If you make your own yogurt, there's a chance your yogurt could outlive you.
That's because some bacteria that grow and feed on the sugar in milk – the process that ferments milk into yogurt — can procreate indefinitely in new generations of yogurt.
But not all yogurts have these immortal powers. The typical store-bought yogurt only carries a few strains of bacteria that have been isolated by scientists. Those bacteria on their own can't regenerate very long – maybe just a generation or two.
That's one reason yogurt enthusiasts are now rediscovering heirloom yogurt starters, many of which originated in countries like Finland and Bulgaria with long traditions of yogurt-making. These bacterial cultures, which live on in yogurt or in freeze-dried powders now sold by one company, are made up of diverse communities of bacteria that together can take over one batch of milk after another.