Jokodo
Veteran Member
Related fact: There are a dozen or so chemical elements (plain elements, not specific organic compounds) that are presumably essential minerals, but we don't really know for sure because they are so ubiquitous in Earth's crust and the oceans and readily uptaken by plants and algae and passed along the food chain that there are literally no recorded cases of critical undersupply in all of medical history; we suspect that they might be essential nutrients because epidemiologically, certain conditions are rarer in regions with higher abundance or they are otherwise known to be benificial against particular diseases (flouride); or because experimental studies with other mammals have shown them to be essential there (and there's little reason to suspect humans can do without when rats can't); or by some other reasoning. There's a dozen or so candidates, including well-known poisons like arsenic and lead.
And that's just elements off the periodic table. There's only so many of them - I find a dozen potentially but not unambiguously essential elements out of that limited set quite astounding. Then, however, the same is arguably true for phytochemicals - among hundreds of thousands of them, alongside the well-known essential vitamins there may well be a whole bunch that are technically vitamins to, i.e. organic compounds the human body cannot produce but needs for its functioning, just that they are so ubiquitous that we never noticed. Many of them may well be poisons.
This arguably an underrated obstacle to interplanetary, let alone interstellar travel. The logistics of bringing along supplies of dozens or hundreds of poisons and spiking our food with just enough to roughly match the ambient supply on Earth without ever reaching dangerous levels, just in case some of them turn out to be essential nutrients unbeknownst to contemporary medicine, are not something to scoff at.
Of course, our knowledge about our bodies' nutritional needs might be much better by the end of the century (it's a bit like cold fusion, right: we'll have cracked it in 10 years; been having cracked it in ten years for the better part of a century). But that doesn't entirely remove this obstacle at least for the purposes of colonisation. Bringing along enough arsenic to supply a crew of hundreds in fully recycled closed system is hardly an issue. Bringing along enough arsenic to last a growing colony of millions of people, with inevitable leaks into the environment, for 1000s of generations is quite another story. And, not knowing what we will encounter, we'd have to do this for a whole bunch of minerals (some of them with recommended daily allowances several orders higher than arsenic if indeed arsenic turns out to be an essential nutrient) - just in case they cannot be mined in sufficient quantities whereever we end up.
Here's a relevant discussion about micronutrients and their toxicity: A toxic brew we cannot live without with some further points I didn't elaborate on:
- the margin between required and dangerous doses can be quite low - on the order of a factor of 5 in some cases. Thus a planet with a third the selenium and three times the arsenic would require us to preprocess all soils used for growing plants and supplement selenium, and quite possibly the reverse is also true for a planet with lower arsenic and higher selenium.
- plants, even as they may not require some of the nutrients animals need, can hyperaccumulate them to levels that are unsafe for most animals. In other words, and only slightly exaggerating: The only reason most plants aren't toxic is that there aren't enough toxic elements in the ground for them in most places. I
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Read the previous paragraph. ASI (Artificial Super-Intelligence) can reproduce with mining operations and robotized factories. The infrastructure for needed ASI "ecology" is hugely simpler than establishing a "living planet."
