WE HAVE all heard tales of frogs, toads and fish raining from the heavens: these are rare events triggered by freak weather. But there are land and water-based life forms that seem to be present in the atmosphere just about all the time. These include algae, fungi and bacteria. What are they doing up there?
The late, great evolutionary biologist William Hamilton thought about this from the microbes’ point of view. In 1998, he argued that they were probably using the atmosphere as a dispersal medium (Ethology, Ecology and Evolution, vol 10, p 1). He had previously shown that…
