Our Guts May Hate Mars
We can leave Earth. But will we always have to bring it with us?
You can grow a reasonably good tomato in water. But soil is a whole ecosystem, containing bacteria, protozoa, nematodes, insects, and much moreóand it supports us in many ways.
For one thing, soil bacteria appear to be important for maintaining the proper diversity and balance of microbiota (i.e., bacteria) in the human gut. Scientists say that the bacteria and tiny insects in soil provide ecosystem services
to humans and everything else on the planet. They break down the dead and the discarded, purify water, and cycle carbon dioxide into and out of the atmosphere.
Justin Sonnenburg, a microbiologist at Stanford, says that soil bacteria also enhance the quality of the foods grown in it. For instance, some of the microbes attack the plants. That may sound like a bad thing, but in fighting off those assaults, the plants generate compounds that are beneficial to human health, such as antioxidants. What it comes down to is this: Among other functions, good soil has bad bacteria that make plants do good things. We may be able to replicate some of these functions with technology, but if we donít know all
of the things that soil does, we may miss something important.
Martian colonists could probably live for years on food grown without soil. The question is, could they live on it for decades? Could their children grow up on it? Are there hidden hazards that would not become apparent until much later? To put these questions another way: Can we identify and reproduce the ecosystem services of Earth for a lifetime?