In my up coming novel this fall, I got the human crews as well as some humanoid alien species working and living onboard a FTL starship exploring an uncharted cluster of neutron stars and black holes. As the story progresses the starship will visit strange and unfamiliar worlds and add diversity to the existing crews, I'm seeking a carbon based living organism which doesn't share our cell structure or DNA for reproduction and I also need the unique environment to sustain such a lifeform. Last but not least how can it stay onboard the vessel without jeopardizing its life?
1 Answers
The only known non-cellular lifeforms are the viruses.
A virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.
This suggests the most probable environment where a virus can exist, is inside the living cells of other organisms. This might be extended to some sort of generalized organic system. OK. A mass of organic or biological material, possibly undifferentiated, rather like a living blob or perhaps an organic pool.
The origins of viruses in the evolutionary history of life are unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria. In evolution, viruses are an important means of horizontal gene transfer, which increases genetic diversity.[7] Viruses are considered by some to be a life form, because they carry genetic material, reproduce, and evolve through natural selection. However they lack key characteristics (such as cell structure) that are generally considered necessary to count as life. Because they possess some but not all such qualities, viruses have been described as "organisms at the edge of life",[8] and as replicators.
Source for the above quotations is the Wikipedia entry on viruses.
The OP has been given references to sources of information about alternatives to DNA, in the comments above, these do not need to be duplicated in this answer.
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While I agree that viruses fit the OP's criteria, they may not have the level of intelligence or size to interact with a ship crew. Would there be a way for viruses to evolve to or reach that point? – Zxyrra Nov 05 '16 at 15:51
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1See life without cells. What you describe is known as a cell-free culture. – JDługosz Nov 05 '16 at 19:07
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@JDługosz: Well, well. Cell-free cultures are new to me. To think I only hypothesized their existence & there they are in the real world.. I really should have made the connection to a syncytium. Always something new to learn. – a4android Nov 06 '16 at 03:00
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@Zxyrra: That's why I immersed the viruses in, what I now known, as a cell-free culture. Provided it can develop sensoria and some information processing capacity (plus memory & communications channels) it should be on the way to gaining sapience. This concept gives the OP something to build on for an acellular lifeform. – a4android Nov 06 '16 at 03:03
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Re-reading my old post, I note that Needle explained the creature as decended from viruses somehow. So @zxyrra, read Hal Clement for a belevable way, written by a biochemist. – JDługosz Nov 06 '16 at 04:03
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@JDługosz Sorry, to correct you, but Clement was an astronomy graduate with post-graduate degrees in education and chemistry. He was good at sticking to scientific credibility. As a science teacher he taught astronomy and chemistry at Milton Academy. Massachusetts. One of nature's nice guys. Had the good fortune to meet him, chat about alien life in the accretion disc of a black hole & get my copy of his Best of collection signed. – a4android Nov 06 '16 at 11:39
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Another se had a big debate as to whether it was ok for math teachers to call themselves mathematicians. I guess a chemestry teacher is not a chemist, too. – JDługosz Nov 07 '16 at 04:52
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@JDługosz; Clement was enough of a scientist, by training and as a teacher, to be a science fiction writer. This doesn't make him a scientist, because SF isn't exactly science, but he was scientifically cogniscant which counts here. – a4android Nov 07 '16 at 09:48
alternatives to dna
. – JDługosz Nov 05 '16 at 09:53