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Backstory (skip if desired)

Let's take our cute and self-conscious protagonist, Jayden! (For the people that read and responded to the post about the genetics behind keidran and the colonization of the Ilus system, they are in one and the same universe.)

He's your average starship engineer in all ways except he's a fox keidran. (Although not too long ago he wasn't fluffy.) This came with lots of problems, mostly trying to get used to being a keidran, and the rest being the fact that he can't get his hot chocolate. Completely devastating. How do you expect 'em to fix a derelict dyson swarm without his hot chocolate?

The Question

As we know, chocolate is toxic to dogs, and by extension, dog-people. The thing that makes chocolate toxic is a combination of caffeine, and theobromine. But before we handle that, let's start with an example keidran for testing.

enter image description here

(Image Credit to TwoKinds Author Tom Fischbach.)

Let's start with the familiar half of the equation. Caffeine. According to wikipedia, caffeine is a central nervous system stimulant. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance.

One side affect is that it behaves similarly to adrenaline by increasing heart rate, and thus exasperating cardiovascular issues, like heart attacks.

The other side of the equation, theobromine. It's the principal alkaloid found in cacao beans, and is named after the cacao plant's scientific name. It's toxic to all canids and for a rule of thumb, most domestic animals. Another rule of thumb is that the darker the chocolate, the more theobromine it contains.

The compound is actually toxic to humans, too, but we metabolize it much more efficiently, and so it has less time to accumulate.

You'd find around 60 milligrams of this stuff per 28 grams (1 Oz) of milk chocolate, and around three to four times as much in dark or bakers chocolate. For the average-weight human, it would take anywhere from 0.8 to 1.5 grams for toxicity to become a problem, which would be accompanied by sweating, trembling and a very bad headache. (And a higher risk of a heart attack.)

In accordance with veterinary guidelines, 1.3 grams of dark chocolate per kilogram of a dog's body weight is sufficient to be toxic. Assuming the average human weight of about 77 kilograms, and adjusting the BMI index to account for keidran being digigrade (walking on their toes) and thus being slightly taller, we can guess the average, healthy weight of a keidran to be in the ballpark of 80 or so kilograms. Which just so happens to be the approximate weight of our guy up top!

Knowing this, we can guess that it would take around 104 grams of bakers cacao to be toxic. Some simple math tells us that this is around 130 milligrams of theobromine. Being optimistic about some human traits of metabolism get carried over, we can make an educated guess that we need to have less than a fifth of this dose, or 26 milligrams or less, of theobromine per acceptable serving (how much a keidran could reasonably eat in one sitting) to be considered safe.

Knowing all of this, can we artificially create or genetically engineer cacao or a very accurate substitute to be safe for keidran consumption?

By artificially, I refer to extracting the theobromine from cacao without significantly changing its flavor, texture, etc and being economical to do. (Not needing to use billion-dollar molecular printers to manufacture it molecule by molecule.)

Would doing this be impossible? Will Jayden ever get his wish of hot chocolate as a reward for getting home? (Joke questions.)

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    $\begingroup$ Chocolate is also mildly toxic to humans. We are only moderately better then dogs at metabolizing it. In real life, the main difference is that humans are much bigger than dogs, so the same amount of chocolate results in very different doses per kilogram of body weight. Looking at the two characters in the picture, the furry seems to be about three times heavier than the girl, so that one cup of cocoa would have about the same effect on both. $\endgroup$
    – AlexP
    Jan 16 at 11:00
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    $\begingroup$ -1 for spending too much time writing a lengthy question and not enough time doing basic research. A 5-second Google search reveals that the chemical theobromine is the problem - and that depending on the chocolate type a canine the size of your creatures would need to eat up to 6lbs at one sitting to be toxic. In other words, as with all things in life, you're creature is safe so long as it eats chocolate in moderation. $\endgroup$
    – JBH
    Jan 16 at 16:31
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    $\begingroup$ Are you sure about the human stats? 1g would equal 450g of chocolate. I've definitely eaten multiples of that in a single sitting before and never had any kind of symptoms that you mention. Is it meant to say "0.8 to 1.5 grams per kilo"? $\endgroup$
    – Kaz
    Jan 16 at 22:24
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    $\begingroup$ "[Citation needed]" in Wikipedia may be a clue. is wrong. Elsewhere the LD50 level of theobromine for humans is given as 1 g per kg of body mass. psychologytoday.com/us/blog/the-red-light-district/202010/… However, the human body is complex, and a person might find that very low levels of a substance trigger migraines. Or they might not. $\endgroup$
    – David K
    Jan 17 at 3:59
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    $\begingroup$ Not to gloss over a whole lot of biology, but you said "chocolate is toxic to dogs, and by extension, dog-people", yet it seems it would've been equally valid to say "chocolate is safe for people, and by extension, dog-people". If they are dog-human hybrids, then you're basically trying to solve a problem you yourself created by taking chocolate tolerance from dogs instead of from humans. (If they are evolved dogs, that may be a different story.) $\endgroup$
    – NotThatGuy
    Jan 17 at 16:09

8 Answers 8

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chocolate is toxic to dogs, and by extension, dog-people

You've genetically engineered your furries using human technology which is clearly very sophisticated and capable. The tools are obviously there to modify caffeine and theobromine metabolism... why bother tampering with the chocolate, when you can just do a bit more engineering on the consumers of the chocolate?

As an alternative though, consider just... not doing anything? There's been various amounts of work done on theobromine poisoning, and whilst humans are somewhere between 50% to 300% more resistant to its toxic effects than dogs, they're far from immune. If a small child ate a bar of high-quality dark chocolate they'd be in a pretty bad way, too. Your dogpeeps though... they're approximately human size and mass in a way that regular dogs just... aren't. An 80kg dog could ingest nearly 1.3g of theobromine without ill effect. That's maybe 180g of dark chocolate, or nearly 600g of milk chocolate. The half-life of theobromine in dogs is >50% longer than in humans, so you might not be able to eat half a kilo of milk chocolate every day in perpetuity... but, y'know, just consume it in moderation. Humans have shown some ability to limit intake of dangerous but enjoyable substances below the lethal level, so it seems reasonable that your creations could too.

Will Jayden ever get his wish of hot chocolate as a reward for getting home?

The amount of theobromine in hot chocolate is likely to be even lower than in milk chocolate. He could have at least a pint of the stuff and not suffer from chocolate toxicity.

Note though that theobromine and caffeine aren't the only problems here... not all dogs have lactase persistence! Lactose tolerance is common in domesticated european dogs, but depending on where your engineers have been sourcing their genes, your chimeras could easily find themselves unable to digest lactose. So no hot chocolate.

(of course, you could engineer that out too, see first paragraph)

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    $\begingroup$ This is the correct answer. Dogs are moderately worse than humans at metabolizing chocolate, and they also have much smaller body mass. It is only the combination of those factors which makes it so that a dog can only eat a small fraction of the amount of chocolate an adult human can east. $\endgroup$
    – AlexP
    Jan 16 at 10:50
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    $\begingroup$ To add to this: We have white "chocolate" already, which has 0.0g of caffeine/theobromine anyway (beaue of a 0% cocoa content). We humans simply have no desire for a middle ground between milk- and white chocolate (to my knowledge) but in theory there is no reason to not have a 10% cocoa chocolate or so (milk chocolate is usually 35-55% cocoa). This "canine friendly" cocolat would contain even less theobromine and they'dhave to eat roughly 2.5kg of chocolate to come near danger. And at that point, they have other health problems $\endgroup$
    – Hobbamok
    Jan 16 at 15:16
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    $\begingroup$ Repeating what's above: "But from a writers perspective, its much more elegant to explain why the chocolate is not toxic than explain why keidran can metabolize it, and if I don't explain it, it looks like gross oversight from the writer, and if I explain the latter it could also be seen as a sloppy ret-conn to fix a previous scene." $\endgroup$ Jan 16 at 16:11
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    $\begingroup$ And its common sense that a keidran just shouldn't eat normal chocolate, so why try to defy the expectation and then try to justify it. $\endgroup$ Jan 16 at 16:12
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    $\begingroup$ @SamKitsune The only reason I can see why this is an issue at all "from a writer's perspective" is if you're concerned that a reader who has heard that chocolate is toxic to dogs will assume it is just as toxic to a keidran. If that's the concern, why not have a character express this concern, only to have someone else reply, "Don't be silly, it's no more toxic to a keidran than to you or me." No further explanation required. Much simpler than explaining how cacao beans were re-engineered. $\endgroup$
    – David K
    Jan 17 at 4:08
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Theobromine

I just read your first linked question, and it seems that you are proposing the creation of some kind of genetically modified "chimeric" creature. Basically a hominid-canid combination. Presumably the combination involves internal (organ system) changes as well as external modifications (cute furry tails and ears).

The problem canids have is that they can't process some common chemicals that human hominids can, such as theobromine and caffeine. Every pet owner knows not to give chocolate to dogs. They will suffer a wide variety of uncomfortable symptoms.

I'd argue that, since you are already positing an extremely robust suite of sciences and technologies to create Keidrans (or modify humans to become Keidrans), then you already have the means to make (or keep) them theobromine happy.

If it's not already known to your science, it would be a matter of discovering the relevant human gene and ensuring that the process included transferring that to the Keidran.

Reference: Jamie Rodriguez over on Quora mentions the following:

As to why this happens, we don't know; but some point to a variant in the cytochrome P450 enzyme gene called 1A2 (not the most creative name, let me tell you) that is more efficient at metabolizing methylxanthines (like caffeine or theobromine) than other variants found in other animals.

Just copy and paste the relevant genes from your human subject or delete the relevant genes from your canid modification library!

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    $\begingroup$ Yeah, I'd imagine that any would-be Keidran scientists would make certain that their new bodies would be able to properly metabolize theobromine, caffeine, and other commonly-encountered dietary or environmental chemicals (especially the recreational ones). $\endgroup$
    – Salda007
    Jan 16 at 6:43
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    $\begingroup$ @Salda007 --- Since these Keidran are apparently some kind of soldier, it might very well be that their mods preclude the ability to metabolise "recreational" substances. Or rather, they might be modified to pass such substances unchanged. $\endgroup$
    – elemtilas
    Jan 16 at 7:31
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    $\begingroup$ For a soldier, caffeine is an essential nutrient, just as it is for an IT worker. $\endgroup$
    – AlexP
    Jan 16 at 10:46
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    $\begingroup$ @SamKitsune It's not toxic because the inventors of the Keidran weren't so foolish as to make chocolate toxic to their creation. $\endgroup$
    – user253751
    Jan 16 at 13:53
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    $\begingroup$ @SamKitsune If you don't want it to look like a sloppy retcon, you could consider developing a formal world-building document(s) that you release as companion material that shows these were things you considered. That way, unnecessary details don't bog down the story, but people who care will still have access to them. $\endgroup$
    – anjama
    Jan 16 at 14:01
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Human Liver

enter image description here

People eat chocolate all the time and do not get poisoned. Their liver breaks down the theobromine:

In the liver, theobromine is metabolized into xanthine and subsequently into methyluric acid. Important enzymes include CYP1A2 and CYP2E1.The elimination half life of theobromine is between 6 to 8 hours.

Your dog people have people livers and not dog livers. They can digest chocolate no problemo.

Maybe the dogmans have hybrid people livers and dog livers. For breakfast they can eat chocolate without dying. For dinner they have langerloads of pork fat without cholesterol poisoning.

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Fox person does get toxic.

In the best way. Yes, sweating, trembling. Heart pounding. Nose so clear; smelling everything. A little drooly. Thoughts racing! So many ideas! That sweet sweet toxicity.

Keidran 1: I never knew chocoloate could be so... good!

Keidran 2: Because when you were human you always stopped before you got enough.

Keidran 1: I might be going to puke.

Keidran 2: OK you really have had enough.

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  • $\begingroup$ Umm... I am not sure how to interpret this... $\endgroup$ Jan 16 at 16:07
  • $\begingroup$ OOOOOOOOOOOOOHHHH!!! $\endgroup$ Jan 16 at 16:15
  • $\begingroup$ XDDD Fantastic answer. $\endgroup$ Jan 16 at 16:15
  • $\begingroup$ twokinds.gallery/download/art/1054/… $\endgroup$ Jan 16 at 17:47
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    $\begingroup$ Wait... I honestly didn't think of that... what if chocolate is a recreational drug in the same kind of way alcohol and coffee are to us humans... its like a social lubricant but... backwards... it makes you happy and go all kinds of funny. YESH. $\endgroup$ Jan 17 at 1:36
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In comments it's been exposed the real question is not "How do I make chocolate safe for dog-people?" but rather "How do I make the reader not feel that chocolate being safe for dog-people is a mistake?"

If you are worried readers will think this, you can pre-empt it by calling it out in-universe (similar to "lampshade hanging").

After the dog person eats chocolate, maybe a few pages later, a human character goes "oh my god! you ate chocolate! are you all right?"; the dog-person is totally confused; the human says chocolate is toxic to dogs and the dog-person says they have the human gene for digesting chocolate. Then you move on, and 0% of your readers are left wondering whether it's a mistake that dog-people can digest chocolate.

Alternatively you could bring it up before-hand. The human is passing out chocolate and hesitates before giving it to the dog-person. The human asks whether the dog-person can eat chocolate because dogs can't. The dog-person says they have the human gene for digesting chocolate. Again, nobody is left wondering.

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    $\begingroup$ Ah! I... Im a moron. I totally did the above in like the second chapter of the book. I wrote in that Jayden the fox-folk boi was busy working on reactor sims and sipping from a glass of hot chocolate, and then his friend Raine freaks and asks what the hell he was thinking, but then he explained why the chocolate was safe for dogs, not the other way around... Well darn... $\endgroup$ Jan 18 at 1:26
  • $\begingroup$ @SamKitsune To Jayden, drinking hot chocolate is normal and he has no reason to know Raine is freaking out because of the hot chocolate... unless this happens all the time. If you (a human) are eating chocolate and your friend freaks out, you don't assume it's the chocolate, right? Unless your friend says "chocolate is toxic to mammals!" $\endgroup$
    – user253751
    Jan 18 at 9:47
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We already make decaffeinated coffee and tea, alcohol free wine and beer, lactose free milk and so on.

So it is totally plausible that, with the right driver, chemists will find a way to make detheobrominated chocolate.

Usually this driver is under the form of an economic incentive (decaf and all I mentioned above sells, so there is a market to exploit), or a simple stumble of luck (if you ever heard how penicillin was discovered, you know what I mean).

This then begs the question why it has not yet happened...

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  • $\begingroup$ Noted, but the question hinges on wether or not theobromine is critical to making cacao look and taste like... well... cacao... $\endgroup$ Jan 16 at 5:26
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    $\begingroup$ @SamKitsune kako maybe. But not chocolate given how much of its vibe is reproduced in white chocolate with 0% cocoa or theobromine. $\endgroup$
    – Hobbamok
    Jan 16 at 15:18
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Synthetic chocolate

A society that is capable of building Dyson swarms and genetically engineering human/animal chimeras should also be sufficiently advanced enough in food science to create artificial chocolate flavoring. Which actually already exists in our world. I even found a patent for artificial chocolate flavor all the way back from 1954.

The reason why we encounter relatively little artificial chocolate flavor in most food products is that cocoa is still relatively cheap and (according to testimonies) most artificial chocolate flavors aren't all that authentic. But in a society where there is a large part of the population who can't eat chocolate due to dietary restrictions but crave it, there would be enough demand for artificial chocolate to invest resources into improving and mass-producing it.

Although Jayden might still loathe the fact that the synthetic chocolate he now has to consume doesn't taste quite like the original. Advertising might say that 9 out of 10 Keidran can't tell the difference. But knowing it's not the real deal might still bother him.

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I haven't yet seen mention of carob, which can have a flavor similar to that of chocolate but contains no caffeine or theobromine.

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  • $\begingroup$ It did get brought up in comments, and for me personally, taste terrible. I did consider it, and there are people who do like it, but that is nowhere near chocolate. $\endgroup$ Jan 19 at 14:49

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