by Miche GenestOh, the joy of making sourdough bread at home—building a starter, making a sponge, kneading the dough, shaping a loaf, waiting for it rise, baking it, letting it cool and finally, biting into a slice of freshly made bread slathered with good butter—ooh la la. But one of the special joys is the intimate and complicated relationship sourdough bakers develop with their starters. It’s like having a pet, bakers say, and indeed, they invent names for their starters, they check their starters into sourdough hotels when they travel, or leave strict instructions for house sitters NOT TO THROW IT OUT. They fret when the starter seems sluggish, they call their fellow bakers for sympathy and advice, they wake up in the middle of the night thinking oh no, I forgot to save a half-cup from the starter before I mixed the sponge! And they engage in endless debate about the strange and magical organisms living in a jar in their fridge. That wild yeast—is it present in the air, free floating or hanging out on the skin of fruits and vegetables, biding its time until the medium of flour and water comes out of the fridge and then diving in to start feeding? Or is that all a myth, and the yeasts are simply present in the flour? And what of the friendly bacteria, the strains of lactobacillus that enter into a symbiotic relationship with the yeast in the medium of flour and water, creating an acid environment inhospitable to bad bacteria that might spoil it—where does it come from? Well, it turns out that one of the places both yeast and bacteria come from is the baker’s hands. Ecologist Rob Dunn, author of several books (including Never Out of Season, How Having the Food We Want When We Want It Threatens Our Food Supply and The Future) conducted a controlled sourdough bake-off experiment with 15 bakers from around the world at the Puratos Centre for Bread Flavour in Belgium. Dunn and his fellow ecologist Anne Madden wanted to see if the microbes present on the baker’s hands influenced the bread. And it did. “There was an essence of the baker in the starter the baker made, and that was conveyed in the bread.” The other thing Dunn’s team discovered was that the baker’s hands looked very much like sourdough starter, that is, up to sixty percent of the microbes on the hands of the bakers were the same bacteria and yeasts found in sourdough starter, compared to three percent on the average human hand. As Dunn said, “…the bakers did influence their starters, but the other way around was true too. The life of baking seems to influence the bakers.” How cool is that? And if the baker’s hands look like sourdough, what do the cheesemaker’s hands look like? The farmer’s? The beekeeper’s? The full account of the experiment can be found in Dunn’s latest book, Never Home Alone, From Microbes to Millipedes, Camel Crickets and Honeybees, the Natural History of Where We Live.