A guide to geobiological and astrobiological study

By JAEMIE BENNETT | December 7, 2017

Here I am, writing a column about astrobiology and geobiology, and I realize I never did one crucial thing: explain what this super specific field of science actually is. What’s the point of reading about interesting discoveries if there’s no context? So what is astrobiology? What is geobiology?

Let me start by saying, I had no idea either. I always thought of myself as a DNA person; I imagined studying genomes, mapping them out, discovering proteins like CRISPR-cas9.

But then I started watching shows on exoplanets and the potential for life and reading articles that hypothesized life didn’t actually start near underwater thermal vents. Gradually, I found myself thinking about the relationship between organisms and their environment much more than the little nucleotides hiding away in a nucleus.

After a little bit of soul searching and stumbling through the internet, I found out my interests have a name: geobiology and astrobiology.

Astrobiology is the better defined and more straightforward of the two: It’s the study of life beyond the organisms currently on Earth. It includes extraterrestrial life, the origins of life on Earth and, hypothetically, synthetic life.

The term “astrobiology” was first used by Soviet astronomer Gavriil Tikhov, who is the namesake for an asteroid and craters on the moon and Mars.

The study of astrobiology relies on a few crucial ideas. One is that extraterrestrial life will be carbon-based, just as terrestrial life is. It may seem naïve to believe extraterrestrial organisms would be built similar to us, but the theory is based in fact.

Carbon is one of the only elements that can readily bind with other elements, and the fact that it can bind to itself allows for the creation of long chains of atoms to create complex compounds. Carbon is also the fourth most abundant element in the universe, making it a logical candidate for being at the heart of extraterrestrial biology.

Another idea is that possibly habitable planets must have water. Water is a crucial solvent in many terrestrial biological processes, so the search for exoplanets that might house life largely hinges on that planet’s ability to retain liquid water.

The search for habitable exoplanets also revolves around that planet orbiting a sun-like star. It is believed that a sun is required as an energy source for life to begin and thrive.

Red dwarf stars are a likely candidate to house planetary systems with viable planets, since they have long enough lifespans for planets to be formed and perhaps cultivate life and are also the most abundant type of star in the universe.

Today, astrobiology is carried out in two main fields. One is the study of extremophiles, which examines life in the harshest conditions on Earth and draws analogies to extraterrestrial environments.

The other is the search for habitable exoplanets, which largely involves finding planets and studying what we can about their atmospheres and conditions that could point to life.

Geobiology is slightly less defined but no less interesting. Essentially it studies the relationship between organisms and their environment, focusing on the relationship over space and time.

Geobiology is incredibly interrelated with many other disciplines, including ecology, evolutionary biology, microbiology, paleontology and biogeochemistry.

The term “geobiology” was coined by Dutch biologist Lourens Baas Becking, who is largely remembered for the Baas Becking Hypothesis.

Baas Becking stated that “Everything is everywhere, but the environment selects,” essentially describing half of current geobiology. From evolutionary perspective, the organism that survives to pass down its genes is the most resilient to the environment it lives in.

The other half of geobiology is basically the opposite thought process; the environment may affect organisms, but organisms also change the environment. The most significant example of this in Earth’s history is the Great Oxygenation Event, when photosynthetic cyanobacteria pumped large quantities of oxygen into Earth’s atmosphere.

This significantly changed the environment, likely killing off organisms that were poisoned by oxygen and beginning oxygen-dependent processes that may have dramatically changed the course of terrestrial life.

Simply, geobiology studies the coevolution of life and the Earth, looking at how each affect the other over time.

Astrobiology and geobiology are both relatively new fields and, as much of science is, contain loose borders that blend into many divisions of science. However, they both address what I believe is the most important goal of science: the fundamental understanding of life.

Clearly, that is a tall order for science to fulfill, but we are constantly moving into new ages of exploration and discovery that give me hope for an answer. The universe may have had a few billion years head start on understanding how life is possible, but who would we be if we didn’t try?

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