How Much Storage Is Required to Store Every Word Ever Spoken by Human Beings?

A lot of people seem to be discussing this post speculating about how much storage space would be required to store every word spoken by every human being who has ever lived.

Apparently the standard answer repeated in a number of publications is that it can be done with a mere 5 exabytes. Mark Liberman points out that this is off by a factor of about 32 million. But Liberman’s calculations are also off due to an inaccurate assumption,

Second, the storage requirements for all human speech. There are said to have been 1 billion people in 1800, 1.6 billion people in 1900, and 6.1 billion people in 2000. So let’s assume that 10 billion people have lived an average of 50 years, speaking for 2 hours a day on average throughout their lives.

That is not a very good assumption for a number of reason. First, it assumes that the majority of human beings who have ever lived are alive today. Like the 5 exabyte claim, this is a commonly repeated myth.

Estimating the total number of human beings who have ever lived is obviously an inexact science, but the Population Reference Bureau estimates that the actual total is likely to be in excess of 100 billion. The problem is that people tend to think (as Liberman does) in terms of relatively recent history.

Homo sapiens probably goes back to about 50,000 BCE, but population doesn’t really take off until the agricultural revolution around 8,000 BCE. The Population Reference Bureau estimates that between 8,000 BCE and 1 AD, more than 46 billion human beings were born. From 1 AD to about 1200 AD, about another 26 billion people were born.

Another factor that would have to be included here, however, would be average life span — especially given infant and childhood mortality rates that are still high in some parts of the world. Fifty is probably a bit too high (it’s not that people didn’t live to be 50 in the 19th or 12th or even 1st century, but that so many people died before reaching their fifth birthday).

But suffice it to say that the total storage space is significantly higher than even Liberman’s estimates.


How Many People Have Ever Lived on Earth? Carl Haub, Population Reference Bureau, November/December 2002.

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