Why Humans Don't Spontaneously Combust
The best athletes are often called "explosive." That's an apt description. In the ten seconds that elite sprinters dash 100 meters, they produce about 25,000 joules of energy, about the same released in the near-instant detonation of six grams of TNT, which would blast a hole in a metal plate. Olympic weightlighters output even more power. In the mere second it takes a 250-pound lifter to jerk a loaded barbell, they produce roughly 5,000 joules of energy.
But unlike TNT, humans are not literally explosive. Even at our most energetic, our power is contained. Though myths abound, humans do not actually spontaneously combust.
We take the fact that we don't conflagrate for granted, but as biologist Siddhartha Mukherjee wrote in his acclaimed 2016 book, The Gene: An Intimate History, it's a rather remarkable thing.
"Life may be chemistry, but it's a special circumstance of chemistry. Organisms exist not because of reactions that are possible, but because of reactions that are barely possible. Too much reactivity and we would spontaneously combust. Too little, and we would turn cold and die."
We are not hunks of rocks, boring but enduring. Nor are we supernovae, bright but brief. We inhabit a special in-between space: life.
We can thank proteins for our Goldilocks level of reactivity, Mukherjee says. These tiny molecular machines are the workhorses of life, and one of their many tasks in the human body is to regulate chemical reactions.
"Proteins coax and control these fundamental chemical reactions in the cell – speeding some and slowing others, pacing the reactions just enough to be compatible with living."
This, Mukherjee wrote, allows us to "live on the edges of chemical entropy – skating perilously, but never falling in."
