A New York article about the suicide of a Dalton student contains this interesting observation. The dead boy
left filthy socks (which smelled, a cousin said, like kimchi) on his pillow
From which I conclude not only that kimchi is a good source of bacteria (“fermented foods” is a vague category — fermented for how long? — that might contain poor sources of bacteria) but also that our olfactory systems are good at detecting bacteria or more precisely bacterial byproducts. (Kimchi and used socks involve vastly different bacteria but are lumped together.) We don’t use smell to avoid predators or find food. We use vision and hearing for that. Maybe we use smell mainly to decide what to eat — to decide what contains calories (by learning smell-calorie associations, the basis of the Shangri-La Diet) and, as this observation suggests, what contains bacteria.