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If the Earth was edible, and was the sole source of food for its inhabitents, how long would it take for people to eat themselves off the planet?

Assuming a biblical creation story (a man and a woman), after how many years of humans dwelling on earth would the earth be eaten to the ground?

Assume the earth starts off looking the same as it does today, with the exception being that the land is edible food, and all ocean water is drinkable.

Assume that the volume of dirt one would require for a meal equals the volume of food normally consumed by humans in real life per meal.

Assume non-ration meals (3 full meals a day.)

Assume that the waste isn't edible and piles up.

Assume oxygen is provided through the soil.

Assume that the whole earth is edible (not just the crust.)

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    $\begingroup$ Where does the, uh, byproduct go? $\endgroup$ – workerjoe Oct 22 '18 at 15:12
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    $\begingroup$ With no evolutionary pressure, they'd die off within a few generations, due to sheer stupidity. Also, what happens to waste; where does the oxygen come from; and is the entire earth edible or just the crust? $\endgroup$ – nzaman Oct 22 '18 at 15:13
  • $\begingroup$ @nzaman edited to include details. $\endgroup$ – TheAsh Oct 22 '18 at 15:16
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    $\begingroup$ Earth will remain. Earth is a lump of matter held together by gravity. Even if you converted all the matter to human form, they'd still be just matter bound together by gravity. Earth would remain. $\endgroup$ – StephenG Oct 22 '18 at 15:19
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    $\begingroup$ This reminds me of Bethsalamin from THHGTTG - "Bethselamin is a fabulously beautiful planet whose primary industry is tourism. However, the inhabitants are so worried about the cumulative erosion by ten billion visiting tourists a year that any net imbalance between the amount you eat and the amount you excrete while on the planet is surgically removed from your body weight when you leave: so every time you go to the lavatory it is vitally important to get a receipt." $\endgroup$ – alexw Oct 22 '18 at 23:19
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2100 - 2500 years

Assuming

  • An individual consume 2000 grams of Earth each day
  • A growing population rate of 4 childrens per family
  • Lifespan of 100 years
  • Three generations per century
  • 5.97219 × 1027 grams of available Earth to consume
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  • $\begingroup$ As a bonus, after the first few layers, you no longer need to cook your meals. Just drop them on the ground! $\endgroup$ – corsiKa Oct 22 '18 at 21:25
  • $\begingroup$ Assuming four surviving (and reproducing) children per family is an extreme overestimate relative to anything seen in the real world. That's a population doubling every 33 years, which has never happened (or if it did, it was an extremely narrow window), even in humanity's most rapid growth periods (closest I can find is doubling from 3 to 6 billion from 1960 to 1999). For most of human history, you'd be looking at somewhere in the 2-3 kids per family range, with big steps back on population every time some new plague arose. $\endgroup$ – ShadowRanger Oct 23 '18 at 2:31
  • $\begingroup$ Importantly, this sort of estimate would have a single couple producing over one quintillion living descendants at the end of a 2000 year period. Last I checked, there were a lot more than one couple 2000 years ago, and there are a lot less than a quintillion folks on Earth today. $\endgroup$ – ShadowRanger Oct 23 '18 at 2:34
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    $\begingroup$ @ShadowRanger but 2000 years ago it was much harder to find food. The main challenge throughout history has been producing enough food for everyone. The moment you can eat anything, that issue disappears completely. $\endgroup$ – Tim Oct 23 '18 at 2:58
  • $\begingroup$ I'll grant you that (disease was another huge factor, though adequate food and water for all would reduce its toll). That said, there are other limiting factors. For one, rapid population growth almost always slows when child mortality drops (you get a generation or two of lag, then it stabilizes). The other issue is there are only about half a quadrillion square meters of surface area on the whole planet (before we start eating it). You'd need to fit 2000 people on every square meter of original surface area to fit a population of one quintillion. Those would be some elaborate food mines. $\endgroup$ – ShadowRanger Oct 23 '18 at 10:32
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The limit will be when poop is high enough that people cannot dig through it to get to food. They can dump poop into ocean or rivers, but that leads us to second limit:

They eat away dry land (till they can no longer dig from the bottom), so time to starvation depends on size of the continent you are on.

Technology could help dig deeper, or move to a different continent, but why would they develop technology if food is readily available?

If you do assume advanced technology, the sheer weight will make food below certain depth inedible. Here is a relevant link: https://what-if.xkcd.com/4/

PS I vote "earth be eaten to the ground" for quote of the day.

Edit: they can tunnel under the poop, going deeper and deeper until the poop collapses on them, or they get so deep that dirt is rock solid. Alternatively, they can launch poop into orbit (or off planet).

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  • $\begingroup$ And even assuming they can tunnel indefinitely, I imagine they would run out of ocean to drink well before they come close to eating the core. The ocean is only about 4km deep. $\endgroup$ – gmatht Oct 23 '18 at 4:16
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    $\begingroup$ You want to make "earth be eaten to the ground" the quote of the day? I'm kinda leaning towards, "they can tunnel under the poop, going deeper and deeper until the poop collapses on them, or they get so deep that dirt is rock solid. Alternatively, they can launch poop into orbit" $\endgroup$ – X-27 wants to Reinstate Monica Oct 23 '18 at 5:31

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