Would alien life be more likely nutritious, toxic, or inedible by life on Earth?

The question is: Would alien life be more likely nutritious, toxic, or inedible by life on Earth?


Why, on earth, would you eat aliens? Apparently the questioning person is mad from starving.

At first thought, I would not start eating a newly discovered foreign species that would make the top latest sensation to mankind!


Under the assumption that alien life is based on DNA but coding is completely different and some amino acids are different you can go further and assume the environment leading to such a composition contains water in liquid form. So if the pressure is one atmosphere the temperature for living should be above freezing and below boiling. Otherwise DNA would not work. Active living would require a temperature above freezing, inactivity would allow lower temperatures. So, from the assumptions given we can assume an environment somehow familiar to us. From the assumptions we cannot deduct, however, the kind of atmosphere nor the surface nor the pressures on the planet leading to that alien life.

As you may find on earth conditions without oxygen or full of water or dry surfaces, and all those places still bearing life, some of earthen life could live on that alien planet too and endanger the alien life, so be afraid of contaminating that place.

Now looking on DNA, that the alien life contains to harbour its genetic information, there are different possibilities for it even when chemically quite the same: it can be left-handed or right-handed, for example. I would guess chances are 50 %, but I do not know sincerely. If the alien DNA is optically different from ours, then sugars are different to ours and of no nutritional value to earthen life, expect for some fungi. If sugars rotate the other way chances are quite well amino acids rotate the wrong way too. That renders them unedible for us (except for some fungi) and peptides composed of the wrong winding amino acids might be toxic to us as fungal toxins that are composed of "wrong" winding amino acids.

But, since all life on earth derived from ONE origin only and all life on earth are the relatives of the first one, we have only ONE sample to look at how life can be expressed. So, there is NO likeliness to assume on alien life biochemistry.

So I come up with some statements (Under the assumption that alien life is based on DNA but coding is completely different and some amino acids are different):

  1. If alien life contains fatty acids (what I would assume under the assumption of DNA and amino acids) some of these fatty acids are edible to us and some will be toxic to us.
  2. If alien organisms contain molecules composed of subunits of the same rotational orientation as our life is composed, it may be edible to us.
  3. If its proteins are composed of amino acids of the "wrong" rotational orientation they will be unedible to most life on earth and are to be considered potetially highly toxic, as mushroom poisons.
  4. If its sugars are rotating in the "wrong" way these are unedible to us.
  5. There are (fungal) microbes on earth that can endanger that alien organisms.
  6. Any alien material inoculated may provoke immune reactions.
  7. Be prepared that metabolites of alien organisms may be toxic or highly toxic to us, as some microbial metabolites.


I would advise you not to chew the aliens before having performed long-term animal studies. Long-term means for at least three generations of these lab animals.


For information on optical rotation see: Rolf Kohl's answer to Why are L-isomers more prevalent in biological systems than their R stereo chemical counterpart?

OK guys, this is into my science-fiction-mode. I enjoy writing stuff like this, but it shouldn't represent reality. Dicitur dicum.

There are a few schools of thought about this:

  1. (Panspermia) In this theory, the probability of life having arisen is infinitesimal in a single galaxy, but it did happen. The mechanism of DNA has been found once in our galaxy (never mind other galaxies; they are far too distant), and spread to Earth and potentially other systems therein.
  2. They would be toxic. Because, the organic molecules in their bodies (and, they would most likely be organic molecules, because of the affordabilities given by carbon chemistry) would be completely incompatible with ours.

In this case, there may be a common proto-ancestor to DNA, but it is probably so far back in time, and distantly-evolved, that we would not be able to eat any form of food from it, just because it is so different from our biology.

So, go book that ticket to Proxima Centauri, but bring along those MRE rations when you do go.

Hm, this is like comparing apples to oranges. If an alien life form is based on carbon as our Earth life forms, then we must say it CAN be nutritious, or toxic. Definitely all biological life forms on Earth are edible. The consequence is that some are toxic like certain plants, mushrooms, fish, etc., nevertheless they are edible if you intend to commit suicide, or enjoy a good session of diarrhea and vomiting. Even tree bark is edible.

So if it is carbon based it can be all the three above, but if it is based on other material, then it CAN be edible, but most likely be toxic and not nutritional.

Good question :)

If such life evolved along the same biological path as life on Earth in choosing the same protein "handedness"(right versus left), some of it should be as edible and digestible as the life on Earth. Even delicious.

However, depending on the chemical evolution and conditions on the planet life evolves on, much of it could also be poisonous. However, if our Simian relative can digest it without any adverse affects, humans too should be able to do the same. There is also the possibility that we could self-evolve a branch of humans to eat and tolerate such food.

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