Dextro won’t kill you, honey. Still, proceed with caution.

I’ve been reading a variety of materials on amino acids lately and my good friend who has a phd in microbiology has also informed me of some fascinating facts.  Mass Effect is not a perfect example of real science, but I really wish it was because they did so much right.  Sometimes, however, they do fudge up.  I mean, breath masks in space?  And it’s because you like them not because they’re practical and a viable option?

Kill me now.

But one fallacy in the Mass Effect universe is the prevalent assertion that Turians/Quarians cannot ingest human food and vice versa.  It is stated many times in all three games that it’s not possible for Turians/Quarians to obtain nutrition from Levo proteins and that it is even potentially fatal, causing an allergic reaction.  This would not only include food but other things such as saliva and semen, which would make sexual relations between the species a bit difficult.  The sexual issues seem to have become null and void as of ME3 (which is strange given the writers’ continued stance on Levo food being unfit for Dextros), but this whole “Dextro can potentially kill me" thing is far from the truth.

This assertion basically states that if Shepard sucks Wrex’s dick she’s going to be fine and dandy because they’re both made of predominantly Levo-amino acids but if she sucks Garrus’ dick she’s going to “die” or at least get a severe allergic reaction.  There was a time in the Mass Effect fandom that people actually believed Garrus and Shepard could not kiss (thankfully proven very wrong in Mass Effect 3), despite the fact that Tali and Shepard kissed quite successfully in ME2.  I’m of the belief that Mordin’s “advice” was the real kickstarter in this belief, and I’m very happy to see it debunked in ME3.

Despite this debunking of the kissing myth, there is still the mention of dextro vs. levo food as well as crossbreeding between the species, which I’ll get to a bit later.  On the food issue, Tali states to Garrus at one point in ME3, “But [Liara] can eat [human] food.”  She makes a strong differentiation between her and Garrus and the rest of the Normandy crew over their supposed food consumption.  Matriarch Aethyta also indicates the ill effects of one species ingesting another through her little story of a Krogan drinking “liquid Turian” and no one coming out of that “looking pretty.”  There has also been wide fan speculation over whether or not Tali and Garrus starve at the end of ME3.

But D-amino acids are not toxic. Levo (left-handed) and Dextro (right-handed) indicate the direction of the rotation of the spiral that is the chemical structure of the molecule.  Proteins contain only one chiral form of amino acids which is either one or the other.  All amino acids on Earth are left-handed, disregarding some bacteria.  However, sugars are oriented as right-handed.  Has anyone else had Mint?  Mint has a D-amino protein that gives it flavor.  The Mass Effect universe would tell you ingesting Mint would likely kill you or give you an allergic reaction (well maybe if you’re allergic to it) because it has a D-amino acid in it.

Shit keep this stuff away from me before I die of anaphylactic shock!

Also, there are the Dextro-amino acids found in mycotoxins such as Penicillin with d-Alanine.  Oops.  I guess you can’t take that if you’re in Mass Effect even though it kills the bad bacteria and helps you!

There was a study composed a while back concerning human ingestion of Dextro and they postulated that it would pass freely through our system without us receiving any nutrients, which is stated as a possibility in the Mass Effect universe.  However, evidence also suggests that we would in fact break them down and convert them into usable Levo, which I would take to be similar for those Dextro based lifeforms with regards to Levo proteins.  The study states: “There is no evidence for the toxicity of D-amino acids in humans. D-Amino acid oxidases have been demonstrated to be active in humans, but other factors could influence the metabolism of D-amino acids, such as rates of transport, action of intestinal enzymes and bacteria, absorption and renal clearance. However, no toxic effects have been observed following intravenous administration of chemically pure racemic amino acids to adults and infants in larger concentrations than expected to be consumed from normal food intakes." (Trends in Food Science and Technology, Page 96).  Now, keep in mind that we know next to nothing of how proteins work on other planets.  They could very well have some sort of toxicity for humans.  After all, thousands of years of evolution on one planet have likely not made us well-equipped to handle ingestion of plant-life on other worlds.

However, NASA scientist Dr. Jason Dworkin recently discovered that meteorites contain much higher levels of L-amino acids than D-amino acids.  He also found that meteroties with more water had greater amounts of L-amino acids and that this may indicate that “the creation of extra left-handed amino acids had something to do with alteration by water.”  He further theorized that matter from space containing these L-amino acids could have come to the early Earth and triggered the evolution of left-handed proteins, thus the reason for humans being Levo instead of Dextro.  He stated that “you can’t mix [D-amino acids and L-amino acids because] if you do, life turns to something resembling scrambled eggs — it’s a mess.”  Therefore, no hybrid babies for humans and turians (sorry or you’re welcome)!

Furthermore, if we find that life is “based on right-handed amino acids, then we know for sure it isn’t from Earth. However, if the bias toward left-handed amino acids began in space, it likely extends across the solar system, so any life we may find on Mars, for example, will also be left-handed. On the other hand, if there is a mechanism to choose handedness before life emerges, it is one less problem prebiotic chemistry has to solve before making life.”  Therefore, it is interesting that Bioware chose to have more alien species evolve on the left-handed spectrum than the right, and this line of reasoning is potentially correct given the possible bias toward Levo that we can garner from the human example.

A recent article about the research of chemistry professor, Dr. Ronald Breslow, includes discussion on d-amino and l-amino acids and their role in creating life in the universe.  He questions why amino acids, including sugars, exist solely in one orientation or shape, and raises the possibility that life could evolve (using dinosaurs…) on another planet of the d-amino variety with l-amino sugars; a perfect mirror image to Earth.  This is indeed true to the Mass Effect universe given that both Turians and Quarians evolved from right-handed amino acids (nice idea Bioware).

Dr. Brewslow further discuses why amino acids are left-sided instead of right-sided on Earth.  He postulates the idea that “the unusual amino acids could have been carried to a lifeless Earth by meteorites about 4 billion years ago” and that this concept could potentially explain the L-geomtry and D-sugars in DNA.  In a quote from the article he states, “An implication from this work is that elsewhere in the universe there could be life forms based on D-amino acids and L-sugars.”  So with this line of reasoning we could assert that Turians and Quarians, while being D-amino based also have L-sugars, the exact opposite of what we have on Earth.  And if humans can safely ingest D-sugar then Turians/Quarians can safely ingest L-sugar because it’s prevalent in their evolutionary make-up.

Here’s an interesting quote from another article about d-amino acids in humans:  “Recent evidence has shown that d-amino acids are present in animals and humans in high concentrations and fulfill specific biological functions. In the central nervous system [of humans], two d-amino acids, d-serine and d-aspartate, occur in considerable concentrations. d-Serine is synthesized and metabolized endogenously and the same might account for d-aspartate. d-Serine has been studied most extensively and was shown to play a role in excitatory amino acid metabolism, being a co-agonist of the N-methyl-d-aspartate (NMDA) receptor. Insight into d-serine metabolism is relevant for physiological NMDA receptor (NMDAr) activation and for all the disorders associated with an altered function of the NMDAr, such as schizophrenia, ischemia, epilepsy, and neurodegenerative disorders. d-Aspartate appears to play a role in development and endocrine function.” (Molecular Genetics and Metabolism, Volume 85, Issue 3, July 2005, Pages 168–180).  This evidence makes me strongly question the persistent belief in the Mass Effect universe that humans can’t eat Dextro food and Turians/Quarians can’t safely ingest Levo food, at least in most cases.

The whole point I’m trying to make is that just because, for example, Turians and Quarians are Dextro-amino does not mean they are 100% biologically compatible and can interbreed.  That is like saying a chimp is compatible with a human because they’re composed of Levo-amino acids.  With all those human-chimp hybrids running around I can see the confusion…oh wait :3

Quarians are not similar to Turians just because they are D-amino based.  They evolved on completely different planets in completely different environments.  Quarians and Turians are about as similar to each other as a Krogan is to a Human.  Just because they are the only Dextro-amino species does not mean they are related or can breed.  Seriously, when someone says they (or any other species in the ME universe) can crossbreed I just:

I am under the impression that all species in the Mass Effect universe are able to engage in sexual relationships with one another regardless of supposed dextro/levo incompatibility as well as potentially eat opposite chirality food.  Besides, I would think that having intercourse WITH A DIFFERENT SPECIES would require caution no matter the amino acid involved.  Yes, Tali and Garrus can have sex and Wrex and Shepard can fuck like crazy, but them having similar amino acids has little to do with their sexual compatibility and would not be a factor in whether or not they can eat the same food.  I would be more worried about that fact that all these species did not evolve on the same planet than whether or not they’re amino acid compatible.

Until we someday meet a species that is of the d-amino variety we cannot properly postulate how our sexual biologies will react to foreign DNA or what it will mean for our food consumption.  Given the current research, however, and what we know of amino acids’ role in life on Earth, we can assert that it is possible for Levo’s to ingest Dextro food and so on without any major ill effects, and that we can even receive nutrition from opposite chirality proteins because biology is seriously that amazing and adaptable.  Our Dextro friends would not starve to death on a Levo-based planet, and french-kissing a Turian is not likely to kill you, although you might want to watch our for those teeth…

In conclusion:  Shepard, Tali, Liara, Ashley, Miranda, Jack, Kasumi, and Wrex can go down on Garrus, and vice versa.  It’s a beautiful thing <3

I hope this was an informative read for everyone and that I didn’t jump around TOO much haha.  I tried to keep it as scientific as possible (please correct me if anything is misinformed), but it’s difficult finding research on D and L compatibility.

Here’s some Dextro Energy for all you humans.

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