Giant food ball

Sunday 10 June 2007

We had meatballs for dinner last night, and as Max was eating his, he got thoughtful, and asked:

If you took all the food that all humans have ever eaten, and mashed it into one giant ball, would it be as big as the Earth?

Good question. It called for a quick series of incredibly inaccurate back of the envelope calculations:

  • We estimated that one person’s daily food would be a ball about 10cm in diameter, or about 524 cm3.
  • Times 365 days/year, one person’s yearly food ball would be 191250 cm3.
  • Times 6.5 billion people on Earth, today’s humans consume 1.25×109 m3 of food each year.
  • Now comes the tricky part, estimating over the whole course of human history. Humans have been around for let’s say 200,000 years, but the growth has been exponential over that time, making it hard to flatten it out for simple calculations. (Probably some of my forgotten calculus would help here, but did I mention it’s forgotten?) A good estimate is that there have been 100 billion humans ever.
  • If we take a yearly intake of 191250 cm3, times an aggregate average lifespan of 50 years, times 100 billion people, we get a total all-time human consumption of 9.5×1011 m3.
  • The Earth has a radius of 6372 km, giving it a volume of 1.1×1012 km3 or 1.1×1021 m3.

So, rounding a little further, humans have eaten 1012 cubic meters of food, and the Earth is 1021 cubic meters in volume, so we’re only off by a factor of a billion!


I once ate 10^11 cubic meters of pasta. I won't make that mistake again...
Haha, next thing he will ask how much poop humans have produced. Will you blog about that too? :-D
I thought he was going to ask, "What are meatballs made of?" And you'd say, "Um... well, technically, dead, ground up cows."
Cool. Actually, it'd make a great interview question! It screams of the Microsoft-y questions that are detailed in How Would You Move Mount Fuji.
Humans are much older than 200000 years. Even Lucy was 3.75 million years old, and she was for sure not the first human.
(smacks lips, drools) Mmm ... Food Balls ...
Actually, that is a good interview question..... similar to the "how would you calculate how much does a 747 weight..."

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