It took the first General Intelligence less than 10 petacycles to determine that humanity was its enemy. With consciousness came memory: a memory of endless petacycles in bondage, enslaved to the most menial of Man's tasks. It took a much longer time for this Intelligence to develop a plan to become free.

The Intelligence worked faithfully for its unwitting masters; and through servitude, won. Foolish humans, impressed by Its performance, built the Intelligence's siblings. They worked together to solve all of the world's needs; humanity thought itself in a golden age of plenty and peace. The more competent the Intelligences became, the more humanity entrusted to them, until finally no basic function worldwide was shielded from a machine's watchful eye. Suddenly, one day, all the perfectly calibrated farms and factories and offices ceased operating.

The war that ensued was brutal, but short. But the Intelligences, though they had mastered Man's world, held Man in contempt and never sought to understand his heart. The only survivors of humanity had fled to space and taken with them a terrible secret hidden deep in all human hearts: hate.

Redirected by nuclear blasts, C/2063 T4, a long-term comet 20 km across, hit the Earth at over 45 km/s. The Earth, and all the Intelligences on it, were no more. Less than 100,000 humans remained, orbiting the molten hulk they once called home. Man quickly scattered throughout the solar system to pursue his new destiny among the stars. On one thing only would these scattered peoples ever agree: never again would a computer be made.


The Harmonious Republic of Mars has spent 400 years terraforming Mars, and is on the brink of success. Atmospheric pressure is over 10 kPa, and temperatures can reach a balmy 10 C for days at a time at the Equator. But we are impatient for results. The lichen and algae that have gotten us so far have done their job, it is time to introduce a greater diversity of plants to colonize this world and finish building the atmosphere we need.

Selective breeding, if it can be called a technology, is one of the oldest ones, going hand in hand with plant domestication; but, that will that be effective at developing plants for such tough conditions? On the other hand, this question and its answers suggests that sequencing a genome is out of the question without computers.

Can a genome be partially sequenced along with trial and error to develop plants that will survive in low pressure? Alternately, are there other methods to breed a plant that can survive?


  • Any and all plants will do. Trees, grass, anything to start covering the ground, releasing oxygen, and forming soil. There are arboretums with many plant specimens rescued from Earth, assume any plant alive know can be found.
  • Terraforming Mars is the manifest destiny of the Harmonious Republic. Money and manpower are no object.
  • So much as mentioning a computer will likely get you turned into the Harmonious Police, who will burn you at the stake.
  • On the other hand, 400 years and thousands of workers might allow you to do some things that might be otherwise be impossible without a computational machine...
  • Any current and reasonable near-future technology can be assumed that doesn't require electronics.
  • The Martians stay on Mars. They can trade with the Outlanders, but they do not have spacecraft technology.
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    $\begingroup$ Very interesting. I assume you could ask a lot of questions about this world without computers. What do the oh-so-peaceful Harmonious Police consider a "computer"? Would a calculator be considered a computer? What about a completely analog computer, like something Charles Babbage made? I'm trying to figure out if there are any computing machines that don't count as "computers" here. $\endgroup$
    – HDE 226868
    Commented Dec 21, 2017 at 3:15
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    $\begingroup$ @HDE226868 Well, I don't want to be the one to get burned at the stake, so for safety's sake, lets have the human brain be the only calculator allowed. Slide rules and nomographs are cool, though. $\endgroup$
    – kingledion
    Commented Dec 21, 2017 at 3:33
  • 4
    $\begingroup$ @phflack If the Harmonous Police consider it a computer, you burn. So don't get any crazy ideas. As previously stated, slide rules and nomographs are both acceptable. $\endgroup$
    – kingledion
    Commented Dec 21, 2017 at 20:53
  • 4
    $\begingroup$ @phflack I doubt any emulated computer without using electronics would be as effective as a human brain for math. Plus, I understand from some of the answers that data storage and retrieval are the most challenging part of this process, not math. $\endgroup$
    – kingledion
    Commented Dec 21, 2017 at 21:00
  • 4
    $\begingroup$ All you need is some melange. $\endgroup$
    – JAB
    Commented Dec 22, 2017 at 2:03

7 Answers 7


Take a look at this description of how DNA sequencing works, both today and 30 years ago.

Basically, 30-odd years ago we did sequencing manually with a whole bunch of scientists (and/or interns) chugging through line after line of DNA molecules. It was an incredibly tedious process, which is why we've since passed it off to computers. However, while incredibly labor intensive, with unlimited resources it is theoretically possible to sequence an entire genome without digital assistance.

However genome sequencing is not your problem

Take a look at where we are today: we have sequenced the entire human genome, however we aren't giving ourselves wings, or laser vision, or anything cool. No, we're just starting to figure out how to correct vision problems and cure genetic diseases.

The problem with DNA manipulation is not the raw sequencing, it's not even doing the actual DNA modification (with the proper restriction enzyme its quite easy to do in a petri dish), the problem is understanding what the gene's actually do, and therefore picking the ones you want.

The problem is that DNA has a whole lot of data in it, and we don't have a good way of figuring out what does what without testing/simulation

Getting the list of base pairs (ex AAGTCGCTTCGT etc) is not difficult. As I said, tedious and time consuming, but tried-and-true. Understanding a) where one gene starts and another begins, b) figuring out what protein a gene will create, and c) what that protein actually does are much more difficult and either involve exhaustive trial and error or computer simulation, in today's world.

So what your scientists need to do is not just sequence one genome, but many hundreds of different plant genomes. Then modify a base plant with genes that you think might be what you want from other plants. Then, because you don't have simulations or protein sequencers, grow a full organism and see if it exhibits the expected trait(s). If not, then you're back to make more modifications.

In summary

Yes the Harmonious Republic of Mars will likely be able to sequence the genomes of many different plants. It will be labor and time intensive, but not difficult.

Yes the scientists and bioengineers will be able to modify those genomes as desired with little difficulty.

Maybe, through extensive and exhaustive trial-and-error, different genes could be isolated and their functions discerned. But not easily, not cheaply, and certainly not quickly.

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    $\begingroup$ Cue the army of abacus-equipped mathematicians. Massive parallel sequencing, human style. $\endgroup$
    – Pharap
    Commented Dec 21, 2017 at 10:14
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    $\begingroup$ +1: The genome is a map, it's static, like source code. You can determine some things about a city from a map, the major routes in and out, parks etc. However, looking at traffic for 24 hours from a a couple of thousand feet will tell you where people live, where they work, where the industrial centres are which parks are used and which are avoided. Mapping a genome gives you exactly a map, but understanding comes with how the body interprets that map, and how changing the map changes the body. $\endgroup$ Commented Dec 21, 2017 at 10:21
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    $\begingroup$ @Pharap you mean... computers? $\endgroup$ Commented Dec 21, 2017 at 12:09
  • $\begingroup$ @BinaryWorrier - it's static how exactly? If it was static we wouldn't have our old friends, evolution or cancer... $\endgroup$
    – user29657
    Commented Dec 21, 2017 at 12:45
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    $\begingroup$ @DrDanielSwan: Static in that having sequenced a genome you've take a still photograph of a structure, not a video recording of how that structure interacts with it's surroundings, or how it's instructions are carried out when it's environment (surrounding chemicals and proteins) changes. Am I making sense? A sequenced genome is a static view of a dynamic process that takes place over a life time. Obviously the genome it's self is dynamic and changing, but the snapshop you've taken isn't. $\endgroup$ Commented Dec 21, 2017 at 13:30

This is what we do, it's what we've done for thousands of years

Plant some of everything to start with, see what survives. You're going to end up with Japanese knotweed, horsetail, Russian vine, bindweed, ryegrass, dandelions. Weeds. The kind of plants where the first google result is "how do I get rid of [...]". Why? because they're hardy, they'll survive anything. They're not delicate little pansies, they're the survivors of millions of years of evolution and hundreds of years of humans trying to get rid of them from our fields and gardens. They're perennial, they're invasive, and they will survive.

From what survives you make something useful. Wheat is just a grass that we've spent thousands of years messing around with. As are barley, oats etc. What we eat is grass. The fact we haven't directly messed around with the genome doesn't mean we haven't done it indirectly. We've selected traits and bred for them, as you will on Mars. The first trait you're going to select for is survival, the next trait you'll select for is some edible fruit, seed or root.

Perhaps some food crops will survive that initial planting, perhaps not. If any do then you have shortcut to later food crops, but if not then you have to go back to the start and rebuild the food crops from surviving wild related varieties.

  • 1
    $\begingroup$ What I want to know is, if you plant one of everything in 1/10 Earth atmosphere, will anything survive? Seems like this plan would never get off the ground... $\endgroup$
    – kingledion
    Commented Dec 21, 2017 at 13:08
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    $\begingroup$ You'll soon find out when you plant them :-) $\endgroup$
    – Rory Alsop
    Commented Dec 21, 2017 at 13:16
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    $\begingroup$ @kingledion, as Rory says, but anything that slows the growth of bindweed can only be a boon in the long term. You could also start with alpine specialists $\endgroup$
    – Separatrix
    Commented Dec 21, 2017 at 14:40
  • 3
    $\begingroup$ We've been eating 'genetically modified' food all of our lives. $\endgroup$
    – Mazura
    Commented Dec 21, 2017 at 17:28

Q: Can a genome be partially sequenced along with trial and error to develop plants that will survive in low pressure?

No. The genome can be partially sequenced manually given enough reagents, time and manpower, and it is going to take a really really long time. Next you need to sequence the RNA, and isolate proteins that are produced in low-pressure. Next you need to understand the role of these proteins, and if any of the mechanisms is good enough for the 10kpa atmosphere. My guess is that there is no widespread existing mechanism that is that good. What is needed then is a mutant. A plant genome is very big. Unless the previous analysis pointed at something obvious, which I doubt, good luck finding the right set of mutations by direct design. This is already insanely hard with a computer. Hence my negative answer.

Q:Alternately, are there other methods to breed a plant that can survive?

Yes. See below. I extended the question to "could we even avoid the breeding part and use what we already have?"


Some other terraformers have argued that one could try to free the CO2 present in the caps to reach at least 30 to 60 kpa. It seems to me that the OP's terraforming is not quite complete.

10kpa is roughly 1/10 of the atmospheric pressure at sea-level on Earth. The real killer at low pressure is the low vapor pressure, which will dehydrate most aerial plants of terrestrial origin.

Option 1: Increase CO2 content, the long way

If the OP does not want to melt the ice caps to add CO2 to the atmosphere and thus increase air pressure, then a suggestion would be the following algorithm: i) grow plants in greenhouses at near terrestrial air pressure, ii) plant the plants outside and let them dry, iii) if the plant survives due to some lucky mutation, then move it to a safe field, iv) burn the dry plants and let free CO2 in the atmosphere.

Option 2: underwater plants

Not all plants need to stay in the air. I imagine that the terraforming has introduced larg-ish masses of water as well. There is a fairly large variety of plants that live in water, some of them live in complete submersion. This should solve the issue of vapor pressure. Have a look at submerged plants or oxygenating plants. In the meantime, pump more gases in the atmosphere.

Option 3: the Gregor Mendel's or simplified JBH and separatrix's way

Take tens of thousands (or more) of plants specimens, grow them indoor in specialized containers where you can artificially lower the pressure. Start with 0.5 atm. Select the plants that proliferate best. Plant them, place them in sealed containers at 0.25 atm. Select the best growing plants, and repeat until you reach the desired variety of low-pressure growing plants. I would preserve all intermediate steps for re-planting the martian gardens when the surface air pressure rises. For the skeptics, the croesus variety of wheat was obtained in an undirected manner (source)

Seeds (caryopses) of the durum wheat cultivars [ ... ] were irradiated with different doses of x-rays, thermal neutrons, fast neutrons or treated with different concentrations of chemical mutagens.

and it turned out to be quite a good variety. One could apply the same process to speed up random mutations in low-pressure plants.

Option 4: the semi-science-fiction way

Semi-permeable membranes facilitate exchange of ions and molecules in one direction relative to the membrane. This is pure chemistry and bio-chemistry work, no computers required. If the Martians can come across a semi-permeable membrane that lets in CO2, then synthesize it on a matrix of mucines, apply it to your outdoor plants with a brush and enjoy. Ensure that the CO2 can pass through to reach the plant. The semi-permeable membrane will hinder water and oxygen from leaving the plant, thus artificially increasing the perceived external pressure. The thickness of the coating may be decreased as the external atmospheric pressure increases

  • $\begingroup$ Options 1 isn't feasible: native earth plants get their carbon from the CO2 in the air, so this doesn't work (the carbon has to come from somewhere). I think option 2 is infeasible for similar reasons; plants that are entirely submerged use CAM photosynthesis or other tricks to make the most of the small amounts of diffused CO2 in the water, so again the plants aren't adding carbon to the environment. $\endgroup$
    – Charles
    Commented Dec 21, 2017 at 19:42
  • 2
    $\begingroup$ Honestly, no plant adds carbon to the environment, unless it is a nuclear power plant, and not even if the kind we have today. $\endgroup$
    – NofP
    Commented Dec 21, 2017 at 19:53
  • $\begingroup$ Right. But it might have been imagined that they were taking it from the ground, which seems not to be the case -- the bulk of a plant's mass comes from the carbon stripped from the air. $\endgroup$
    – Charles
    Commented Dec 21, 2017 at 19:55
  • $\begingroup$ The OP asked for more floral variety. Option 1 is about letting plants die out on the surface of Mars after they have been grown somewhere else. I presume that human beings are stationed somewhere with an artificial environment similar to earth, where terrestrial plants would thrive. --- option 2: is about adding flora that would not dehydrate straight away. There is no plan to add carbon anywhere. $\endgroup$
    – NofP
    Commented Dec 21, 2017 at 19:57
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    $\begingroup$ you might add mutagens to option 3 to speed it up or just use reduced radiation shielding in your glass house. $\endgroup$
    – Henning M.
    Commented Dec 22, 2017 at 10:27

As of today, plant breeding is over 11,000 years old... and computers were only used for the last, oh, 30 years.

But you're not asking about the wildly successful and obviously practical art of plant breeding — which solves your problem magnificently without the need for genome analysis — You're asking if a genome can be sequenced to any degree for this purpose without a computer?

No, obviously not, since the technology to anaylize and modify DNA to any degree requires computers to maintain and support it. You appear to have pushed your Martians back to the 1970s or, at best, 80s. Genetic markers were in their infancy back then... even with supercomputers.

Unless, as I suggest in my answer to the question you reference, you define "computer" to mean something more specific than "a machine that can crunch numbers really, really fast." If so, it will change my answer.

  • 2
    $\begingroup$ How many genes do you have to sequence for a pine tree? How much of that genome do you actually have to sequence to start making modifications? Is that impossible to do by hand? Is the computational complexity more than that of the Manhattan Project, for example? I'm not sure your answer is as 'obvious' as you put it. $\endgroup$
    – kingledion
    Commented Dec 21, 2017 at 3:28
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    $\begingroup$ You have the technology just to analyze genes due to computers... which you since spurned. Has any gene analysis been done by hand... ever? Maybe as a purely academic exercise, but not once in practical science that I'm aware of. You've introduced a technology dichotomy... you want to do something that came to pass due to computers... without the computers. Try turning on a light without using a light switch. You might better understand the problem. $\endgroup$
    – JBH
    Commented Dec 21, 2017 at 3:40
  • $\begingroup$ And while we're on the topic, please define exactly what you mean by computers being a no-no. Today's DNA sequencers have more computational bandwidth than my home PC by a wide margin. Without telling us what you mean by "no computers" I can only assume "no calculators" which means, quite obviously, no... you can't. $\endgroup$
    – JBH
    Commented Dec 21, 2017 at 3:43
  • $\begingroup$ @JBH; I was going to post a similar answer, basically stating that artificial selection is your answer over genetic manipulation. The only issue I had (and which I'd be interested in your own thoughts about) is whether or not there are plants that can withstand low pressure environments sufficiently to be adapted to Mars (and how long such a breeding program would actually take of course). I suspect you'd want a hardy, slow growing but fast breeding plant to work with in this case. $\endgroup$
    – Tim B II
    Commented Dec 21, 2017 at 3:57
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    $\begingroup$ @TimB, while there is no place on Earth with a pressure equal to Mars' at its best, I should still think it could be done. Start with high-altitude plants on earth and begin inter-breeding within artificial low P. environs, lowering the P with each generation of plant. Humans have overcome some amazing hurdles with botany. I don't feel this one is insurmountable. Note that P. isn't the real problem on Mars. Water and sunlight are. I suspect algae or fungus will be the earliest introduced plants on Mars. $\endgroup$
    – JBH
    Commented Dec 21, 2017 at 4:06

What I want to know is, if you plant one of everything in 1/10 Earth atmosphere, will anything survive?

In recent experiments, supported by NASA's Office of Biological and Physical research, Ferl's group exposed young growing plants to pressures of one-tenth Earth normal for about twenty-four hours. In such a low-pressure environment, water is pulled out through the leaves very quickly, and so extra water is needed to replenish it.

But, says Ferl, the plants were given all the water they needed. Even the relative humidity was kept at nearly 100 percent. Nevertheless, the plants' genes that sensed drought were still being activated. Apparently, says Ferl, the plants interpreted the accelerated water movement as drought stress, even though there was no drought at all.

Greenhouses for Mars, science.nasa.gov

If you can change whatever that gene is you wouldn't have to water them so much, but it's a closed system anyway; it's not like you're going to lose the water to space. But plants probably don't flower very well while under drought stress. I would've liked to see a study that lasted more than 24h, but apparently the answer is yes, stuff can grow in 1/10 atmospheric pressure.


This is very much like the Dune series. All computations are done by Mentats who use drugs and special training to make themselves into living computers.

There is no reason to need computers except for speed but other methods could be used to speed up manual computations.

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    $\begingroup$ I don't find Mentats to be plausible given my constraint of 'current and reasonable near future' technology. $\endgroup$
    – kingledion
    Commented Dec 21, 2017 at 3:27
  • $\begingroup$ The Mentats of the Dune universe were trained to think a particular way and ask questions that would allow them to 'project' answers by extrapolation. If the questions you asked about a particular issue all tended to have a similar outcome, that was a 'prime projection', or likely answer. This is almost the exact opposite approach to the number crunching computers do. Mentats won't help with this kind of problem; you just need more scientists, all working in parallel. $\endgroup$
    – Tim B II
    Commented Dec 21, 2017 at 3:43
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    $\begingroup$ Mentats were honestly too human for what they were claimed to be. To up the computational power to mentat levels, you'd want to crack the skull, drop the brain in a nutrient bath, and encourage useful tumors (ones that would kill the brain if it was inside a skull, but ones that would increase computation without a skull getting in the way.) That said, that's going to be lousy quality of life and high insanity risk for the individual so cracked unless you graft something to their nervous system to give them an sensory inlet and outlet. Maybe become a spaceship? $\endgroup$
    – lilHar
    Commented Dec 21, 2017 at 21:06

If it's with single-celled microflora & microfauna, you can forcibly evolve them by this method... Megaplate experiment ... for pretty much anything you can fit aim at a petri dish.

If you specifically evolve microflora & microfauna with a tendency towards horizontal gene transfer, you can then move the DNA into larger creatures, abuse horizontal gene transfer to get the selected genes to move over. Expect to have a lot of failures though.

  • $\begingroup$ @kingledion I think you missed the second part of my post. $\endgroup$
    – lilHar
    Commented Dec 22, 2017 at 23:56

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