Somewhere in the back of our monkey brains, we knew that violin bows were made with horsehair. Really we did. But this video was an incredible reminder: watch this quartet play on instruments using bows made with human hair.

Cream Silk Hair shampoo, a Unilever brand in the Philippines, tested the promise of its "anti-breakage" shampoo by making violin bows out of human hair -- but this was no quickie stunt. The quartet played a 4-hour, 40-song concert with the human hair-strung instruments. And... it's incredible. Go ahead-- watch and listen: