![]() Instead, they suggest that these ingredients came from meteorites or comets. Some scientists think that some of the molecules important to life may be produced outside the Earth. This is the opposite of biogenesis, the idea that only a living organism can beget another living organism. Even so, the experiment gave rise to a new scientific field called prebiotic or abiotic chemistry, the chemistry that preceded the origin of life. ![]() Scientists now believe that Earth’s early atmosphere had a different chemical makeup from Miller and Urey’s recipe. Miller and Urey realized that this process could have paved the way for the molecules needed to produce life. Amino acids, the building blocks of proteins, soon formed. Then they passed electrical sparks through the container to simulate lightning. Miller and Urey injected ammonia, methane and water vapor into an enclosed glass container to simulate what were then believed to be the conditions of Earth’s early atmosphere. Their results explored the idea that life formed in a primordial soup. These include:Īs a University of Chicago graduate student in 1952, Stanley Miller performed a famous experiment with Harold Urey, a Nobel laureate in chemistry. There are several theories for how life came to be on Earth. What are the major scientific theories for how life emerged? To explain its presence on Earth, one theory proposes that a class of meteorites called carbonaceous chondrites formed far enough from the sun to have served as a water-delivery system. ![]() Water now covers about 70% of Earth’s surface, but how much sat on the surface 4 billion years ago? Like carbon and nitrogen, water is much more likely to become a part of solid objects that formed at a greater distance from the sun. So, how did the small amounts found at the surface get there? Could a similar process also have unfolded on other planets? Gold also bonds more often with metal, so most of it ends up in the Earth’s core. That’s because carbon chemically bonds more often with iron than rock. Also, carbon, like gold, is rare at the Earth’s surface. These elements become solid only under very cold temperatures, such as exist in the outer solar system, not nearer to the sun where Earth is. For example, scientists would not expect a planet that formed so close to the sun to naturally incorporate carbon and nitrogen. But there are several scientific mysteries about how these elements wound up together on Earth. For us, these are carbon, hydrogen, oxygen, nitrogen, and phosphorus. On the ocean floor, geothermal energy supplies the chemical nutrients that organisms need to live.Īlso crucial are the elements important to life. Sunlight provides the energy source at the surface, which drives photosynthesis. The recipe consists of a steady energy source, organic compounds and water. What are the ingredients of life on Earth? This would suggest that the same process could have seeded life on planets elsewhere in the universe. This could have happened on Earth during its early history, or on comets and asteroids that later brought them to Earth in collisions. Organic molecules may also have formed in certain types of clay minerals that could have offered favorable conditions for protection and preservation. The microorganisms that live near such plumes have led some scientists to suggest them as the birthplaces of Earth’s first life forms. These chimney-like vents form where seawater comes into contact with magma on the ocean floor, resulting in streams of superheated plumes. The same goes for deep-sea hydrothermal vents. Some microorganisms thrive in the scalding, highly acidic hot springs environments like those found today in Iceland, Norway and Yellowstone National Park. Two possibilities are in volcanically active hydrothermal environments on land and at sea. However, it does not provide enough evidence to prove life’s existence at that early date. Scientists have found traces of a form of carbon-an important element in living organisms- in one such 4.1 billion-year-old zircon. Some hints come from the oldest zircons, highly durable minerals that formed in magma. The details of those early events are not well preserved in Earth’s oldest rocks. During that 600 million-year window, life may have emerged repeatedly, only to be snuffed out by catastrophic collisions with asteroids and comets. ![]() The oldest known fossils, however, are only 3.7 billion years old. Scientists think that by 4.3 billion years ago, Earth may have developed conditions suitable to support life. What research are UChicago scientists currently conducting on the origins of life?Įarth is about 4.5 billion years old. ![]() What is chirality and why is it biologically important?.What are the major scientific theories for how life emerged?.What are the ingredients of life on Earth?. ![]()
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