Have you ever wondered how many people have lived on Earth and if the number of dead outnumber that of the living? When Arthur C Clarke wrote 2001: A Space Odyssey in 1968 he included this sentence, “Behind every man now alive stand 30 ghosts, for that is the ratio by which the dead outnumber the living.” This may seem amazing, but at the time of writing his book he was actually correct. But the population has clearly risen since 1968 and many more people have died also, so where do we stand today? Using some creative mathematics the approximate number of people who have ever lived on Earth is around 107 billion. That would mean that there are about 15 ghosts to every person who is alive today.
To get to this figure experts had to take an educated guess at the number of births per 1000 people and average life expectancy. This was difficult as for the majority of human existence there has been no accurate record keeping of any of this data, and changing trends, different geographical locations and natural events affected the figures. From the late 17th century the figures became easier to work with as more accurate records were being kept.
By starting at about 50,000 BC, when modern homo sapiens first appeared, we can begin to work out how many people have lived on Earth. By using all modern population data that is available from the late 17th century, and also assuming that the growth rates were constant in each period of time up until the modern ear, we can work out that roughly 107 billion people have lived on Earth.
Of course we could be wrong. So many different variables can meddle with these kind of estimates. Changes in environment, disease and even different migratory routes that our ancestors have taken throughout time will have an impact of how may people have lived on earth. The numbers that we are giving you should only be taken as a rough, and educated guess using all available resources.
So if you are a superstitious person, and afraid of ghosts, you really are wasting your time. With currently 15 ghosts to every living person, we could be haunted out of existence if they chose to.