How many humans have there occupied the earth over the past 1.5 million years?

Question

The general consciences seems to be that humans have occupied the earth for 1.5 million years. Given all the variables (e.g. war, disease, etc.) how many have reached adulthood - lets say 21 years old?

Answer 1

nearly 200,000,000,000

(roughly 198 Billion)

Answer 2

That's impossible to know. There hasn't been a general census of the number of people on the planet until recently - we don't have any clue how many people existed in the americas until the 15th century, and records of the number of people in the 'old world' are few and far between (and they only go back to ancient times). Certainly the average life expectancy has increased over the years, but the population size has grown and decreased depending on too many factors to count.

Answer 3

That is a good estimate to guess at. I would say that the figure has steadily increased.