We think of natural selection as the kind of thing that happened long before people got involved. But one Soviet scientist believed that humans not only participated in a special kind of selection, but we ate better because of it.
When a harmless snake develops colors to look like a venomous snake, predators are wary and leave it alone. Butteflies come to resemble each other so they can all benefit from having a bitter taste. These are versions of mimicry that come to mind easily. They're also examples of a natural selection that has, for the most part, nothing to do with humans. Most examples have little to do with humans. Which is why the theories of Nikolai Vavilov were so surprising.