 And I think it's actually an important idea for economics as well. So I'll start with the biology. The bottleneck is where a population arbitrarily gets reduced to a very small number. And the number of people in that population could be 10, it could be 100, whatever it is. But who those 10 or 100 people are really, really matter. Human society has had bottlenecks at various times. We don't know exactly how small they've been, but the hypothesis is perhaps that it may have been as few as a few thousand humans at one point.