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It basically says it all in the title. I assume the human will eventually succumb to malnutrition, but I wonder what the minimum number of trees are necessary to provide the human with enough energy to survive the longest.

Assuming the human:

  1. has ample shelter
  2. has a way to open coconuts
  3. is in a climate that can support year-round coconut production
  4. is on an island big enough to contain the minimum number of trees
  5. has no other form of food on the island / surrounding waters

Bonus : How long until they succumb to malnutrition and die?

n_b
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  • Just make sure you never eat a coconut that's under- or over-ripe... In either of those states, they can be a fairly powerful purgative, and... well, let's just say that on a deserted island, the effects would likely lead to severe dehydration, which would either kill you, or render you unable to keep up the coconut-harvesting efforts for long enough that the malnutrition would finish you off. – anaximander Sep 07 '16 at 10:40
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    @n_b are you assuming there is a freshwater source or does the single human need to get his water requirements from coconut water – Foon Sep 07 '16 at 19:12
  • @Foon Yeah, there is fresh water. But you could assume there isn't if it's more interesting that way. – n_b Sep 07 '16 at 22:56
  • https://www.youtube.com/watch?v=F8TJsbpt-C4 – Phonics The Hedgehog Sep 08 '16 at 03:23
  • Imagine how funny it is seeing a man in full coconut based weoponry. XD – CadmusMorale Sep 08 '16 at 03:26
  • Relevant real-life example: https://en.wikipedia.org/wiki/August_Engelhardt a fictionalized satire/pastiche of his life has been novelised as Imperium by Christian Kracht. – Ruben Sep 08 '16 at 07:14
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    Can they drink sea water for sodium ? – Babika Babaka Sep 08 '16 at 08:29
  • @SpaceLizard Drinking sea water would kill the person long before starvation became a problem (or did I miss the joke?). – chepner Sep 08 '16 at 13:11
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    @chepner I wanted to ask if they could drink sea water for sodium, as a complement of their coconut diet, not as a replacement for drinkable water. (Sorry, I'm not fluent in English, is there a better way to ask it ?) – Babika Babaka Sep 08 '16 at 13:15
  • keep in mind that coconut trees are actually quite dangerous. The more trees you have on the island the higher risk your person has of being killed by falling coconuts. – YoungJohn Sep 08 '16 at 14:08
  • @SpaceLizard - that might be a good idea, not just for salts but also because there are minerals are in seawater. As they have a source of sweet water the person should be able to counterbalance the dehydrating effect... as long as they keep the seawater consumption to small medicinal levels and keep hydrated with coconut water. They still will lack nutrients, but it should help. – Megha Sep 08 '16 at 19:55
  • Other vitamins coconuts lack, vitamin A, D, B-12, and calcium. Additionally he has to eat roughly 375 coconuts a day to get enough vitamin K. http://nutritiondata.self.com/facts/nut-and-seed-products/3106/2 – John Jan 17 '17 at 14:53
  • @John Interesting, but providing they don't sustain any injury, they might not need to worry too much about vitamin K? I wonder if other parts of the cocoanut tree could provide missing nutrients. – n_b Jan 17 '17 at 18:39

4 Answers4

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Well, start with the Wikipedia page.

On fertile soil, a tall coconut palm tree can yield up to 75 fruits per year, but more often yields less than 30, mainly due to poor cultural practices

The same page lists the nutritional value as 354 kcalories per 100 gram serving.

And finding the weight of the edible fruit part alone, the USDA says that one medium coconut has 397 grams of meat.

So one tree gives 354 × 3.97 × 30 ≈ 42,000 kcal/year.

Of all the nutrients needed, I expect lack of calories will kill someone the fastest. You can repeat the analysis with other requirements and timescales for the deficiency to become debilitating, with the information “food label” on that page.

If each adult male needs 1,500 kcal per day, that comes to 13 trees. But that’s for a sedentary white-collar worker; it’s suggested that harvesting will take some effort and the castaway may need to be more active in general. With a ration of 2,000 kcal per day, 18 trees will be enough. That assumes production is continuous or food can be stored, and that the wild coconut is similar to a “medium” cultivated coconut. Add a few extra to be sure. You can adjust that based on the activity level you need for the story.

We assume the low value indicated for yield at least for the first year. If he knows what he’s doing and “farms” them then yield can go up. But if there is nothing else to eat there’s nothing to use as fertilizer either, so it might be slim pickings.

Community
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JDługosz
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    Why the downvote? It’s an exact answer to the question! Please leave a comment to explain how it is «egregiously sloppy, no-effort-expended post, or an answer that is clearly and perhaps dangerously incorrect.» so I may improve it. Because I just don’t see any of that applying here. – JDługosz Sep 06 '16 at 18:23
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    Does a coconut even provide the nutrients to sustain life? I have no idea. I would've guessed there'd be some serious problems like rickets or some other missing critical piece to make surviving on just coconuts a short-lived option, regardless of the coconut count. Anyone know enough nutrition info to answer? – SRM Sep 06 '16 at 18:47
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    @SRM Coconuts almost certainly don't provide all required nutrients, but that's not a problem that can be solved by growing more coconuts, which seems to be the only option granted in the OP – Deolater Sep 06 '16 at 18:56
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    Agreed - you will not get all essential vitamins from a coconut. There is no B12, for example, in a coconut. You will not survive without b12 from some other source, or if you do, you will be suffering some major hallucinations - like talking volley balls... – Jim Sep 06 '16 at 20:56
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    It should be noted that coconuts are not the only edible part of a coconut palm tree. – rek Sep 06 '16 at 21:02
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    Are other edible parts renewable? – JDługosz Sep 06 '16 at 21:05
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    I'm accepting this answer as it tells me I need 81 coconut trees for someone to fulfill their calorie intake. I should have made it more clear in the question that I was also wondering how long they could survive until malnutrition takes them, so I've added it as a bonus. – n_b Sep 06 '16 at 21:05
  • @JDługosz No, but if you're planting more trees it won't matter. Coconut palms take 4-10 years to mature, so if he can't last that long long on coconuts alone this would at least provide some variety. – rek Sep 07 '16 at 03:57
  • So you mean eating sprouts and roots of new plants? – JDługosz Sep 07 '16 at 06:27
  • @Jim B12 is a poor example because can be stored and reused by your body for an extended period of time (eg it takes many years for a supplement free vegan diet to cause problems from B12 deficiency). Numerous other vitamin/mineral deficiencies would cause crises sooner. – Dan Is Fiddling By Firelight Sep 07 '16 at 14:52
  • the kCal required are much more because if he have the strictly required number of palms he have to climb to get coconuts. I would add extra 50% palms. – CoffeDeveloper Sep 07 '16 at 14:53
  • Actually, hyponatremia will likely do you in well before you can starve to death, so the minimum number of trees may well be smaller than18, of course, you can always drink a little seawater to fix that, but still... – WhatRoughBeast Jan 16 '17 at 18:51
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In addition to JDługosz's answer on the number of trees required to provide calories, I would suggest growing further trees to ferment into coconut milk kefir and alcoholic beverages. Although best made with starter cultures, there are wild yeast almost everywhere on earth that can start fermentation. Because these cultures contain yeast and bacteria they contain nutrients not found in the original coconut. The yeast (trub) can be collected after fermentation and processed into yeast extract for a nutritious and tasty supplement. In particular, yeast is rich in B vitamins that are otherwise hard to obtain.

And booze helps pass the long years of subsisting on your own on an island...

Jack Aidley
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BONUS QUESTION: This page http://www.npr.org/sections/thesalt/2015/12/03/457124796/death-by-coconut-a-story-of-food-obsession-gone-too-far says a man lived on coconuts from 1902 (and Wiki says he adopted a monodiet around 1905 or 1906) until imprisonment during WWI in Sept 1914, at which time he weighed 86 pounds. So, a while.

Xplodotron
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    The article says "from 1902 to 1919." 17 years?!!? That's quite a lot. Things are looking up for the protagonist. – n_b Sep 06 '16 at 21:44
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    No, read again. He wasn't there the whole period, there were hospitalisations and return to Germany. Other people joining the colony died within months. – congusbongus Sep 07 '16 at 06:22
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    If you can edit the answer to when he left germany to when he returned that would give you a good idea of the answer... otherwise this answer is wrong with it implying that he lasted as 17 years. – Durakken Sep 07 '16 at 11:07
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    Sorry guys, I did edit with a bit more detail. Best I can tell, he was on the island from 1902 but was also eating other fruit until true monodiet in 1905 or 1906. Other people on the colony did die, though I can't tell if that was from malaria or monodiet. I bet this guy did not stick to his monodiet because he seems like a real piece of sh*t nutjob. – Xplodotron Sep 07 '16 at 16:28
  • " At the end of his life, der Kokovore was reduced to a mentally ill, rheumatic, severely malnourished sack of bones with ulcers on his legs. He was only 44" – Deolater Sep 08 '16 at 15:46
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It seems body stores quite a lot of B12, thus can survive very long without it. The guy could obviously drink sea water, but, if he does not, he will soon die of sodium deficiency. It seems humans should take at least 500mg of sodium per day [1]. I experienced sodium deficiency first hand, its no fun.

Cem Kalyoncu
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