Earth's human population is projected to hit 7 billion by the end of 2011. That's a pretty big number, but it pales in comparison to this amazing finding: every cubic meter of air could be home to up to 100 million microorganisms. Noah Fierer, a biologist at the University of Colorado, Boulder, is hoping to map their habitats.
Biologists have known for a long time that the air is teeming with life; airborne bacteria are actually one of the surfaces on which water vapor condenses to form clouds. (The same is true of snowflakes.) It's not so much its existence as its incredible diversity that's surprising. As Vanessa Schipani explains at The Scientist, new DNA sequencing technologies have helped researchers measure airborne biodiversity. In urban areas, life in the air is roughly as diverse as life in the soil.
Two questions now need to be answered. First, is the air just a temporary home for microbes - or is it an actual long-term habitat? Second, how does the large-scale presence of life in our atmosphere affect other processes, like weather or soil cycles? Fierer aims to sample the air in around two hundred locations nationwide, developing a data set that could be used for further research.
In a way, one can't be too surprised by discoveries like these - everywhere you look, there's life of some kind. Robert Hooke, whose 1665 book Micrographia first brought microscopic images to the world's attention, wrote of the Earth that "in every little particle of its matter, we now behold almost as great a variety of creatures as we were able before to reckon up on the whole Universe it self." Incredibly, it's as true now as it was then.
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