India: 2 Billion-Year-Old Fossils of Earth's Earliest Life Form Discovered

earlyearth
Artist's rendering of early Earth's surface. NASA

A scientist in India found microfossils that have been dated to be a staggering 2 billion years old. The prokaryotic fossils represent the planet’s oldest-known form of life.

Naresh Ghose, a Bengaluru-based geologist, made the discovery on the Indian subcontinent in the Gwalior basin of the Bundelkhand region near Jhansi. He reported the findings at the recent annual convention of the Indian Geological Congress in Nagpur.

Microfossils refer to fossils smaller than 1 millimeter in size and which require a microscope to study. According to the Indo-Asian News Service, Ghose told the convention audience that the shape of these particular microfossils, along with the pattern in which they were distributed, strongly suggest they belonged to a micro-organism.

Prokaryote_cell A prokaryotic bacteria cell. Wikipedia

Prokaryotes are bacteria, usually single-celled, and without a nucleus. They were the planet’s only life form for most of its history, explains Jere H. Lipps, Director of the University of California Museum of Paleontology, in an explainer for the museum's website. They first arose about 3.5 billion years ago, though what happened after that, in terms of when exactly they began to evolve into eukaryotes, or more complex forms of life, is unclear. Prokaryotes have been found in rocks as old as 3 billion years; earlier this year, scientists discovered 1.6 billion-year-old eukaryotes in a sedimentary basin in central India.

"The present study reports for the first time the presence of 'organogenic' microfossils—derived from living organisms—in black shale immediately underlying the volcanic rock of the Gwalior basin," IANS reported Ghose as saying. "Therefore, the microfossils ... may be regarded as the confirmed oldest existence of life dated about 2,000 million years ago ever to be recorded from the Indian subcontinent.”

Ghose had been analyzing sections of sediment there that were particularly thin, and that contained a mix of black shale, limestone, and particles from ancient rivers and volcanoes. Black shale, which is heavily exported in the United States as a source of natural gas, is associated with organic material.

The appearance of such primitive life within the shale lines up with the “Great Oxygenation Event,” which according to an unrelated 2016 paper published in the journal Science Advances, refers to the rapid increase in our atmosphere's level of oxygen (within just 1 to 10 million years) that allowed life to develop and diversify.

Ghose, a former geology professor at Patna University, also offered some remarks that could be encouraging for citizen scientists.

"This important discovery was made using a simple and inexpensive device like a microscope without the aid of any sophisticated instrument," Ghose said at the conference, according to IANS.