think they'd serve as a backup. Much less cumbersome would be to simply transmit some suitable DNA sequences from Earth once the colony ship arrives, and print it to DNA using Venter technology that we basically already have. The process is less likely than freezing to introduce errors. The privilege of instantiating your DNA in another solar system could be a reward for super-awesome human beings that do cool stuff in the decades that the ship is en route - a kind of Nobel Prize for being a worthwhile person.
The point of any stellar colony ship is to travel light - as light as possible. That means bringing 3D printers that could use materials at the destination to make the stuff that the colony will need: initially, a space station and its facilities. If this payload is light enough - just tools that are able to make the necessary tools on site - then conventional nuclear propulsion might be enough to accelerate the ship to an acceptable speed, and we'd be ready to launch in a mere 150 years. In comparison, a cumbersome ship that hosts a city of 40,000 people, plus all the farms they will need to stay alive for a century, plus all the facilities they will need to keep from going insane, will launch ... never. Because it's a stupid, stupid idea.
Rather than send actual live beings, wouldn't it be easier to set up a system that is constantly transmitting human genetic sequences into the cosmos, along with instructions for taking that data and turning it into live humans at the other end. This approach expends minimum energy and could result in the widest possible distribution of human descendants. Of course it relies on the existence of intelligent beings that would be willing to synthesize real humans from the data we provide them. But the odds of that happening are probably better than the survival of a generational starship to even the nearest habitable planet. Such a system could be built to transmit autonomously for thousands of years, and could even outlast our species.
We've shit all over this planet, we shouldn't be blasting off to other sections of the universe to shit all over them too.
You don't need people for genetic diversity...just the ammo to make more. What is the minimum number of people you need, plus what variety of stored eggs and sperm (stored safely for 1000 years), do you need...I would imagine way less than 100 people. And it would be best if they were all women.
Trying to colonise another star system by generational starship would result in all occupants being dead a long time before arrival: All the breathable gases would leak out through the hull of the ship by osmosis. Like faster than light travel millennium starships are just more fantasy.
Voyager and all the other space probes suffer from a massive problem: they have no (functioning) engine.
They got an initial boost from a chemical rocket to start out their journey. They used up what little fuel they had on orbital adjustments, not propulsion, and then got some velocity boost via gravity-well slingshots.
Any inter-stellar transport WILL have a engine, that continues to function for the vast majority of the trip. Current bets are on some sort of a ion engine, with solar sails being a nice runner-up. Both of them are low-thrust, long-duration engine types that don't require massive amounts of fuel to be stored on the vessel.
In either case, it's well within current engineering reason to presume that your inter-stellar engine can produce a thrust acceleration of 0.01g across several decades, at a minimum. After a year at a constant 0.01g, that means you're moving at about 3.1E6 m/s, or about 0.01 C. Even at that slow-poke speed, you'll cover a light year per 100 years. If you can accelerate for a decade (and decelerate at the end at the same rate), you get up to 0.1 C velocity, which means you cover a light year per 10 years.
You're only off by about 5 orders of magnitude that reasonable tech can provide now.
There are always four sides to every story: your side, their side, the truth, and what really happened.
This study relies ridiculously on traditionnal generations. By the time we have enough energy to get there, life will be way longer, there will be cloning, and women will not be needed for bearing children. One may even send just clone embryos of the selected astronauts, plus android robots to raise them upon arrival. Farther, imagine replicating the astronauts brain in an artificial simulation. And I'm jut thinking aloud a couple of minutes, no doubt the future will invent more surprising solutions. I just wish I were there.
Let's go ahead and send him off so we stop seeing these useless spammy articles that direct you to his spammy ring of websites.
Scientists have already sequenced mitochondrial DNA, and have show that the entire human race alive today descended from 2,400 mothers that emerged from the last ice age ~12,500 years ago.
Genetic diversity is not a concern for the voyage itself, just the colonization part and for that the answer is digital.
For the voyage, how many generations are we talking about until we reach the destination? Given a planned mating structure, and proper screening methods, we could send a few dozen and maintain a stable enough population to run the ship.
For the colonization, synthesize. We're doing it already. An entire functioning yeast chromosome was synthesized recently. Now I'll grant there's a difference between 270,000 base-pairs in a yeast chromosome and the 3 billion base-pairs that make up all 23 human chromosomes, but we're perhaps a decade from that point.
So we collect some genetic material from the population of Earth, screen out some not so friendly alleles, sequence and store the sequences in a computer on the ship. Upon arrival, the crew begins synthesizing DNA for millions of genetically distinct embryos. These can be grown in artificial wombs and/or the arriving women.
We may not be long away from some steps being entirely unnecessary. Future, then existing genomic databases may prove enough for a well written algorithm to create diversity on its own instead of using screened samples of naturally occurring DNA. I'm not sure I've made the distinction clear enough here as both situations rely on natural DNA at some point. What I mean is that under the first scheme, you collect samples, screen them and then digitally store, and later use, them unmodified. Under the second scheme, you use then existing databases built on past samples, screen them for undesired variants and have entirely new DNA generated by a computer.
Point is, you don't need to have all the genetic diversity walking around on a massive ship or fleet of ships. That's just silly.
Diversity is far more important, for many more reasons, than you believe. Some of the article covered why. But I don't have time to argue it, instead I'm just going to laugh at your forever marking yourself in support of incest.
...to do a geneticists job.
Inbreeding is a problem because it increases the probability of a person acquiring duplicates of defective genes, but if you are starting with people with genomes that are as perfect and diverse as possible you just need to send me and 50 Brazilian women. ;-)
I'm pretty sure the 13 colonies in Galactica had about 47,000 survivors at the beginning. +1 for a healthy gene pool apparently.
This guy is going places... I like it.
There have been many times in history when humans have established isolated colonies. How many can you think of that perished because of lack of genetic diversity? Even an ethnically homogeneous group like the passengers on the Mayflower did fine with a population of just over 100. 10000 or 40000 is unnecessary.
While the study is an interesting exercise in genetics it is probably of little use for interstellar colonisation.
When the ships arrive at it destination they will either find a planet with no biosphere (and an atmosphere of methane and ammonia) so the colonists will need to hang around for a few million years while one is established - or - the planet will already have its own biosphere and the inhabitants will consider the colonists to be a tasty new food source.
We need to remember what happened to the Martians in War of the Worlds - much the same would likely happen to us if we went to another planet that already had life.
The only way anything vaguely human is going to see other star systems is if we find a way of loading our minds into mechanical robots.
You send the information needed to make them and robots to teach them.
If you've read the James P. Hogan novel about this at +1 to your geek cred.
If you can name it without googling +2
I'd go on a Vegan diet but the delivery time from Vega is too long. --brownkitty
Genetic distance is an interesting concept, since there isn't a single axis of genetic diversity, but many. I would imagine that you could probably graph a genome as an N-dimesional hyper point, where N is the number of distinct genetic characteristics. The math of higher dimensional space isn't that complex, but it's interpretation can get weird, because what is 'genetically far enough' apart? Also, the space may not be smooth and continuous, so how do you know that you have an 'adequate' coverage? While it seems counter intuitive, it might be best to just pick N random people from the gene pool, where N is large enough to be mathematically representative of the larger population.
HA! I just wasted some of your bandwidth with a frivolous sig!
Yes, two copies of deleterious alleles is what you're trying to avoid with respect to inbreeding within families, but when you're talking about the species as a whole additional diversity is very much desired. Such variation allows some of us, and thus the species as a whole, to survive things others would not such as types of infection.
The colony won't be bacteria free. Forget that we haven't really managed to do a perfect job with clean rooms. Even if we did and the whole ship was bacteria free, the people wouldn't be and we need the microbiome inside. E.coli for example is much closer to you right now my friend than you would probably like to know.
Are we still talking about physically packing specimens of homo sapiens in some kind of gross physical vessel and somehow propelling it across interstellar space? Seriously?? This is the 21st Century, man! It's been obvious for a while now -- several decades at least -- that there are far, far more efficient ways to colonize the galaxy.
By the time interstellar travel becomes feasible, in terms of both technology and resources, surely our AI technology, our robotics technology, our molecular synthesis and manufacturing technology, and our understanding of biology and genetics should be easily advanced enough to ship a manufactory to the destination star system and then FAX across everything and everyone else that is needed there. The explorers and colonists are most likely to be AIs and robots -- although there's nothing to prevent transmitting and synthesizing human beings as well, if it makes any kind of sense to do so. (A human being off planet Earth is like a fish out of water, unless and until we win the cosmic lottery and stumble onto Earth 2.)
I just... I don't know what people are thinking when they trot out these star travel ideas that sound like something from the 1960s. Star travel is an idea about the future. Why do so many people look at this with their minds stuck in the past?
What could possibly go wrong? Hmm. Ask Cordwainer Bird about The Starlost.
PS. Worth googling if you don't understand the references to Mr. Bird and The Starlost
One to colonise. One to write the documentation.
Sorry, wrong joke.
Just send me with 10,000 women. Seriously, you never know: that guy might be wrong. C'mon... Just be open-minded! I'm perfectly okay with the risk!
Amazing System.
http://de.mon.st/RyEq2/
This is not axiomatic. Acceleration of 1G is well within our technical and biological means. From the spacecraft's POV, with turnover at the halfway point, 1G acceleration/deceleration to reach Proxima Centauri from here would have to be maintained for about 3 years, 8 months. That defines the energy requirements. They are significant, but not impossible.
Given a vehicle that can undertake such an acceleration for that amount of time -- this is the technical challenge -- and support its passengers safely as well, the trip is entirely feasible without a "generational starship."
Interested in how this all works? Here: Well worth your time.
And of course, if something along the lines of the Alcubierre drive can be brought to fruition, we'll go down another road entirely.
I've fallen off your lawn, and I can't get up.
Send a sperm bank and a handful of (very dedicated) women, deter first cousins or closer from breeding, population remains low it doesn't expand until the ship nears it's destination, it then expands at a predetermined rate to provide the workforce needed to construct the colony upon arrival.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
we should have the technology for practical immortality (a life span > 1000y). Combined with suspended animation, and AI to keep an eye on things, then colonizing the galaxy is obtainable.
Energy issues are the current road blocks to portable laser weapons and on a different scale, interstellar flight. It's not going to be trivial to find a way to constantly accelerate for months even at 0.1g, let alone 1.0 g. The mass required to do this, even of energetic substances, is rather incredible.
plug them into facebook with oculus rift units and they probably won't even notice they're not on earth. bam.
The initial crop of people are volunteers.
Any subsequent generations are effectively prisoners in an ark. They may not LIKE the fact they are on an ark. They may not want to go ahead with a eugenics program or even participate in this whole mission. They may even want to turn the ship around or just tune out and do SFA while the 'volunteers' do the work.
It's going to be messy. The series 'The 100' on Netflix appears to be exploring a similar sort of situation. The initial show premise involves a pre-series nuke war, space stations of Earth survive and conglomerate to produce the Ark, plan to wait a few hundred years to return to earth, 100 years short they discover a critical problem with carbon scrubbers that will take 6 months to fix but life support will break down in 100.... and they've already had to start putting lots of people in detention because they a) have too many people by reproduction and b) they have people who don't feel like they owe the system anything. It's an interesting study in exactly how draconian people on these sorts of space missions may have to become to maintain order and deal with crises like overpopulation.
-- Mal: "Well they tell you: never hit a man with a closed fist. But it is, on occasion, hilarious."
You do realize menstrual cycles all align with women on warships?
Can you just imagine what the colony would be like for several days out of every month?
And no men and you expect the them, over 300 years, to maintain a reasonable society that new folks would want to be born into? Not slagging women, just saying you are creating a gender imbalance in live population that cannot fail to have profound psychological and then cultural consequences.
This plan is a bad one.
-- Mal: "Well they tell you: never hit a man with a closed fist. But it is, on occasion, hilarious."
You send 3N of each type. (Of course, I am cherry picking - this assumes high (95-98%+ reliability) vessels and then 3 is the magic number for maximum redundancy I believe)
I'd send more than one type and more than one of each type. In fact, I'd figure out what my mission needs and dispatch 3 concurrently to the same place with minor separation (enough for something to happen to the first and another may avoid their fate or come in to save them).
Colonization is such a ludicrously big venture, it should be done on a big scale. By that point, Earth may well have a population of 9-13 Bn, so we can certainly spare about 120,000.
Whether we can beat the energy or resource limits is another issue entirely.
-- Mal: "Well they tell you: never hit a man with a closed fist. But it is, on occasion, hilarious."
In effect, for a few generations, you could introduce intentional mutations that are known to be somewhere between "marginally harmful" and "beneficial", until the gene pool is large enough that things can be left to random chance again, if the colonists desire.
Don't believe me? There is abook about it. And it will take 6.000 year. Tops.
Don't fight for your country, if your country does not fight for you.
If spaceships could dock together for trade and social gatherings, perhaps spaceships could also have war with each other even though they began as friends from the same nation, and maybe they would continue their wars once they start colonizing the other starsystem, as described in a science fiction story written by Sofia Koutsouveli. To put it simply, trade always creates war.
"30 generations in 300 years" means we expect each new generation of kids to have their own children when they reach 10 years old?
Critical Population for mammals is 3000.
150 would end in disaster.
Humans are a virus. I cannot condone spreading it other solar systems.
Depending on the game plan -- bootstrap from 18th century technology, or plant a clone of Earth society hauled out of storage lockers, or something else -- there's also the question of what to pack. And what the ancestors of the eventual colonists are to do while traveling.
Maybe they farm, if they're going to travel awake. And practice identifying and smelting ores, and turning trees into houses and waterwheels. Stuff like that. They'll need a lot of room. (And a way to turn metals into imitation ores.) All the while reminding the next generation that they'll need the knowledge in those books to make telegraphs and dynamos, and to refine silicon spice genes. Stuff like that. (See Heinlein's "Orphans in the Sky"/"Universe", and the New Beginnings chapters of "Time Enough for Love")
Or maybe they do something else while traveling awake.
If they travel asleep or frozen, they just need to know how to operate whatever supplies they bring along, when they come to and unpack: Conestoga wagons full of seeds and surrounded by livestock, city-in-a-box robo-kits, whatever.
There's no time like the present. Well, the past used to be.
You can have diverse children without different people. Just take sperm and eggs from other females. Then every child could be completely diverse.
I also don't think that genetic diversity will be as much of a problem as assumed. The chance of birth doubles, which sounds a lot worse than it really is. It goes from 2% to 4%. So 96 of 100 kids instead of 98 of 100 kids will likely be fine.
Also, since there is a great genetic shuffling in each generation (and that means a lot of shuffling in multiple generations), everything will be fine and by the fourth generation, everyone will wonder what the concern of genetic diversity ever was.
If we assume that humans evolve, then any small genetic base will expand its genetic diversity through the generations. Right?
Search The Sky, by Pohl and Kornbluth
Before we can even seriously think about sending people to other solar systems, we should colonize ours. We have not only seven other planets, over 150 known moons but also hundreds of thousands of small worlds -- the asteroids, the Kuiper Belts and beyond. With all these worlds the human population could reach into the trillions. Colonizing the solar system would allow us to build the infrastructure necessary to give us access to a lot more energy than fossil fuels could ever provide. With this energy and infrastructure it will then be a serious possibility to start sending out interstellar spaceship with the intent to colonize other solar systems.
Before we can even colonize the solar system, we must prepare for the end of our fossil fuel subsidy and stabilize our civilization and the environment. Then we can bank our collected energy savings from renewable energy generators like solar panels etc to start our colonization of the solar system.
...why would one assume the travellers would WANT to settle down at the bottom of a gravity well on a planet's surface. They've had 30 generations to evolve as a space faring civilization, and I suspect they would much prefer to continue to do so. After all, the whole of the universe may now be within their travel capability.
Why not just burn the cash instead? At least the fire would be pretty. A starship would be a waste.
According to Neil DeGrasse Tyson, there are three reasons why major projects are undertaken by people.
Defense
Aggrandizement
Economic return
No aliens, so no defense. Nobody has the power of a Pharaoh these days, so large egos go unserved. Nobody alive would get anything economically from a starship mission. So, no mission. These constraints may even keep us from sending people to the planets. After all, space has been waiting for us to go since the 60s. We've been unable to go. After 40 years of space travel, we now have 6 people living in low earth orbit, and depend on the Russians to ferry them back and forth.
Go to Heaven for the climate, Hell for the company -- Mark Twain
Waste of time calculating that. Every computer gamer knows you only need one person to colonise space. Sid Meyers! :-)
Sure enough, the cow costume was hanging up next to the superhero outfit and sailors uniform. (S,Spud)
The article highlights that 150 people is too low a number to preserve all the genetic diversity over multiple generations. This is in line with other estimates, that say that below 250 and 500 individuals, genetic diversity collapses rapidly.
But I always wondered: All these statements assume normal sexual selection, where some gene lines die out in the long run.
But what if one would remove the element of chance? What if you know the genetic pool of your colonists and could ensure over dozens of generations, that no genetic diversity is lost. Additionally, what if you could preserve the original genetic pool via cloning or DNA storage & synthesis?
Since the initial stock of colonists are presumably genetically healthy, it follows that their offspring should be healthy, too, if you eliminate loss of gene lines. And even if some issues appear, you still have the originals "on backup".
Of course, like others pointed out, such a strict procreation scheme might lead to adverse psychological effects in the population. :)
There is far more extractable energy in the uranium on this planet than in the oil.
someone that knows you?
ad hominem ftw!
Seriously, why not just let the people who aren't melding with society in that situation be early explorers of post-nuke Earth?
Such a situation would require something like religion to drum into children from a young age to be sheep and always obey their elders, to be a cog in a machine, to be honest. Just what religions did on this planet up until recently (oooh, downmods coming).
So you think they'll evolve a little and then their evolution will just stop?
Yes and no. There is "reasonable tech" and "current tech". My example was using current tech. Voyager is the only man made thing other than various emissions to leave our solar system. So I was using its speed as a base. Has ANY solar sail EVER been deployed successfully? I think the Japanese has a plan to use one, but that might be a far off pipe dream if I remember correctly. Ion Drives have been tested, on earth, and not for the duration you mention.
Anyway don't get me wrong, I think they should be experimenting with these technologies, particularly the ion drive. However what you call "reasonable" I think could better be described as "untested".
That said I would be much more excited about trying to launch something using an ion drive at a neighboring star, than a man on mars. One of the other obstacles is that of power source. Not sure what the energy requirements for a mission like that might be, or what an ion drive sucks down, but the only thing we have used so far are 40-80 year RTG producing somewhere around 500W of power. Long distance communication takes a lot, just keeping electronics uniformly warm takes a lot (tho by using a RTG you get some thermals anyway)...
Again my example about energy was using traditional propellant (saw it in a fact sheet someplace), as again that is all we have actually used so far.
Hell much of the older technology from back in the day has since been lost, like heavy lift etc... (though some effort is now being made to invent the wheel again).
Though heck if your calculations are correct, if they launched today, it would arrive in 42 years, and if sending transmission at the speed of light another 4.2 years to get any transmission, so 46.2 years, I *might* still be alive then to witness it! Then again, if it has to transmit by radio, I imagine it would take much longer indeed to receive any signal.