AP BIOLOGY

Detailed explanation-1: -We know that life began at least 3.5 billion years ago, because that is the age of the oldest rocks with fossil evidence of life on earth. These rocks are rare because subsequent geologic processes have reshaped the surface of our planet, often destroying older rocks while making new ones.

Detailed explanation-2: -Researchers have discovered organic molecules trapped in incredibly ancient rock formations in Australia, revealing what they say is the first detailed evidence of early chemical ingredients that could have underpinned Earth’s primeval microbial life-forms.

Detailed explanation-3: -Researchers at UCLA and the University of Wisconsin–Madison have confirmed that microscopic fossils discovered in a nearly 3.5 billion-year-old piece of rock in Western Australia are the oldest fossils ever found and indeed the earliest direct evidence of life on Earth.

Detailed explanation-4: -The earliest evidence of life on Earth comes from fossils discovered in Western Australia that date back to about 3. 5 billion years ago. These fossils are of structures known as stromatolites, which are, in many cases, formed by the growth of layer upon layer of single-celled microbes, such as cyanobacteria.

Detailed explanation-5: -The oldest known fossils, in fact, are cyanobacteria from Archaean rocks of western Australia, dated 3.5 billion years old. This may be somewhat surprising, since the oldest rocks are only a little older: 3.8 billion years old!