I always find this statistic about the number of people who ever lived to be incredible. It means that 6.5% of everyone who ever lived is alive right now. For me, that fact helps explain the incredible pace of change observable in every facet of civilization. There is an awesome amount of our humanity's intelligence on display at this very moment.

Then, when you consider how a lot of the 6.5% live (i.e. with extreme poverty and hunger), we are not even remotely reaching our collective capacity. The pace is going to get even faster as we achieve the Millenium Development Goals.