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As we continue to search for life in very different environments than the earth, it would make sense to me to think about and design lifeforms (theoretical) that could work in these environments. I know that we are searching for life in extreme environments, but are we thinking about lifeforms that could have evolved in such environments? (Even if we dont find any)

The idea of the atom comes from ancient greek philosophers long before one could find any evidence for it. Although their views on what atoms look like and how they behave were incorrect, one could later refine this model through evidence and experimentation.

I think some good thought could makes us learn what to look for in the first place.

Is this still just a field that science fiction thinks about, or are there any serious publications on this topic? If not, why not?

Clarification: I mean the theoretical design of lifeforms. Not just manipulating and editing existing lifeforms, I mean designing completely new theoreticaly plausible lifeforms, within the constraints of a given environment. On paper or simulation etc, not actually making them physically.

If you find any scientific papers on how and what kind of life could exist for example on Titan, Europa, below Earths crust etc... or any other environment, please link to them in your answer. Thanks!

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  • $\begingroup$ What is your definition of "new lifeforms"? You said without the use of existing life forms so you mean to synthesize a new strand of DNA as a genome (by selecting some genes you want to be present in the "new" organism" and then let this grow or what? $\endgroup$ – KingBoomie Feb 12 '17 at 22:02
  • $\begingroup$ No, I don't mean anything physical. Just thinking about what kind of life could exist. $\endgroup$ – macco Feb 12 '17 at 22:09
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First, you can check out this Wikipedia entry: Hypothetical Types of Biochemistry. I caution you that the scientific utility of many of these hypotheses isn't great since they are, at least currently, untestable.

Second, your question brought to mind some current research by two groups of scientists in the field of synthetic biology which may, in some way, answer your question. I will briefly mention these below.


Scientists are attempting to create synthetic organisms with minimal genomes (those in which every gene is essential). In one of the more recent studies (Hutchison CA, et al. 2016. Design and synthesis of a minimal bacterial genome. Science.), they randomly knocked out genes of an organism and then, based on survival and growth, classified them as essential, non-essential and quasi-essential (deletion results in growth impairment). They were then able to pare down the genome to 473 genes, which they claim "has a genome smaller than that of any autonomously replicating cell found in nature".

Important points from this research with respect to your question:

  • Of the 473 genes in the organism described above, 149 have an unknown function. In other words, we still have a limited understanding of what exactly is required for the basic biochemistry of life on Earth. To quote the article:

    ...biological functions could not be assigned for the ~31% of the genes... Nevertheless, potential homologs for a number of these were found in diverse organisms. Many of these genes probably encode universal proteins whose functions are yet to be characterized.

  • Additionally, before their knockout approach described above, the researchers attempted creating minimal genomes by rational design. Note that this is not designing new organisms but rather deleting genes from an existing genome based on whether they are thought to be essential. They failed. Quoting a press release (emphasis added):

    [The researchers] initially formed two teams, each with the same task: using all available genomic knowledge to design a bacterial chromosome with the hypothetical minimum genome. Both proposals were then synthesized and transplanted into M. capricolum to see whether either would produce a viable organism. “The big news is we failed,” Venter says. “I was surprised.” Neither chromosome produced a living microbe. It's clear, Venter says, that “our current knowledge of biology is not sufficient to sit down and design a living organism and build it.”


In another avenue of research, scientists are attempting to create synthetic cells based on self-replicating RNA and compartmentalization by spontaneously forming fatty acid vesicles, perhaps somewhat plausibly mimicking how life may have arisen on Earth. Of interest to you may be this review (Blain and Szostak. 2014. Progress Toward Synthetic Cells. ‎Annu Rev Biochem.) which, in their words:

[focuses] on bottom-up approaches to the construction of artificial cells from molecular components or subsystems. We do not discuss the top-down approach of systematically removing genes from extant organisms to achieve a minimal genome, nor do we consider the creation of new types of cells by genome synthesis or extensive genome editing.

They say in the article (emphasis added):

In vitro translation systems have successfully been incorporated into vesicles, resulting in the efficient synthesis of proteins... However, replicating the entire system, including DNA and RNA polymerases, transcription and translation factors, transfer RNAs, the ribosome, and other components, is still a distant goal, and proposals to do so involve more than 100 genes. Properly coordinating the replication of such a large synthetic system may require additional regulatory components.


Take away message: We are not yet able to design or create, de novo, living organisms based on known biology, let alone organisms based on some hypothetical biology of another planet.

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  • $\begingroup$ Interesting answer +1! But I just want to draw your attention to this line I mean the theoretical design of lifeforms. Not just manipulating and editing existing lifeforms, I mean designing completely new theoreticaly plausible lifeforms, within the constraints of a given environment. On paper or simulation etc, not actually making them physically. to which only your last paragraph seems relevant. $\endgroup$ – another 'Homo sapien' Feb 17 '17 at 5:02
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    $\begingroup$ @another'Homosapien' Thanks. The point I was trying to get across is that people are trying to design synthetic life within the framework of known biochemistry. However, they haven't succeeded. Given that, how could we possibly design organisms with an entirely new and made up biochemistry for life on planets that we know almost nothing about? $\endgroup$ – canadianer Feb 17 '17 at 7:47
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    $\begingroup$ Also, I want to emphasize that it is leading researchers in the field that are saying we don't possess the knowledge to design and build a living organism, and the ability to do so is far away. $\endgroup$ – canadianer Feb 17 '17 at 8:09
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The answer to this question can go as far as anybody's imaginations. So I'll just tell why the answer is what it is, and try to include scientific facts (possibly with references) wherever possible.

Simple Answer: Designing alien life forms on the basis of current theoretical and practical knowledge of science (if this is what you mean) is still, and seems to remain, a field of science fiction only.

Why? Because, simply, the proposed organisms can be as many as you can count. The point is that, even if this field comes under the category of science, it will remain as large as the universe itself, because there are literally no boundations and limitations to speculation and imagination. Only recently have researchers agreed that discovering organisms similar to humans is much much less than any layman thinks. Actually, there is even a formula for it, known as the Drake equation after Frank Drake who proposed it. The equation is:

$N = R^* \times f_p \times n_e \times f_l \times f_i \times f_c \times L$

where:

  • $R^* =$ the average rate of star formation in our galaxy
  • $f_p =$ the fraction of formed stars that have planets
  • $n_e =$ the average number of planets per star that can potentially support life
  • $f_l =$ the fraction of those planets, fl, that actually develop life
  • $f_i =$ the fraction of planets bearing life on which intelligent, civilized life has developed
  • $f_c =$ the fraction of these civilizations that have developed communications i.e. technologies that release detectable signs into space
  • $L =$ the length of time over which such civilizations release detectable signals

Obviously, this answer comes out to be very small, meaning that intelligent life is very difficult to find. But that doesn't mean finding life is difficult. And this claim gets even more support when scientists find water on mars and even mercury! Now, to give a bit of knowledge, this field is not really limitless; there are (at least) two limits (i.e. I'm not including more). The first limit is source of liquid water$^*$. Now, knowing that water is easy to be found almost anywhere, this does not seem quite a difficult one. Another one is source of energy. Now this is a difficult one. The problem with discovering life (in near future at least) is the area in which we are searching. Most of the searches (by telescopes of course) are being conducted near red dwarf stars. There are quite some reasons for it:

  • red dwarf stars are quite stable
  • they have very long life
  • they are pretty less shiny (making observations easier)
  • they may be home for many super-Earths

But being less shiny also poses a problem: too less energy for life. Red dwarf stars emit most of their radiation in the infrared portion of spectrum, which is pretty useless for plants (on Earth at least). Now, to survive in a red dwarf system, plants need to capture infrared light. Thus, the speculated plants in red dwarf systems will be pitch black just to absorb more energy. Also, red dwarf stars are pretty lightweight, as less as 7.5% of sun. This means they have less gravitational pull i.e. they will have much lighter planets in their Goldilocks zone. Now, much lighter planets means much less gravity on planet's surface. Thus, the speculated plants in red dwarf systems will be a lot higher than plants on Earth. But, less gravity also means much less density of air even on surface. Now, you can interpret it yourself. And, not just to surprise you, there would be absolutely no surprise if in future a satellite discovers silicon-based life, because it is really possible for life to emerge from silicon instead of carbon!

$^*$why I am continuously saying liquid water has a reason. Water is actually one of the very few candidates that can serve the purpose of maintaining life forms. Its one of a handful of liquids which are liquids at desired temperature. As one might think, life cannot survive below a certain temperature, simply because below that temperature, the liquid itself would absorb all the metabolic heat from organism and evaporate. So, it is quite relevant to say liquid water here.

What I meant to say is that there are technically no boundations to designing alien life forms, as long as you talk about the whole universe. So, this does not really count as science. After all, if you search science definition on Google, you get this:

the intellectual and practical activity encompassing the systematic study of the structure and behaviour of the physical and natural world through observation and experiment.

This does not include imagining alien life forms in any way. So, I do not think this subject would ever be considered as scientific by the scientific community. Mostly, scientists are not indulged in this kind of work because they like to observe and interpret natural phenomena rather than imagining them. Scientists make laws from nature rather than applying laws on nature. Still, there are some scientists who take this matter seriously and publish scientific papers about it. I could find only one (PDF) related to this point. You might get some more on the internet.

In the end, if you think about how plants would look on a planet in a red dwarf system, you might end up with this:

life in red dwarf system

Bonus: Dawn space probe from NASA has detected organic materials on Ceres(!) Now, what kind of organisms would you expect to see there based on our current knowledge about Ceres?

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  • $\begingroup$ "What I meant to say is that there are technically no boundations to designing alien life forms, as long as you talk about the whole universe". However if you consider only one environment (for example the moon Titan) you already get a lot of limitations. Do you know of any scientific papers that consider these limitations and try to come up with various possible lifeforms that could survive in such an environment? (Also note that you don't absolutely need water for life, you probably just need some kind of solvent that behaves in a similar fashion) $\endgroup$ – macco Feb 13 '17 at 15:50
  • $\begingroup$ Why are scientists not interested in these things? This seems rather odd. If you find any good scientific papers please add them to your answer. $\endgroup$ – macco Feb 13 '17 at 16:01
  • $\begingroup$ Thank you for a good answer. I will award the bounty to the best answer at the end of the period. I am very interested in this and the more diversity I can get with different answers the better. $\endgroup$ – macco Feb 14 '17 at 11:36
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Is there a biological field for designing life?

The field is called synthetic biology. It is a very new field. With not many player. Currently being constructed is a synthetic yeast Sc2.0. There is attempts to get interest and funding for a synthetic mammalian genome. The synthetic human genome HGP-Write.

More serious work is adapting life to do something. Stuff that we are more familiar with like GM crops. De horned cattle. Better race horses. etc

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