Counting Skeletons

From the Morton Collection of 19th Century Skulls. University Communications, University of Pennsylvania. via Flickr. In my previous dispatch, I described the reasoning behind demographer Carl Haub’s estimate that a whopping total of 108 billion people have lived and died since modern homo sapiens appeared. Since the current world population is about 7.1 billion, the old shibboleth that “more people are alive today than have ever lived” is wildly wrong. A lot of readers probably already knew that, but it was a surprise to me -- and to my editor -- when I first came across the number for a story I wrote for the New York Times. Haub may be off by several billion (he makes a good case that, if anything, his figure is an underestimate), but all I was really after was an order-of-magnitude calculation -- the right number of zeroes. For something so uncertain that is ...