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Alternative Biochemistries WIP

By thomastapir
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A rough draft of a chart attempting to tabulate potential alternative biochemistries across three different dimensions: solvent systems, structural matrices, and genetic coding methods. YELLOW HIGHLIGHTING indicates terrestrial conditions. Will scrap soon, but I wanted the initial exposure for maximum feedback. This is also available as a Word doc if anybody wants a copy to edit, correct, or append themselves.

I rarely do "true" aliens not because I'm uninterested in them, but because I find the potential for creativity so vast and overwhelming that I blanch before the challenge--and, I feel, the responsibility--of creating beings that live up to the implied originality and creative promise of the term "alien." And yet the whole premise fascinates me, the challenge fascinates me; I want to somehow shrink the problem down to a manageable size, reduce it to something I can get a handle on, wrap my hands and brains around. I want a chart defining all the potential factors involved in living systems and life-supporting environments, neatly graphed and correlated and tabulated by statistical probability. I want a table ascribing the likely incidence of different alien biochemistries to various locations based on stellar type and age, planetary proximity to sun, and distribution of resources within the galaxy. I want to be able to posit with reasonable confidence that 65% of life in the Milky Way will be organic, and that 85% of such life will be found in the "zone of metallicity" occupying the central volume of the galactic disc; that of the remaining inorganic life, 15% will be based on silicon rather than carbon, with a mere 10% exploiting a fluorosilicone solvent system and the rest taking advantage of high-temperature sulfuric acid...

I know, this goal would probably take a lifetime to realize and may very well be impossible, but it's one I can't get out of my head. These paltry charts are a very tentative first attempt at this undertaking, a tiny drop in a vast bucket, and yet even they are so far incomplete and probably inaccurate and desperately lacking in more alternatives. That's where I need the help of my brilliant and creative dA friends. What are some other alternatives to carbon? To oxygen? To DNA? What kind of life-supporting substances would go into solution (yet remain stable) in methanol, or in hydrogen chloride? (Most of the blanks on that first chart represent solvents suggested in passing by Peter Ward in his book Life As We Do Not Know It.) My text references are limited, I've pretty much exhausted Wikipedia as a resource, Google searches have been frustratingly unproductive, and even academic databases are lacking. This is the kind of endeavor that requires not just raw data but informed opinions drawing on a knowledge base I lack--and that's where I'm hoping my imaginative and better-educated friends will come to the rescue.

And there are SO MANY factors I want to address, beyond mere physics and chemistry: potential alternatives not just to the known terrestrial kingdoms of life, but to the entire domain of cellular life, like Seilacher's original interpretation of the Ediacaran "vendobionts." Even given the assumption of pervasive cellularity, I want to explore the relative likelihood of independent (extraterrestrial) convergence on terrestrial body plans. Will selection factors inevitably lead to cephalization and bilateral symmetry in motile organisms, or is the apparent fitness of this design an illusion created by its prevalence on Earth through our shared origin in a default basal template established by Hox genes ([link])? What does this say for the possible emergence of truly divergent body plans on other worlds? Will we encounter ecosystems of Wheels ([link]) and Moebius Fish ([link])?, or will morphology as we know it prevail throughout the universe...? Educate me, brainstorm with me, help me fill in the gaps and expand this endeavor beyond my wildest dreams!

75% of Sun-type stars are older than our own and therefore likely to host planets with older (possibly more "highly evolved"?) life--that's one statistic I know for sure. I want to know MOAR.

7.15.09 UPDATE:

Revised to reflect ~labgnome's ([link]) incredibly helpful input. The genetics portion especially has been significantly revised and expanded, but there are additions to each section. There are still gaps and I'm sure inaccuracies, wholly my own, which are why this is still a Work In Progress.

I also hope to do a flowchart of potential morphologies reflecting my exchanges with Dan Bensen ([link]) and ~spinery ([link]) on alternative "topologies" and "geometries" as they might apply to alien body forms.
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anonymous's avatar
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Exobiologics's avatar
There are also CeNA which include cyclohexane, borozylenes, phosphonitriles, and many more.
CaptainXenolove's avatar
I just LOVE pure, dry, merciless science when it comes to worldbuilding. Sadly this is SO super scientific, I can only understand half of it.
Well done! Totally saved that image! :*
Mechatherium's avatar
Water is so common in the Cosmos that "ammonia" may be more likely to be an ammonia/water solution. Ammonia/water solutions can remain liquid down to 173K (-100 deg. C, -148.270 deg. F).

I find Wikipedia a useful place to start research: en.wikipedia.org/wiki/Ammonia

EDIT: Hydrogen cyanide might be too reactive to be a solvent. Hydrogen sulfide might react with metabolically active minerals like iron to form insoluble sulfides, IDK.

Just my $0.02
luka1184's avatar
Very useful, thank you!!
thomastapir's avatar
My pleasure, I hope it comes in handy!
Arborine's avatar
This is dead handy, and definite food for thought - thank you!
thomastapir's avatar
My pleasure, I hope you get some use out of it!
Moriadne's avatar
This is fantastic!

Good luck on those flowcharts! Would love to see them as well!
thomastapir's avatar
Thanks very much! Man, I need to get started on those one of these days. SO DAUNTING. D :

Appreciate the feedback, I'm glad you like this!
enigmaticworld's avatar
VERY interesting... you say there is a doc version? :>
thomastapir's avatar
There is! Just note me an e-mail addy if you'd like a copy. :)
Exobiologics's avatar
What is your email?
thomastapir's avatar
Bill-Porta's avatar
I'm working on a project about an alternative biochemistry based on phosphorus and nitrogen... That will be useful and helpful :) ... Thanks
thomastapir's avatar
Sounds like an awesome project! I hope this chart does come in handy for you...Thanks for the watch and the fave! :)
Bill-Porta's avatar
SaturnineOranges's avatar
[link]

The above link goes to the National Academy of Science of the United States of America website, to an abstract entitled, "Some implications of an alternative structure for DNA" by V Sasiekharan, N Pattabiraman, and G Gupta.

Then This Link: [link]

is to the full PDF of the article.
thomastapir's avatar
VERY interesting...Thank you!

It seems like the, um, non-double-helix model would almost certainly be less compact and therefore less efficient from a biological standpoint, but the ease of strand separation would make it favorable for lab experimentation, which is I assume what they were going for. I also found it interesting that it's more energetically efficient; perhaps it's something that would be selected for under certain circumstances in nature, such as when total organism size isn't as much of a constraining factor (Jovian floaters?).

Thanks again, that's fascinating stuff!
SaturnineOranges's avatar
This is extremely interesting...

One other thing to ponder would be what brain/ganglia-analogus structures/systems alien life might have. If you consider it, the brain/ganglia-neuron model is rather complex (..although also rather ubiquitous), so the chances of it occuring again, far away, in a different environment...are low I think. So what other models could there be? If I think of anything good, and with science to back it up, I'll write something up...but right now I'm just going to file it.

Anyway, great job! :w00t:
thomastapir's avatar
Wow, that's a damn good point on potential alternate brain structures...I wouldn't even know how to chart it! On likelihood of incidence, I tend to think that the integration and coordination of sensory input (assuming "senses" and "input") will be of such an overwhelming evolutionary advantage that it will tend to be selected for rather than not, at least in motile organisms playing a part in any kind of producer/consumer ecology resembling our own. What form that neural "complexification" might take is a whole 'nother can of worms...I've heard suggestions ranging from solid-state "bioelectronics" to tubulin molecules acting as quantum waveguides. In the organic realm, I think it would be intriguing to look at what aspects of neural complexity may have evolved independently in multiple lineages on Earth--if any. Might be a good indicator of evolutionary fitness, providing a model to apply to non-terrestrial organisms.

Thanks for the great feedback and the fave! :thumbsup:
whalewithlegs's avatar
Wah, once again I'm trying to look at this seriously and can feel the valves in my brain shutting down in rapid succession. I tend to approach things from the, "If it exists, we can explain it" platform, which is basically what I think good half of 'real' science is anyway :p

Biology does open some of the canal locks though ... DNA varieties & alternatives! I hadn't looked into that sort of thing before!
thomastapir's avatar
Hey, no pressure or obligation to master the nuances of molecular biochemistry in the week before you move to Taiwan! Or ever, for that matter. Like I say, I just put this out there for people to take whatever they can get from it, and also from the selfish perspective that I was fishing for knowledgeable friends to fill in some blanks and correct some mistakes. Which several people did. :)

Oh man, I totally hear you on the "if it exists, we can explain it" model of scientific exploration. I think it's the basis of all good science--letting the natural world explain itself to us, and finding means to understand what it's saying. Unfortunately the public perception of science has been distorted into this Frakenstein monster where people tend to believe that Scientists sit around all day dreaming up obscene, half-baked theories to further corrupt the moral fiber of our youth. The state of scientific ignorance in our country especially is absolutely appalling...But I guess that's a rant for another day. :)
anonymous's avatar
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