I am so surprised that, in a site visited by technical people, so many don't get that the rate of change is decreasing... Didn't any of you study Calculus? Did

I am so surprised that, in a site visited by technical people, so many don't get that the rate of change is decreasing... Didn't any of you study Calculus? Didn't you get the idea of "negative second derivative"? Yes, population is still growing in poor 3rd world countries. But even there it does at a rate far bellow what was 40 years ago.