In my world, the characters have to travel to a new planet and start all over again. Say they make the journey in a space ship transporting a bunch of human DNA samples. If this ship crashed on the new planet, everyone died, and the DNA "leaked" onto the surface, could anything come of it?
Just DNA? Probably not.
DNA in and of itself is just information. It contains the coding for cellular machinery, it is not that machinery itself. In the case of a crash landed ship where all humans have died but left the hull largely intact, then all the bacteria, microbes and fungi would spread out from the hull and start populating the planet. Give it a few billion years and there might be human like things walking around again.
There are some bacteria on Earth capable of transformation. They can take up DNA from the environment and incorporate it into their own genome.
When such bacteria also exist on the alien world, they might end up with traces of human DNA. When these bacteria then evolve into higher lifeforms over the next millions of years, traces of the human DNA might still be detectable in them. It is very unlikely that the resulting lifeforms will have any obvious resemblance to humans. But when someone analyzes their genome in a lab, they might be surprised to find a few genes usually only found in humans.
Consider how much infrastructure a human being needs to survive and grow up before it gets self-sustaining. Even if you had a cell to begin with (more than just the DNA), you would need a womb, a mother to take care of the child as it develops, supply it with nutrients and teach it to survive, and maybe in a few years you'd have a working human. Your scenario is more ridiculous than expecting that a bit of your dead skin would come to life as another human :)
If you want an analogy, it's kind of like expecting that if you throw a floppy disk at the ground which contains a Word document, it would get printed on sheets of paper. You're missing all the machinery required to make that happen.
You are essentially asking if abiogenesis (life arising from non-life) could be catalyzed by the addition of DNA. The answer is we don't know, because we aren't sure how abiogenesis works.
It definitely might help though. Most models of abiogenesis start with the creation of organic building blocks, such as nucleic acids which make up RNA and DNA. Then these building blocks arrange themselves by chance into some sort of self-replicating polymer. This then begins the evolutionary march as those self-replicating chemicals mutate and procreate. A big influx of organic building blocks in a concentrated area, if the conditions are near perfect, could kickstart the beginnings of life. But, it is a long shot.
One note is that DNA is actually not that great at forming self-replicating polymers and it is widely believed that the first life on Earth was based on RNA because it has better catalytic capabilities. You can read more about it here. So it may not actually be the DNA from your humans that begins life on the new world, but rather the RNA.
mad genius scientists which planned the colonization mission came to the conclusion that those colonists who volunteered for the mission might be great for flying through space and building a colony, but would be unworthy to be the genetic base for the new human population. They picked a number of far more capable specimens of mankind. But how would they spread their DNA to the planet?
They came up with a devious plan: They bio-engineered a new retrovirus. A retrovirus is a virus which latches on to cells and replaces their genom with its own. But their retrovirus had some modifications: It carried the DNA of the "worthy" humans, and it only targeted human egg and sperm cells. They filled a vial with that virus and planned for it to burst after landing on the planet. The idea was that all the colonists would be contaminated with the virus and all their children would not be their own genetic offsprings but those of the chosen people.
They expected that it would take the colonists a couple years to notice that all the children born on the new world have no genetic similarity with them and then at least a decade until they found the reason and purged the retrovirus. But until then there would be plenty of retrovirus-children around and disowning them would be both immoral and impractical. So the children would assimilate into the society, have children themselves and carry on the "superior" genes.
Unfortunately nobody will ever know if that plan would have worked because those genetically inferior colonists couldn't find the "activate parachute" button in time.
But curiously that retrovirus worked too well. It didn't just work on humans but also on the local fauna of the planet. So all creatures around the crash site started to become pregnant with human babies. Most of those embryos would not survive gestation in an uterus designed for a completely different species. But there was one species which was for some crazy coincidence biologically compatible enough with humans to give birth to living human babies and socially compatible enough to keep them alive during infancy.
Note that especially the last part is very unlikely, so it will require quite a lot of handwaving.
Everyone died in the crash - but millions of species of bacteria in the bodies, food system, and on rocket surfaces survived? Most of them require oxygen for life (which is not yet present on your new planet) but few do not, and those will take over the planet.
In few billions of years (and with some luck) you will have more habitable planet.
The vial with DNA is 100% irrelevant, especially if it is human DNA.
To improve your chances, and speed things up, you should aim to sending an fully automated rocket which will orbit the planet for few hundred millions of years and send down (soft landing, not burning on entry) capsules with bacteria needed for next evolutionary step: anaerobic bacteria first, then some algae to produce oxygen, later some hardy multi-cellular organisms, to give evolution some shortcuts.
Luaan is utterly correct in his/her assessment, as DNA is only a set of instructions that encode a design. If a womb were not available, then the theoretical minimum that would be required would be an artificial womb, equipped with an artificial connection to the umbilical chord (starting at a microscopic scale), accompanied by an artificial input of blood, into which would have to be added a regular, frequent supply of nutrients (in a manner equivalent to what is provided by a stomach) - plus a constant supply of oxygen via the very same route.
Even were all the above possible and successful, and the resultant child were successfully 'born', it would then need constant nuture in the form of artificial feeding, cleaning, protection, nurturing and training.
Seeing as all of the above are outlandishly far-fetched, the bare minimum requirement would in reality be one human being aged around 8-10. And it goes without saying that male and female would be required for there to be any continuation.
As for abiogenesis, that is even more far-fetched than the above scenario. Non-animate materials remain non-animate materials that decay, in line with the second law of thermodynamics. Life requires an intelligent blue-print (which is what DNA represents), along with a suitable environment, plus an ability to survive and reproduce.
DNA alone, certainly not. However, a vile full of single cellular organisms (complete cells) certainly could survive as long as they were able to adapt to the environment.
A multi-cellular organism generally requires a parent for birth and nurturing. However, this does not have to be the case. It could be possible for an advanced culture to create a stem cell which would grow up on its own into a multi-cellular creature without the need of a parent. I can't think of a creature currently in existence which has this ability.
Presumably, the goal was to repopulate to begin with, so if we assume the DNA collection is transported via live retrovirus (DNA sequence encoded in RNA, once the virus infects a host, it starts reproducing from the DNA it is programmed with) AND that there is already life the virus can infect, AND that some of that life is malleable enough that it doesn't die upon infection, but gets assimilated by the virus (highly unlikely)... etc... Then sure it is possible some new life could emerge. It won't be human though.
It would be like rolling the dice a gazillion times twice, and hoping the sequence of results would be the same.
In 1951, a researcher took a cell sample from a cancer. These cells have mutated into a form that is independent of the human body, they live and thrive on their own. (Well, at least in laboratories)
This cell line is called HeLa from the name of the patient.
It is much used by researchers since it grows easily and is still almost genuine human cells.
If the spaceship laboratories had samples of HeLa they could very well escape after a crash. On an otherwise unpopulated planet they could survive and even thrive.
Of course, the chance of these cells evolving back into something humanoid is slim. Even if you have all the genes you would have a severe chicken/egg problem, or rather a human/womb problem.
Still, if a future researcher were to come to this planet and take samples of the local life they would be severely puzzled.
- Due to wind patterns and the spaceship's weight compared to the local sand, the spaceship sinks deep under the surface and becomes unfindable without high-tech tools. That protects it from UV and looting for a few thousand million years.
- During the crash, moss/acarian/other tiny life forms were peppered on the planet's surface, where some started striving.
- Two thousand million years later, this life has evolved into intelligent creatures (the Zorglubs) who spend their days studying cloning and biotechnology.
- Despite their lack of interest for underground exploration, the Zorglubs finally find the buried spaceship, and quickly understand what the samples are (even in their now-fossilized state).
- As they always do with all fossils they find, the Zorglubs clone each DNA sample, creating a collection of humans.
- The Zorglubs put these humans in the planet's zoo, where they entertain young Zorglubs for generations.
No. But a colony ship doesn't just carry DNA.
Instead it would carry a selection of biotech to terraform the planet. This is going to realistically take 1000s if not millions of years.
The ship might first sterilize the planet with something akin to nuclear weapons, then release life forms adapted for the streilized environment. Layers of later life forms would be designed to survive in the environment generated by the previous. You'd have an oxygen catasrophy, release more complex animals, complex life forms like lichens that can break down the surface and generate soils, etc.
Each epoch would be designed to thrive in the environment predicted to be generated by the previous epoch. Possibly to make the situation work more reliably, a sterilization period (nukes) would occur to "clean slate" the world and prevent adapted previous-epoch creatures from out-competing the new-epoch creatures.
Once the world is reasonably terraformed, multicellular plants and animals can be created. When a functioning macro-scale ecosystem exists then it becomes safe to add humans to the mix.
An alternative to the nuke-and-reseed approach might be to use viruses to guide evolution. You could imagine a high-tech civilization which knows of various novel "keyhole" strategies unlikely to be invented or defeated by greenfield organisms.
Use those to create viruses, and release said geneengineered viruses to cause expected existing lifeforms to evolve in certain directions.
But that seems harder.
It's impossible to say for sure.
The manifestation of life and its evolution are quite possibly, a predominant byproduct of chaotic chance & data, to the power of billions of years. However, (from reading your comments), I think what you're looking for, is a fundamental scientific concept, known as falsifiability.
Falsifiability or refutability of a statement, hypothesis, or theory is the inherent possibility that it can be proved false.
A statement is called falsifiable if it is possible to conceive of an observation or an argument which negates the statement in question.
Falsifiability | Wikipedia, the free encyclopedia
https://en.m.wikipedia.org › wiki › Falsifi...
What does it mean for something to be falsifiable?
Falsifiability or refutability is the logical possibility that an assertion could be shown false by a particular observation or physical experiment. That something is "falsifiable" does not mean it is false; rather, it means that if the statement were false, then its falsehood could be demonstrated.
Falsifiability | Princeton University
https://www.princeton.edu › tmve › docs