It's alive! The irresistible rise of yeast

When the bread baking craze took off during the pandemic, many of us encountered sourdough starter for the first time: a concoction of flour and water playing host to a colony of micro-organisms — most importantly: yeast. Without this single-celled fungus, we would have no leavened bread, no wine, no beer and no spirits. So, what role does it play? And how long have humans partnered with this miraculous organism?