Chapter 3 - Extreme Life

Chapter 3
        We imagine ourselves as Earth’s rugged generalists, but in truth we are frail. We share the planet with microbes that would be at home in boiling water or deep rock or pure salt or battery acid. Their diverse forms are represented in spectral color. Life has radiated into every conceivable environmental niche. Robust is biology’s middle name—it’s our fragility that is unusual.
        The binding of life is DNA. This delicate molecular ladder both codes and transmits information, and whatever experimentation might have taken place on the primeval Earth, organisms using DNA superseded and consumed all others. As James Watson once said, “Life is digital information.” A base pair is like a letter, a gene is like a sentence, the genome is like an encyclopedia, and all aspects of the organism are coded in genetic material and its complex interactions with the environment. The concept of life as information leads to the possibility of artificial life: life without carbon and water. Biologists are tinkering with molecular Legos in the lab, trying to improve on nature and built an organism from scratch. Humans are heading towards a post-biological future, when we pass through the membrane of progress where technology usurps the organism. There is tension between the reductionist view of life fostered by genetics and our suspicion that there is something special about the spark of life.
        Humans are temporary visitors in an overwhelmingly microbial world. The modern tree of life based on DNA places us and all animals as a peripheral twig. Genetic diversity and complexity at the microscopic level is amazing. We are not so special—we share half our DNA with yeast. There are more microbes in our gut than there are people on the planet, and there is more microbial DNA in a teaspoon of seawater than in the human genome. The extremophile microbes thrive in places we can’t live: in pores deep within rocks, bathed in acidic runoff from an abandoned mine, rapidly repairing their radiation-damaged DNA in the shadow of a nuclear reactor. We can visualize water bears no bigger than the head of a pin, albino fish foraging near an undersea volcano, and pink sea worms undulating from a sheet of methane ice on the ocean floor.
        All this is one planet: Earth. Life beyond Earth might not only be stranger than we imagine, it might be stranger than we can imagine. Rumpled bed sheets suggest landscapes and the contours of the imagination. Our biology may just be one solution for life, a pleasant valley but not the only dwelling place, and not necessarily the best of all possible worlds. In the prodigious biological possibility of the universe, some versions may be wildly different.

About the Artist


Heather Green is a graduate student in the College of Fine Arts at the University of Arizona and a second generation Tucsonan. Her current work is informed by her lifelong relationship with the headland of La Cholla near Puerto Peñasco, Mexico, a passion for old science books, and her love of the natural world. She has designed exhibits about sustainable fisheries and materials for conservation initiatives, and is currently developing a virtual museum about La Cholla.

Chapter 3

Extreme Life

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