When did life originate on Earth?

Correct option is B

​The correct answer is(b) 3.8 billion years ago​

Life is believed to have originated on Earth approximately 3.8 billion years ago during the Archean Eon. Evidence comes from microfossils, stromatolites, and isotopic signatures of ancient carbon found in rocks. The earliest forms of life were simple single-celled organisms, such as prokaryotes (bacteria and archaea). They thrived in Earth's primitive conditions, which included a reducing atmosphere composed of gases like methane, ammonia, water vapor, and hydrogen. These organisms likely obtained energy from chemical reactions rather than sunlight, as oxygen was not present in the atmosphere at the time.

Information Booster:

● The first life forms were anaerobic (surviving without oxygen).
● Cyanobacteria, which appeared later, contributed to oxygenation of the atmosphere through photosynthesis.
● The origin of life is theorized to involve abiogenesis, where simple organic molecules combined to form complex biomolecules.
● Experiments like the Miller-Urey experiment simulated early Earth conditions and showed that organic molecules could form spontaneously.
● The "Last Universal Common Ancestor" (LUCA) is the theoretical ancestor of all life on Earth.

Additional Knowledge:

• (Option A) 6 million years ago: This marks the approximate divergence of humans from chimpanzees, not the origin of life.
• (Option C) 4.9 million years ago: Incorrect timeframe; associated with the evolution of early hominins, not the origin of life.
• (Option D) 6 billion years ago: This predates Earth's formation, as Earth is approximately 4.5 billion years old.