The End of October

by Lawrence Wright

In 2018, Suttle and other scientists looked on mountain peaks for evidence of viruses in the free troposphere, the concourse of jet travel just below the stratosphere. They were seeking an answer to a puzzle about the occurrence of nearly identical viruses in widely separated parts of the planet and vastly different environments. Was it possible that viruses—say, in dust or sea spray—could be swept into the atmosphere and transported from one continent to another? The scientists placed buckets on mountaintops in Spain’s Sierra Nevada, nine thousand feet high, and waited to see if viruses would rain into them. They were stunned by what they found. According to their calculations, more than 800 million viruses were deposited every day on every single meter of the earth’s surface. Most of these viruses preyed on bacteria, not humans. The total number of viruses on the planet was estimated to be a hundred million times more than the number of stars in the universe.