Most humans wonder about where we come from and why we are here. Astrobiologists get the unique opportunity to think about and research this question for a living. There are many interesting, and even science fiction like, hypotheses for the origins of life in the astrobiology community. These hypotheses are difficult to test since we cannot go back in time to the beginning of Earth to watch life emerge. Astrobiologists must instead make due by using models of the early Earth, lab experiments, and observing/studying life as we know it.
Early Earth’s climate was not a nice as it is today. Bombardment by space rocks, the formation of our moon, and a young Sun emitting large amounts of UV radiation created a situation that most of life today would consider inhospitable (Schwartz and Chang). Once the Earth cooled off, oceans began to form as its atmosphere evolved from a “solar nebula-derived gaseous envelope” (Schwartz and Chang) to something more familiar, but still inhospitable, to today’s life. With all of this less than welcoming climate at the surface of Earth, some believe Terran life developed farther away at the bottom of its oceans close to hydrothermal vents in contrast to Earth’s surface in warm tidal pools.
Hydrothermal vent’s discovery in 1979 (Corliss and Gordon) lead to some exciting science. There are weird, chemotrophic forms of life surrounding these vents. At face-value, an ordinary person would not think that this discovery would be useful for astrobiologists and other scientists studying the origins of life. Just a few years later in 1981 Corliss and his colleagues put out their hypothesis that life originated in these deep-sea vents. Hydrothermal vents provide a chemical source of energy, instead of light like most surface life, such as humans and plants, rely on. This chemical energy means that life did not need to get close to the unforgiving surface of a pre-biotic Earth. Deep-ocean vents are also rich in clays and minerals that provide the building blocks for life’s essential molecules such as amino acids, used to make proteins, purines, pyrimidines, and more (Miller and Lazcano).
There are still some issues with this hypothesis that scientists need to address and study more, just like all the other hypotheses we currently have about life’s origins. Hydrothermal vent’s extreme heat makes it difficult for some of cell’s building blocks such as ribose, a sugar used to make RNA, to stay stable for long (Miller and Lazcano). This presents an issue since some scientists currently believe that RNA was the fir information-carrying molecule in cells before DNA. This issue along with others present an opportunity for scientists to ask more questions, dig deeper, learn more, and what they do best, science!
Corliss, J.B and Edmond, Von Herzen, Ballard, . . . Van Andel. Gordon. "Submarine Thermal Springs on the Galapagos Rift." Science (1979): 1073-1083.
Miller, Stanley L. and Antonio Lazcano. "Formation of the Building Blocks of Life." Life's Origin: The beginnings of biological evolution. Berkely and Los Angeles: University of California Press, 2002. 100-103.
Schwartz, Alan W. and Sherwood Chang. "From Big Bang to Primordial Planet." Life's Origin: The beginnings of biological evolution. Berley and Los Angeles: University of California Press, 2002. 64-75. Book.
Thommes, Edward W. "Terrestrial planet formation." Pudritz, Ralph, Paul Higgs and Jonathan Stone. Planetary Systems and the Origins of Life. Cambridge: Cambridge University Press, 2007. 41-61. Book.