"We are stardust..."

This is one of my all-time favorite Fun Facts:


Harlow Shapely's quote has entered the larger culture - that "We are stardust, we are golden" as Joni Mitchell / CSN paraphrased it -- that every single heavy atom in us had to have been cooked up in the heart of an earlier generation of star.

Well, I've run across a factoid that's even neater. From Energies by Vaclav Smil, MIT Press 1999:

"High intensities of heterotrophic metabolism mean that living organisms surpass the Sun in power output per unit of mass.

Given the star's enormous mass (1.99 x 10 to the 33 g), its immense luminosity (3.9 x 10 to the 26 W) prorates to just about 200 nW/g of the stellar matter. In contrast, the daily metabolism of children (averaging about 3 mW/g of body weight) proceeds at a rate about 15,000 times higher, and respiring bacteria reach up to 100W/g, or 500 million times the Sun's rate. Stars astonish with their total energy fluxes, but ATP-driven energy conversions in heterotrophic organisms have unrivaled intensities of energy conversions per unit mass." (p.39)

In other words, not only are we made of stardust, but we burn brighter, too. I find that fact to be inexpressibly poignant.