JRiseley said:
I'm sorry, this is just making you look desperate (in the sense that you won't admit it's a rubbish hypothetical). Just because you allude to some obscure deus ex machina concepts doesn't mean that it's hard science. We eat proteins, carbohydrates and lipids. Amino acids are in proteins. We can suffer deficiency illnesses if we lack protein in our diet (such as Kwashiorkor), but we cannot die in the way you seem to think.
These amino acids are all essential in that they cannot be created de novo (out of nothing, in the body). They have to be supplied by the diet.
1 - You won't die from lacking them, and 2 - how did the aliens create essential amino acids, de novo?
Eventually, yes, you would suffer various diseases from a lack of them. A loss of three essential amino acids would prove deadly. For example, Tyrosine is normally unessential, but in people with phenylketonuria, a lack of Tyrosine would lead to severe neuro problems. Not exactly something you can deal with on a hostile planet.
The second question you ask answers itself; what is essential for human beings is not essential for other organisms, who can still synthesize the substance. Where do you think Vitamin K comes from? We humans cannot synthesize it and rely on the normal flora of our guts to do it for us. This is why long-term antibiotic treatment often results in various bleeding disease and increased prethombrin time. Every essential amino acid undergoes synthesis by some organism for which it is not essential. This is why, for example, the ability to synthesize Histidine might be used for an Ames test. A bacteria may be able to synthesize the essential FOR US amino acid Histidine. Introduce a recombinant with a single point mutation to make the organism unable to synthesize Histidine, then expose it to a substance to see if it reverts faster than the background rate of mutation. Bingo, an organism for which Histidine was not essential, then was, then wasn't. (Yes, I am aware that the Ames test is overly sensitive; the point stands.) At this point, I'm forced to conclude you are not aware of what an essential amino acid is. It's a relative term; we say it's essential when we mean essential
FOR US. Other organisms will undergo de novo synthesis of what we cannot, and vice versa. I really don't give a rat's left testicle what's essential for a rat; they seem to be doing just fine. This can be expanded to any essential nutrient, such as the vitamin C example below.
We cannot synthesize somewhere between 8-10 AA's (again, depending on the book and how you define "essential." We -do- synthesize a small amount of methionine via the homocysteine salvage path, but it cannot and does not come close to what we need for de novo protein synthesis. So without it, you are screwed. Is methionine essential? Depends on the text.} A similar pattern exists with the synthesis of ascorbic acid. Humans and other primates need it or they get scurvy and die. Most other animals still retain a synthesis pathway for it. For humans, vitamin C is essential; for rabbits, it's something they produce in small quantities as necessary.
Since you do lose amino acids from your body to actions like oxidation attack by reactive oxygen species, incomplete reuptake in the kidneys, loss through injury, secretion in the form of surface proteins, secretion of Ig's, creation of keratinized skin, etc ad nauseum, you would eventually "run out" of your store of said amino acids. Tryptophan is lost making neurotransmitters like melatonin and serotonin and is also essential. Suppose that is a missing AA in your diet. You are royally screwed; enjoy neuropathy and death.
Also, you'd do yourself more credit by refraining from personal attacks. And you may want to hold off on saying something is -rubbish-.
Finally, the point of a hypothetical "philosopher's puzzle box" is to explore a moral question; the premises are taken as a given rather than nitpicked. Nor was it my hypothetical example to begin with. Hell, one of my favorite attacks on utilitarianism in moral philosophy involves using a really fat guy to stop a train and save lives by shoving him on the tracks. How on earth someone got big enough to stop a train isn't the question. The real question is, "Is it alright to actively use a person, taking steps which will definitely kill them, to save the lives of others?" It's often also asked in the form of a physician who can murder one patient, harvest their organs, and save four others who will die without those organs. The Kantian says people cannot be used as means to an end, the utilitarian says the expected utility is greater by killing one to save four, and we're off to the very, very boring freshman in philosophy 101 races.
Oh, and...I wasn't the OP. It wasn't MY hypothetical question.
