One of the most interesting discoveries of my life time has been the existence of exotic life forms on Earth, including extremophiles, which thrive in environments that our own relatives cannot tolerate at all. With every year, we find life everywhere on this planet, both side-by-side with “normal” life (e.g., living in our mouths) and in “impossible” places like hot springs, under ice caps and underground.
These life forms are very distantly related to us, with completely different physiologies that do not need (or like) Oxygen or sunlight. However, these guys do share one aspect of our biology: most of them are Carbon-based. (OK, there may be a lot of Silicon- or other based life on Earth, too, but we don’t really know about it.)
These days we are very concerned with getting a handle on the Earth’s Carbon inventory, because we Homo “sapiens” have been dumping huge amounts of Carbon into the atmosphere, with potentially dramatic effects. It’s a bit late, but we’d like to know where Carbon is and how it moves around absent the gormless actions of humans.
So it is extremely interesting and important to find out just how much of this extremophile life there actually is.
This fall researchers form the wonderfully names Deep Carbon Project report a new estimate that something like 10^29 cells live in the Earth’s crust. (Actually, the new estimate is for life under continents, but the new estimate is in the same ball park as previous estimates of undersea crust.) That’s right, in rock and underground water and whatever. This is a big number—ten times the population of the world’s oceans, for example.
Obviously, life is different down there than on the surface. No sunlight, but a lot of heat. Pressure and dense, solid materials. And who knows what else. By our parochial standards, it’s rough, not to say fatal. Nevertheless, they persist.
There are so many interesting questions. For one thing, just how are these guys related to our surface loving relatives. Obviously, we all evolved at the same time on the same planet. But do we migrate and interact upstairs and downstairs? Did life start below and migrate up, or at the surface and migrate down, or both? And, for that matter, how does underground life reproduce and move and who eats who (and how)?
Of course, the big story is that this planet is absolutely saturated with life, even deep down. Among other things, this suggests that other planets and moons could be saturated with much more life that we have suspected based on surface conditions. If microbes can live deep in rock here, then they could live deep in the rock on Mars, or even Venus or other places. Who knows?
These estimates also tell us that a whole lot of Carbon is sequestered in these species.
The good news is that human activity probably isn’t having much effect on these guys. We may be screwing up the surface, the atmosphere, and the oceans, but we’re not really harming the crust (yet?). This means that life on Earth will probably survive the big Anthropocene die off, at least underground.
The bad news is that even messing with a tiny fraction of biosphere, we seem to be pushing the surface to significant changes that will not be good for those of us living on and near the surface. Even if vast amounts of Carbon are sequestered underground, that apparently isn’t going to save our skins. Life may survive, but we are working hard to kill ourselves and all our closest biological relatives.
The not quite so bad news is that if we somehow get these underground species to perk up and expand a relatively little, that might suck a lot of Carbon out of the atmosphere. (The Carbon Cowboy’s have made this very argument relating to just the species near the surface in the soil–so imagine if the Deep Ones were to help!)
So cool! This makes me want to take up biology!
- Jonathan Amos, Amount of deep life on Earth quantified, in BBC News – Science & Environment. 2018. https://www.bbc.com/news/science-environment-46502570
- Deep Carbon Project, Life in Deep Earth Totals 15 to 23 Billion Tonnes of Carbon—Hundreds of Times More than Humans in Deep Carbon project,. 2018. https://deepcarbon.net/life-deep-earth-totals-15-23-billion-tonnes-carbon
- JoAnna Klein, Deep Beneath Your Feet, They Live in the Octillions, in New York Times. 2018. https://www.nytimes.com/2018/12/19/science/subsurface-microbes.html
- C. Magnabosco, L. H. Lin, H. Dong, M. Bomberg, W. Ghiorse, H. Stan-Lotter, K. Pedersen, T. L. Kieft, E. van Heerden, and T. C. Onstott, The biomass and biodiversity of the continental subsurface. Nature Geoscience, 11 (10):707-717, 2018/10/01 2018. https://doi.org/10.1038/s41561-018-0221-6