On the evolutionary tree, humans diverged from yeast roughly 1 billion years ago. By comparison, two seemingly similar species of bacteria, Escherichia coli and Bacillus subtilis, have been evolving apart for roughly twice as long. In other words, walking, talking bipeds are closer on the tree of life to single-celled fungi than these two bacteria are to one another. In fact, it’s becoming increasingly clear that what is true of one bacterial type may not be true of another — even when it comes down to life’s most basic biological…
