It's hot today. Really, really, hot; over a 100 degrees Fahrenheit hot, and so I'm sweating.
Sweating is what we people do to cool off, which is good. But sweating is also what makes me ... what's the word? Odoriferous. (Latinate for stinky, which is not so good.)
Here's my question: If I swipe a little sweat trickling down my leg and hold it to my nose, it smells fine. But if I take a swipe from my arm pit (or several other places I choose not to mention) it's very un-fine. Why the difference?
Why does sweat sometimes smell and sometimes not?
The answer comes from my Radiolab pal Josh Kurz (here working for Distillations, a chemistry podcast sponsored by Chemical Heritage magazine). In this very sweaty video, featuring a warmly clad Louis Pasteur, Josh discovers that sweat, when it's just plain sweat, doesn't smell. But sometimes sweat bonds with a particular group of proteins, and it's those proteins that smell, not the sweat. You'll see. Just hold your nose.
If you haven't sweated enough, last year cartoonist Lev Yilmaz and I teamed up on a cartoon video that asked, How Much Heat Can A Person Stand? We describe an experiment conducted by several British gentlemen 200 years ago and their very surprising discovery which, once again, was all about sweat. (And also involved a dog, an egg and a steak.) Josh Kurz's videos are part of a Distillation series called Blood, Sweat and Tears. He's doing a video about each.