This is a question that is periodically posed to library reference services. So, it came up today at our branch and I thought I'd post the answer here: according to the Population Reference Bureau, as of 2011, 107,602,707,791 people have been born in the world. Their video above explains the process of arriving at this figure, which is, naturally, a guesstimate since no hard population data exists for most of the time humans have been around. But it's an interesting parlor game of sorts, starting with establishing when the first humans even appeared. There's even a name for the study of ancient population studies - paleodemography.