While the theory of evolution is broadly accepted as fact among scientists, more controversy exists over explanations for the ultimate origin of life on Earth. However, new research published in Nature Ecology & Evolution sheds light on a potential theory for the origin of living things by attempting to recreate the conditions of the early earth and exploring how they could lead to the development of “protocells,” which are thought to be fundamental “building blocks” of all life. In an experiment, researchers successfully created conditions that led to the development of protocells by replicating the environment of underwater hydrothermal vents, whose combination of heat, alkalinity, and minerals are instrumental in the creation of protocells.
Though multiple competing theories explaining the origin of life exist, including Darwin’s assertion that life probably first evolved in shallow pools of warm water, the theory that life originally began within underwater thermal vents is supported by evidence, including the discovery of some of the world’s oldest fossils nearby these vents. Now, this explanation for the creation of life seems even more likely, as demonstrating the creation of protocells under these conditions is a key argument supporting the theory. Although the results of this research do not definitively prove that life on earth began in underwater hydrothermal vents, the researchers assert that the possibility of this explanation cannot be ruled out.
Hydrothermal vents are located deep under the Earth’s seas, where minerals from the planet’s crust react with seawater, creating a warm, alkaline, and hydrogen-rich environment. This process leads to the creation of so-called chimneys, which are rich with alkaline and acidic fluids, enabling the formation of complex organic compounds, including, as this new research shows, protocells. These vents emerge spontaneously along fault lines as a result of geological processes, and have existed on Earth for millions, if not billions of years. Hydrothermal vents are known for being areas of the deep sea where life is relatively abundant, as they tend to be populated by shrimp, worms, and clams, who feed off of the energy and materials present around the vents.
This research has strong implications not only for the beginning of life on Earth, but for the potential for life to form elsewhere in space.
Protocells are, in essence, the most basic form of a cell, consisting of a bilayer membrane around an aqueous solution. Previous experiments succeeded in creating these cells in cool, fresh water, but only under tightly controlled conditions. Also, previous experiments attempting to replicate hydrothermal vents have failed to generate protocells which don’t fall apart. In this most recent experiment, however, the scientists identified a flaw with previous research on creating protocells in hydrothermal vents; namely, these experiments used a limited number of types of molecules, whereas in natural environments, you would expect to see a wide range of different types of molecules.
Whereas it was previously thought that heat, alkalinity, and salt posed obstacles in the creation of protocells, this new research shows that these factors were actually beneficial in the process. This is because head allowed long carbon chains to form into a protocell structure, an alkaline solution helped protocells keep their electric charge, and saltwater helps fat molecules band together, forming more stable structures. What’s notable about this experiment is that while protocells have been created artificially in laboratory environments before, they had never been before created under conditions that match the chemistry of the early Earth.
This research has strong implications not only for the beginning of life on Earth, but for the potential for life to form elsewhere in space. This is because space missions have revealed the presence of similar hydrothermal vents on extraterrestrial bodies, including the icy moons of Jupiter and Saturn. Life on other planets or moons has not yet been discovered, of course, but research into the origins of life on Earth could give scientists a better idea of where in space to look for extraterrestrial life.