You've probably heard something along the lines of "There are as many people alive today as have ever lived in the past." This turns out not to be true, not even close.
The claim is that the total number of people who have ever been born is over 100 billion. In other words, the current population is only about 6% of the total.
Perhaps even more surprisingly, the best guess for the number of people who had been born by 1 A.D. is 50 billion. (The comparative slowness in growth since then is attributed, in large part, to the bubonic plague.)