Just a week after Science magazine revealed life one mile below the sea floor, today's issue of Nature carries a paper demonstrating surprisingly rich biodiversity on the sea floor even in the absence of hot springs.
Katrina Edwards and colleagues at the University of Southern California have analysed samples from the basalt seam along the mid-Pacific spreading zone. They found microbial biodiversity by several orders of magnitude higher than in the water column above the sites, and comparable even to soil.
The researchers calculated how much biomass could theoretically be supported by chemical reactions with the basalt. They then compared this figure to the actual biomass measured. “It was completely consistent,” Edwards said.
Expect the usual press coverage about how life could have originated down there, and so on. But what I find most intriguing is that 30 years after the discovery of black smokers, the frontiers of life on Earth are still sufficiently blurred to come up with two major surprises in the space of of a week. So in all honesty, we should admit that we still don't know where the limits of life on Earth really are. And this makes it difficult to predict where life may or may not be possible in the rest of the Universe.