Ever on the hunt for a good ecological metaphor, I enjoyed David Mann’s suggestion that we should try missing out every fifth breath we take in order to appreciate the contribution that diatoms make to global productivity. Approximately 20% of the oxygen that we breathe comes from diatoms, principally in the world’s oceans. You can see the whole article here: http://www.scotsman.com/news/little-word-about-the-mighty-diatom-1-3227674.
Paul Falkowski of Rutgers University, New Jersey makes an even greater claim for the impact of diatoms on humans: put simply, we would not be here without them. His reasoning goes something like this: oxygen concentrations in the atmosphere have approximately doubled over the past 205 million years, a consequence, he argues, of the evolution of the diatoms and coccolithophorids. This increase in oxygen concentrations, in turn, facilitated the expansion and diversification of mammals, who depend upon the transfer of oxygen across the placenta. Higher oxygen concentrations allows larger mammals to evolve and survive. Ergo … no diatoms, no humans.
Falkowski, P.G., Katz, M.E., Milligan, A.J., Fennel, K., Cramer, B.S., Aubry, M.P., Berner, R.A., Novacek, M.J. & Zapol, W.M. (2005). The rise of oxygen over the past 205 million years and the evolution of large placental mammals. Science (New York) 309: 2202-2204.