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Could we eat an alien life form?

  1. Aug 26, 2011 #1
    Yes, I know that it should be found and hunted (harvested?) first. ;)

    Let's take assumption that's a carbon based life form using water as solvent.

    Are the aminoacids that we use the only feasible and convergent evolution would cause that they would have the same? What would be a reaction of human organism for facing mostly the same set but with a few different aminoacids? Would they be also absorbed in digestive track? If they were would our organism be able to decompose them harmlessly?

    How hard would be chirality to cope with? Could mirror version of known compounds be at least used as source of energy?

    Should immune system react agressively for such unknown compounds?
  2. jcsd
  3. Aug 26, 2011 #2


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    This is a near impossible question but if I had to stake a claim I would say no. You're question doesn't just assume that the alien life uses carbon and water but also that it uses the regular amino acids, phospholipids, carbohydrates and nucleic acids we are familiar with. If they do then we are in even bigger trouble from infection by organisms we have no immunity against. If they don't then we are either going to be poisoned or have superantigenic reactions.

    EDIT: Was in a rush when I first posted this and forgot to mention a few things; firstly it seems unlikely that evolution on another planet would give rise to lifeforms with similar biochemistry to us (just google alternative biochemistries for an idea of how many options we've only hypothesised). Secondly even if they have similar biochemistry, so what? All life on Earth uses the same biochemistry but we can only eat a small part of it without being poisoned, infected or malnourished.
    Last edited: Aug 26, 2011
  4. Aug 26, 2011 #3
    I'm somewhat uncertain about the risk of being infected by an unknown microorganism. Would it be a case where that would be more a problem for a pathogen to be compatible with its host and not vice versa? Is known any case where pathogen was able to attack us that wasn't normally attacking target as simmilar to us as at least vertebrates?

    And what with the less speculative part? Can we metabolise an unknow aminoacid or compound with mirror chirality?
  5. Aug 26, 2011 #4


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    You're right it is highly unlikely we would ever get an infection, but you proposed an incredibly similar biosphere. As for the rest IIRC we do metabolise different chiralities of amino acids but I don't remember which one. As for unknown that would depend on what it was and I doubt we could guess without testing.
  6. Aug 26, 2011 #5
    A Pathogen that has not evolved to infect us would have less chance of doing so... Same as if an organism which had evolved in a particular environment was removed and placed in an entirely different environment, the organism would not do as well... at least in the first generations.

    As for a known pathogen that doesn't attack vertebrates attacking humans, I'm not sure.

    The only problem I see for eating an alien is the issue of poisoning... because there are plenty of organisms that have evolved in environments that are different to the human body that produce compounds toxic to us.
  7. Aug 26, 2011 #6


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    (Quote taken from thread name.)

    I bet I could eat 100.

    Joking aside, on a very basic level, we associate eating with getting caloric energy. This is dependent upon proper chemical digestion. The symbiosis that evolved in the food chain here on Earth would not be a "given" over interplanetary distances.
  8. Aug 26, 2011 #7


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    If you can't, don't feel badly about yourself. With my special training program, anyone can eat 100 aliens in 7 weeks.
  9. Aug 26, 2011 #8


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    Well, I certainly applaud anyone wanting to eat 100 alien life forms, but take it from this exobiology rat, I've spent my entire adult life at the alien snack bar, and a program like this one can do more harm than good.

    If you only eat from one exo-planet (and that's all eating food like alien life forms is going to do for you), you're setting yourself up for injuries down the road. I've seen it a hundred times.

    Eating alien life forms basically only train the gut muscles and to some extent, the esophagus. What you really want to do is train your entire digestive system, all the major gut groups (esophagus, stomach, colon, liver, and kidneys) at the same time, over the course of a alien meal. And don't forget your dipping sauces!

    I'm proud of you guys wanting to do this. Three marklars! Falling in love with eating aliens, eating right, etc., is one of the greatest things you can do for yourself. And you WILL fall in love with it if you can just force yourself to stick with it a year or two and experience the amazing progress you'll make.

    But do it right, okay?

    My advice, find a good alien nutritionist, with qualified trainers who will design your programs for you (especially in the beginning, until you get the hang of it yourself) and guide you in your quest for alien nutition. Thirty to 45 minutes a day, three days a week, is all you'll ever need to do (I refuse to believe anyone is so busy that he or she cannot make time for that, especially considering how important it is).

    And don't worry about being embarrassed or not being in infected with something horrible the first time you walk into the alien restaurant. You have to start somewhere and almost every one of us were there ourselves at one time. So no one will say anything to you and very, very quickly you will progress way beyond that stage anyway.

    Now get out there and do it! :-)
  10. Aug 26, 2011 #9
    The closest thing that I could think are stereoisomers of vitamin E. Part of stereoisomers still retain function (a bit weaker) part not at all.
    I was curious whether there were any experiments in which ex. were used artificial racemics mixture of known organic compounds or something like that? (that would give a hint how organism can deal with with wrong chirality. Any ideas?
  11. Aug 26, 2011 #10
    Only if you stuff it with cheese, wrap it in bacon, and deep fry it.
  12. Aug 27, 2011 #11
    Seeing how easily cross species transmission of viruses occurs on earth, it wouldn't be too surprising to see virus like particles infecting humans before we develop any immunity, artificial or otherwise (assumign conditions very similar to those on earth like you said).

    Digesting is not a problem, but as far as making proteins is concerned, only l-amino acids will do. However the reason for this homochirality is not exactly known.
  13. Aug 27, 2011 #12
  14. Aug 27, 2011 #13
  15. Oct 23, 2012 #14
    But what if we do a Futurama and think we're eating a small life form with no pain (because it isn't reacting) but it turns out to be the spawn of a rather aggressive mother alien who would have no problem digesting us..? Is that worth the risk? The tasty, tasty risk?
  16. Jan 13, 2014 #15
    Well, to answer this, we have to look at the 6 class of nutrients: carbohydrates, fats, proteins, vitamins, minerals and water. Given that the fundamentals of biochemistry are universal, I would assume that any biology would use these same classes of nutrients; the question is whether or not we could use them.

    Right off the back, we know that there will be water as well as the minerals, so we should be fine there. However, the chances that a different biology would have evolved to use the same coenzymes (vitamins) are so small as to be non-existent from a statistical standpoint. So we know that we won't be able to sustain ourselves if stranded, so the question now becomes whether or not we could get calories.

    The first class of calorie providing nutrients (macronutrients) are carbohydrates and given that the hexoses are the ones that tend to polymerize best, any biology would have probably evolved to use them. First of all, hexoses are chiral earthly organisms all use the D forms, so if the biology used the L-forms, it would be useless to us (however, it may be that most biologies use both forms). Also, There are a total of 12 hexoses, 4 of which (glucose, mannose, glactose and fructose) we can metabolize, so the extraterrestrials would have to have both the correct chirality and compounds. Without a comprehensive understanding of the origin of life, it is impossible to make a probability call on this. There are essential carbohydrates (fiber) and given that these are any non digestible polysaccharides, we should be fine there.

    As for fats, the only thing that really distinguishes them from is the length of the carbon chain and degree of unsaturation, and we can metabolize virtually all fatty acids, so I would be willing to stake money (but not the integrity of any kind of manned mission to explore another world) that we could get calories from ET fats. There are two essential fatty acids (linoleic and alpha linoleic acids) that we need to consume and the odds that they would occur in an ET biology are small (but not so small that they should be ruled out completely).

    As for proteins, the amino acids that compromise them would, like the sugars have to have the right chirality (L in this case). On top of this, there are many amino acids apart from the ones that make up proteins here on Earth that an ET biology could utilize. However, there are some that claim that the 20 we use are the most optimal for biological functions. Of the 20 amino acids we can synthesize 9 and interconvert 2 of them, so if the 9 essential amino acids are present and they are of the right chirality, we should be able to sustain ourselves in terms of proteins, and again without a comprehensive understanding of the origin of life, we couldn't make a probability call here.

    So in conclusion, we could probably get some calories off ET food but we won't be able to sustain ourselves off it and the chances that we could get all of our essential macronutrients are small but not unrealistic.
  17. Jan 13, 2014 #16


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    At best, alien life forms would likely be partly to wholly indigestible. At worst ... well, use your imagination. If you got lost in a cave complex, got hungry, and stumbled upon an unmapped cavern teeming with unknown life forms, would you sample one, or boil and eat your leather belt first?
  18. Feb 11, 2014 #17
    I interpret "Could we eat an alien life form?" as questioning the survivability of a single meal - not whether we could sustain ourselves on an exclusive diet of alien meat or vegetables.

    There seems to be a consensus that the chirality could make parts of the meal non-nutritious, but it would not be poisonous.

    I think the real concern would be things like botulinum toxin, urushiol, or any of the scores of chemicals that earth plants and creatures use to make themselves inedible or unappetizing. I suspect that we would encounter a whole new natural alien toxin biotechnology that, as aliens ourselves, we would be wholly unprepared for.

    On the other hand, if we see fruit hanging from an alien tree, we might suspect that this is something that is (in a Darwinian sense) "intended" to be eaten - by the alien creatures. And that it is devoid of compounds toxic to those creatures. But if the light weight esters are too bland for them, what alternative compounds could be use to provide a more tempting selection of flavors - perhaps some of those slightly larger esters, organophosphates with more nerve pounding punch, soman, tabun, sarin, cyclosarin.
  19. Feb 11, 2014 #18
    Not true. Fucose is a L-carbohydrate that's critical for a huge swath of life and proper physiology .

  20. Apr 10, 2015 #19
    Not sure about your grammar but if I understood the gist of this right, the answer is "probably not" but also "we don't know". Look up "abiogenesis" along with "emergence".
  21. Apr 10, 2015 #20
    Hmmm... the molecules themselves, sure. But biology does not build up from molecular biochemistry neatly at all.
  22. Apr 10, 2015 #21
    Well unless we can run the formation of life over again another time, there's no way to answer this empirically short of actually discovering alien life.

    Now another question is: if we could not, in fact, eat 99.9% of the biospheres out there (it's possible that if there are enough biospheres that one may have developed with a similar enough set of biochemical basics that would be like the ones we have here, depending on how the possibility space is weighted, but I'd bet they'd be only a tiny fraction of the Universe's biospheres), it would seem there would be little reason for us to prefer colonizing a planet with extant biosphere to one with none in terms of interest for human settlement or living, right? (although of course an alien biosphere would be of IMMENSE scientific interest, but I'm thinking of with regards to planets as places to live, not as places to study.) In other words, colonizing Mars is probably just as good as colonizing Zweegax 9 with its weird alien biosphere (not to mention Mars is much much closer), if not better, in terms of being suitable for living on. (Of course Mars might have some life, so it might not qualify as "planet with no extant biosphere", but such life would probably be very scarce. We haven't closed the book on it yet. But even if it does, it's close enough to being a no-biosphere planet I'd mention it here anyways.)

    Although you could argue that one with extant biosphere might be suitable for terraforming, but it would be really evil to wipe out a whole biosphere just to replace it with our own. Better use a dead planet.
    Last edited: Apr 10, 2015
  23. Apr 10, 2015 #22


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    As has been said before, there are many plants and animals that are poisonous to humans on earth, so this question has no real merit, it's pointless speculation.
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