Evolution :- Theory of ORIGIN OF LIFE | Special Creation, Big-Bang, Biogenesis & Abiogenesis

   • Evolution :- Theory of ORIGIN OF LIFE | Sp...  

📑 Chapter :- Evolution (उद्विकास)
🫧 Topic :- Origin of Life (जीवन की उत्पत्ति)

🔘 Theory of Special Creation
🔘 Theory of Spontaneous Generation
🔘 Theory of Biogenesis
🔘 Cosmozoic Theory
🔘 Panspermia Theory
🔘 Theory of Chemical Evolution
🔘 Miller's Experiment

he origin of life on Earth stands as one of the great mysteries of science. Various answers have been proposed, all of which remain unverified. To find out if we are alone in the galaxy, we will need to better understand what geochemical conditions nurtured the first life forms. What water, chemistry and temperature cycles fostered the chemical reactions that allowed life to emerge on our planet? Because life arose in the largely unknown surface conditions of Earth’s early history, answering these and other questions remains a challenge.

Several seminal experiments in this topic have been conducted at the University of Chicago, including the Miller-Urey experiment that suggested how the building blocks of life could form in a primordial soup.

Earth is about 4.5 billion years old. Scientists think that by 4.3 billion years ago, Earth may have developed conditions suitable to support life. The oldest known fossils, however, are only 3.7 billion years old. During that 600 million-year window, life may have emerged repeatedly, only to be snuffed out by catastrophic collisions with asteroids and comets.

The details of those early events are not well preserved in Earth’s oldest rocks. Some hints come from the oldest zircons, highly durable minerals that formed in magma. Scientists have found traces of a form of carbon—an important element in living organisms—in one such 4.1 billion-year-old zircon. However, it does not provide enough evidence to prove life’s existence at that early date.

Where did life on Earth begin?

Two possibilities are in volcanically active hydrothermal environments on land and at sea.

Some microorganisms thrive in the scalding, highly acidic hot springs environments like those found today in Iceland, Norway and Yellowstone National Park. The same goes for deep-sea hydrothermal vents. These chimney-like vents form where seawater comes into contact with magma on the ocean floor, resulting in streams of superheated plumes. The microorganisms that live near such plumes have led some scientists to suggest them as the birthplaces of Earth’s first life forms.
Organic molecules may also have formed in certain types of clay minerals that could have offered favorable conditions for protection and preservation. This could have happened on Earth during its early history, or on comets and asteroids that later brought them to Earth in collisions. This would suggest that the same process could have seeded life on planets elsewhere in the universe.

What are the ingredients of life on Earth?

The recipe consists of a steady energy source, organic compounds and water.

Sunlight provides the energy source at the surface, which drives photosynthesis. On the ocean floor, geothermal energy supplies the chemical nutrients that organisms need to live.




There are several theories for how life came to be on Earth. These include:

Life emerged from a primordial soup

As a University of Chicago graduate student in 1952, Stanley Miller performed a famous experiment with Harold Urey, a Nobel laureate in chemistry. Their results explored the idea that life formed in a primordial soup.

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. Then they passed electrical sparks through the container to simulate lightning. Amino acids, the building blocks of proteins, soon formed. Miller and Urey realized that this process could have paved the way for the molecules needed to produce life.
Scientists now believe that Earth’s early atmosphere had a different chemical makeup from Miller and Urey’s recipe. Even so, the experiment gave rise to a new scientific field called prebiotic or abiotic chemistry, the chemistry that preceded the origin of life. This is the opposite of biogenesis, the idea that only a living organism can beget another living organism.