Do the dead outnumber the living?

The population of the planet reached seven billion in October, according to the United Nations. But what’s the figure for all those who have lived before us?

It is often said that there are more people alive today than have ever lived - and this “fact” has raised its head again since the UN announcement about the planet’s population reaching a new high.

The idea helps fuel fears that the population is expanding too fast.

It is true that if you delve back into the mists of time, the population of Earth was tiny in comparison to today and logically it might seem plausible that the living outnumber the dead.

It is agreed by most demographers that the UN figure for the number alive today is reasonably accurate. The problem is, how do you calculate how many have ever lived, and where do you start?