# How could humans re-populate a new planet without conventional procreation

This question is a spin-off of this question

In my world humanity is faced with extinction and must devise a way to escape their barren planet. So say they take a space ship to the new planet and unfortunately everyone dies in a crash landing. Fortunately, the "INSERT BIOLOGICAL MARVEL HERE" that was loaded on the ship breaks/escapes/activates and human dna/rna/bacteria/etc is released into the atmosphere. A few hundred million years later, cave men rule the planet.

I don't know enough about science to come up with something plausible that would allow some kind of DNA-like (preferably biological, not robotic or "artificial" like bishop in aliens) stuff to ensure the continuation of the human race.

In my mind, the ship crashes, and two vials of liquid break and their contents are leaked onto the new world. Basically, what is in those vials?

EDIT 1

Although not complete, I had some ideas that may be fodder for your minds.

Idea #1:

If human DNA were to be altered so that not only the liver can regenerate, but the whole body? Is there some way of turning this into an exceedingly long process to give the planet some time to catch up?

Idea #2:

Could there be a way to re-wind human evolution to the early ocean dwelling stages? Say like a tiny organism or something else very easily transportable? Assuming that conditions are similar, I don't think it's too crazy to propose that an almost human species could evolve from that.

• "I don't know enough about science to come up with something plausible" - too bad. I'm afraid the more science someone knows, the harder it will be to come up with something plausible.... – Mołot Sep 12 '16 at 17:28
• But... is there any DNA-based life there? – Mołot Sep 12 '16 at 17:29
• Keep in mind it's for a book, so if I can fool 99% of the readers into not calling me on my shenanigans, I'm happy. – Matthew Goulart Sep 12 '16 at 17:29
• @Mołot if there needs to be, there can be. The planet is only devoid of any sentient life. So no humanoids, no quadrupeds, fish, etc... Just bacteria and microscopic organisms. Of course, if any of that makes it impossible, then I can bend the rules a little. The state of the planet is less important than making this question work. – Matthew Goulart Sep 12 '16 at 17:31

This is inspired by my imagined explanation of the weird opening scene in Prometheus.

Imagine you are a god of evolutionary biology: you're immortal (or near enough), you have experienced billions of years of biological evolution and many times have witnessed the emergence of complex organisms. You create a massively complicated system (lets call it the Codex) which encodes a secret nudge factor in junk DNA. The nudge factor is massive, elegant and flexible, but it's not small. Encoding it takes almost as much DNA as is used to encode the organism itself.

Every evolutionary step across billions of years is subject to nudges from the Codex. You're not controlling it, you're not monitoring it. You just it set up as a guide, a blind watchmaker, a steward of evolution. You encoded it into the first organism so every organism inherits it. In an ultimate act of faith in your abilities, and a profound respect for the fact that the last step of creation is relinquishing of direct control, you turned it loose and walked away.

The Codex prompts organisms to evolve genetic exchange mechanisms including bacterial RNA swaps and sexual reproduction in complex organisms. And maybe later, crazy stuff puny humans have never thought of (spoiler alert ;- )

Eyes are super useful. The Codex nudges each branch of evolution to evolve eyes (eyes actually evolved independently on earth many times). Your nudge factor helps ensure balanced and stable ecosystems (vultures evolved independently many times because apparently they're a useful balancing factor).

You're using the natural processes of evolution to evolve novel and interesting variations along the lines of your ideal template (yourself). Rinse and repeat on every world in the goldilocks zone in the galaxy. Bam, bipedal, self-aware, hominids will emerge throughout the galaxy.

Oops, you just asked for one planet. Sorry, I god...excuse me GOT carried away.

• In the case where there's already life there you'll have to encode your Codex into a virus which can insert the code into the DNA of one or more species. – jorfus Sep 12 '16 at 18:34
• this reminds me of the idea of a "Universal Migrator" from the band Ayreon, definitely worth a listen! – skeletim Sep 13 '16 at 18:09

Nanites - tiny robots that are the scifi fad right now.

Vial 1 contains the DNA of a million people. The DNA is housed in single celled organisms whose sole purpose is to store DNA. Additionally, this vial contains a chemical based "activator", that will, on contact, activate inert MESH nanites.

Vial 2 contains cell blanks - akin to stem cells but having nothing to instruct them how to grow. Additionally, this vial is full of microscopic MESH nanites, powered down and inert.

Multi Energy Sourced Healing nanites are microscopic robots capable of maintaining and repairing biological cell structures based on the raw DNA of the host. The DNA provides the coding sequence required to map the organisms cellular makeup.

MESH nanites can even create new life from blanks, once a DNA sequence is obtained. The technology has been known to lengthen an organisms lifespan almost indefinitely. They are able to draw power from light, from chemical reactions, or from the host organism. MESH nanites are also capable of maintaining each other as well as canibalizing "dead" nanites to build new nanites. But eventually, attrition will win the day unless the nanites are replenished with new units every couple hundred years.

• While this is very creative and entertaining, it doesn't really fit the narrative. In my world, humanity is not that advanced, they are hardly able to create a space-worthy vessel in time to avoid their demise. – Matthew Goulart Sep 12 '16 at 18:12
• It's your story, but if humans can barely travel from A to B in space, I sincerely doubt they've cracked the human genome to the point primordial goo A+B = human, even given the cook time of millions of years – Steve Mangiameli Sep 12 '16 at 18:41
• Your thinking from a real-life standpoint. Perhaps instead of transistors and similar discoveries, the history of MY humanity has been mostly of biological discoveries. They are much more evolved in biology than they are in electronics or other fields. – Matthew Goulart Sep 12 '16 at 18:43
• Hopefully you can "flesh" that world out ;-) But many of the biological breakthroughs we have today were made in large part to electro and computative breakthroughs. It's realllllllllly hard to decode DNA without a computer and run the types of simulations that enable us to reason what may have happened "way back when". – Steve Mangiameli Sep 12 '16 at 18:48
• You have a good point.... – Matthew Goulart Sep 12 '16 at 18:48

DNA won't do. Any scientific method won't do. But you are writing science fiction.

# nanobots

Humanity is going extinct? So they can't afford to be sick or die stupid death. And planet Earth is poisoned, so cancer is most dangerous mass murderer. Imagine nanobots able fix DNA. Human DNA. At least the parts we have in common.

On a spaceships they would go with simpler design. Why to put all this selection mechanisms in? They only give mass to bots. There is no non-human life on ship, nothing Greenpeace would care. So these bots are made to fix all cells that needs to be fixed. Oh, and ship has self - repairing nanobots generator. Or bots don't break easily. Or they can self replicate.

So what's happen when these are accidentally released? They find a living cell that's around proper size and try to "fix" it into a proper human cell. Most of the time, they fail. But some victims live. A bit closer to mammal. Then, a bit closer to human. It would take millennia and it would be grotesque quite often, but would work. Some organisms would develop immunity, after they acquired some human traits. Some before. And some got forcibly twisted to be humans.

• The OP states elsewhere that their humans don't have the tech to create the nanobots/nanites. However we could build off your answer and have some alien force put these nanobots on the planet before the crash to be a catalyst for evolution that acts on DNA and/or amino acid chains. The aliens programmed the bots to facilitate but not dictate evolution. Our DNA would give us a jump start on local bacteria. That could be the handwavium glue that makes it possible, as well as an opening for sequels as the nanobot evolved humans search for their ruined home world and/or the nanobot creators. – Erik Sep 12 '16 at 20:28

The tricky part is that human beings are very complex, and very finicky about their environment. As noted in answers to your previous question, there's no simple way to go from a bit of DNA to a full-grown human without some serious future-tech machinery. And since you noted that your humans are barely capable of starflight, they probably can't create living humans just from their DNA, much less having it happen by accident.

So, if we can't rely on something that exists on the human ship, let's assume our solution comes from the planet itself. I'll go with the weaker part of the question (habitable planet with simple life), since it makes everything else a bit more plausible :)

The human ship was an Ark. It contained samples of DNA of many of Earth's life forms, selected specifically in an attempt to recreate an Earth-like ecosystem (of course, a much simpler version of it). Plants to capture carbon dioxide, water and sunlight in Earthly sugars. Bacteria and algae to produce the main source of oxygen, and seed the oceans with nutrients. Another bacteria and funghi to create a soil cycle. The bare essentials to produce a world that's habitable for humans. As a part of this, a bunch of seed environments were ready on the Ark, to kickstart the whole thing, and cryo chambers to let the supervisors manage the project over the scope of many human lifetimes. Sadly, the ship crashed, and everyone on board has been killed. Well, everyone, except for the seed environments - and the primitive Earth organisms get sprayed all around the Planet. Most of them survive, and replicate - it so happens that they are much better at what they do than all of their native competitors. The environment starts filling with Earthly sugars, amino acids, fats, proteins... easily accessible raw materials, which happen to not be compatible with the existing Planet life.

The Planet life is rather primitive in Earthly terms. They have many similiarities, but aren't able to process Earthly proteins and fats at all, and even the sugars give them trouble. DNA is too stable to be broken apart by the locals. And as the ecosystem quickly (over thousands of years) becomes dominated by Earthly "raw" materials (remember, the Earthly life is much better at processing material and sunlight, and easily outcompetes the locals), Planet's indigenous life is in jeopardy, as its entire food supply starts to quickly disappear. Many of the locals tried to digest the Earthlings, but with no success - leaving the invaders inside the cells and bodies of the locals, neither being able to consume the other. Ultimately, it only served as a way to spread the Earthlings further. Until...

Finally, under just the right environmental conditions, a small portion of the indigenous population managed to break through the cells of the invaders. The two organisms effectively merged together - their cell boundaries broken, the locals enslaving the Earthlings to produce energy for them (it so happens that both the Planetians and the Earthlings use ATP for cell energy transfer), to hijack on their ability to process Earthly materials, and to more effectively capture sunlight. A tiny portion of the local portion manages to unwrap the invader DNA in just the right places, to use the invader ability to break down and synthesize proteins, and a tiny portion of those manage to incorporate the cell organelles of the invaders in their own cells. The tiny population quickly spreads all over the planet - while it's not much better than the invaders, it can at least fully exploit food sources of the invaders; keeping close check on their own genetic information, while preserving the useful bits from the Earthling's. Since they only use rather small portions of the Earthling genetic code, there's significant pressure to avoid replicating the "unused" bits, but it is more than counter-acted by every tiny trick that is found in the previously unused bits. Most of the time, the random unwrapping results in waste, or even in the death of the organism - but as the new tricks improve the adaptability of the locals, they quickly grow in number. The result is a somewhat pruned genetic information of the Earthlings, taking over more and more functions in their "host" organism. And then...

The DNA vials from the Ark start leaking. The locals, ravenous for any new Earthling genetic information, start absorbing the information, replicating it with them as they always do, trying many different ways of unwrapping it, and unlocking the processes described in the information. Predictably, this is met with little success - it's very unlikely that you'd get a viable organism just by randomly trying to execute various parts of their genetic code, even when most of yourself has already transformed to something very similar to Earth life. But while the chance is tiny, it isn't zero. And finally, it happens - the right kind of mixed local-Earthling happens to unlock the right part of the "stolen" DNA... and result in horrible outgrowths, nothing like the locals have ever seen - the Earthly processes using all the infrastructure of the surrounding local cells to spark the beginning of Earthly plant life, sprouting as grasses and funghi and bushes and trees...

The local meta-cells are quite adaptable, working with many different kinds of Earthly DNA. Most of the time, the synthesis fails, but the invader's DNA usually stays the same throughout, giving many chances at repeated attempts to recreate Earthly life. More and more complex life starts getting hold, relying on their host Planetians to spread their kind before their own replication have a chance of working. The relationship is quite symbiotic - even as the different kinds of symbiotes start devouring each other, funghi reclaiming the dead (and sometimes not so dead) bodies of the plants, Earthly soil bacteria finally getting all the nutrients they need, fixing more and more nitrogen and other nutrients in the soil, quickly spreading more and more advanced life forms all over the Planet.

Even plants are a huge stretch of imagination, the conditions for a creation of a viable seed-organism being extremely unlikely. But there's trillions of the native meta-organisms, each trying with their own copies of Earthly DNA, merging together in huge colonies in an effort to produce a viable Earth-organism, and they do have the plans - they just have to find the right conditions, the right sets of instructions to execute in just the right way, and over time, it happens, and enriches the environment. Eventually, there's enough of Earthly species to start reproducing on their own, spreading in a race for diversity to cover all the ecosystems of Planet, creating thousands of new species. And then...

Come the insects. The native meta-organisms don't stop trying, keep reiterating over the absorbed DNA, mix together with other organisms, Earthly and local, and eventually, manage to build a functioning reproductive system in a meta-plant, capable of producing insect younglings; not quite like they would be in their natural environment - with no adults to take care of them, they rely on their home-plant for shelter and food, until they are fully grown and capable of raising the next generations, and producing viable reproductive individuals, which quickly spread all over the Planet - some still clinging to their home-plants, while others are barely different from their Earthly brethren.

But while much more complicated than anything that came before, the conditions to grow a mammal or a reptile from "scratch" are even more so. While everything necessary to create the organs is in the genetic information, it's mind bogglingly unlikely they would be executed in combined in just the right way to produce the necessary environment. It's quite unlikely that there would be enough of the original DNA left, given how much of a waste it is to replicate large swathes of information that is never used - but then again, the same is true for our own junk in our own DNA; full information survives, just because the random changes to make the information shorter are very likely to break the parts that are necessary. It finally happens - home-plants with full blown wombs and egg-production-facilities, relying on their newly formed animals to spread their own seed.

The first humans are rather troublesome. They are huge, requiring lots of nutrients to grow. When they leave their reproduction chambers, they are all but hopeless - and the meta-organisms have no way to help them; there's no way to use the information they have to help with the maturation of a human. Still, many human-plants survive, by using the babies as carriers of their seed, the "fruits" becoming popular enough with the "predators". But by then, simpler mammals have already proliferated enough. And mammals have this weird connection, the "cuteness" factor, which works quite well accross species... simpler species nurturing the more complex ones, which in turn become populous and ready to nurture even more complex ones... all the way to the wolf that takes care of the helpless human twins, nurturing them and caring for them until they are themselves capable of taking care of their own (from other human-plants), forming a symbiotic relationship with the wolves that would last for ages - becoming surprisingly strong as they mature, something that Planet has never seen before...

... and thus Rome is born.
`

Note

I wouldn't call this the hardest sci-fi around. There's nothing here that would be outright impossible, but it's incredibly unlikely that something like this would happen. There's a lot of points where you deal with fragile things that survive against all odds - the DNA not deteriorating before it gets used, not being pruned by the natives, the fact that none of the local populations started becoming dominant as something else than the meta-organisms that recreate Earthly life...

But it should be quite enough to support an entertaining story without too much suspension of disbelief. It gives interesting opportunities to show clashes of the local and the Earthly. There's plenty of space for interesting organisms (and especially complex symbiotical relationships, given how central symbiosis is to the whole scenario) that quickly diversified in the rather empty ecosystem.

I want to copy from my previous answer to previous variant of this question:

Human DNA is irrelevant.

If your new barren planet has no life, it has no free oxygen (oxygen is ONLY created as a byproduct of plant life).

So your two vials need to contain bacteria which can live without the presence of the oxygen - there are few such old archea surviving on Earth.

Will take you many millions of years to develop more complicated life forms. Evolution is random, there is NO GUARANTEE that plants will develop (creating free oxygen) and humanoids develop later, unless your landing vessel is capable of guiding the evolution over many millions of years.

And even then, how you say extinguish dinosaurs, allowing mammals to take over the planet?

If you want scientifically-plausible answer, you need to read up on evolution. hint: Evolution has no goal. Wikipedia is a good start.