Question

The origin of life on earth dates back to

• A. 6000 million years
• B. 4500 million years
• C. 2000 million years
• D. 10,000 million years

Answer 1

The correct option is B 4500 million years

It is generally agreed that all life today evolved by common descent from a single primitive lifeform. We do not know how this early form came about, but scientists think it was a natural process which took place perhaps 3,900 million years ago. A scientific study from 2002 shows that geological formations of stromatolites 3.45 billion years old contain fossilized cyanobacteria. It is now widely agreed that stromatolites are oldest known life form on Earth which has left a record of its existence. Therefore, if life originated on Earth, this happened sometime between 4.4 billion years ago, when water vapor first liquefied and 3.5 billion years ago.

Therefore, the correct answer is option B.