The 22 ingredients for a human

Posted on 17 Sep 2013


The human recipe includes a kilo of calcium, a pinch of salt

Though we do seem terribly complicated, it turns out that a human being can be built, completely intact and complete, with just 22 ingredients. From A to zinc, evolution has shaped just these two dozen or so elements to make up everything from Mozart to Manson.

According to the textbook Ecological Stoichiometry: The Biology of Elements from Molecules to the Biosphere, the formula for human composition ought to be based off the least common element of the bunch. The standby reference book presents the makeup of the human body in units of human cobalt; the body contains 375 million times as many atoms of hydrogen as of cobalt, for instance. There is only about a milligram of cobalt in the average human body, and as one Scientific American blog points out, that knowledge can lead us to the entirety of the human recipe.

35 kg Oxygen
6.4 kg Hydrogen
17.5 kg Carbon
1.5 kg Nitrogen
1.0 kg Calcium
0.54 kg Phosphorus
110 g Sulfur
72 g Sodium
120 g Potassium
76 g Chlorine
17 g Magnesium
18 g Silicon
2.5 g Iron
2.4 g Zinc
83 mg Copper
31 mg Iodine
12 mg Manganese
4.2 mg Fluorine
6.2 mg Chromium
5.4 mg Selenium
4.9 mg Molybdenum
1 mg Cobalt
These numbers were achieved with a process called stoichiometry. By using the famous Avagadro’s Number, which relates the atomic weight unit to grams, it’s possible to work out the amounts of every element in the list. There are almost three times as many hydrogen atoms as oxygen, for example, but since oxygen weighs roughly 16 times as much, it accounts for most of our weight, by far.

I recall an episode of Star Trek where the aliens referred to humans a “ugly bags of mostly water”.

Wait, Fluorine? I’ll make my human without that ingredient.

“… elemental fluorine, a highly reactive, poisonous, pale yellow gas. It is so reactive that it hardly ever appears in its elemental form in nature.”

Posted in: Biology