India, March 4 -- The findings could help understand how single-cell organisms first emerged on Earth, according to scientists

Earth may have been covered by a global ocean that turned the planet into a "water world" more than three billion years ago, according to a study published in Nature Geoscience .

The findings could help scientists to better understand where and how single-cell organisms first emerged on Earth.

According to the paper, the origin and evolution of Earth's biosphere were shaped by the physical and chemical histories of the oceans.

Marine chemical sediments and altered ocean crust preserve a geochemical record of these histories. That is, they hold clues about the seawater that covered Earth at that time.

The auth...