New Delhi, Nov. 3: Sankar Chatterjee, an Indian-origin palaeontologist in America widely known for his work on the evolution of flight in birds and the extinction of dinosaurs, is now pursuing a new frontier in science: the quest for the origin of life.

Chatterjee, a professor of geosciences at the Texas Tech University, has put together a theory for the origin of life on Earth that ties the emergence of the earliest single-cell organisms with the hellish conditions on an infant planet.

In a paper presented earlier this week at a scientific meeting of the Geological Society of America in Denver, Colorado, Chatterjee has connected longstanding ideas about the chemical precursors of life to impact craters that he says served as “crucibles” for the emergence of the earliest life forms.

He has proposed that meteorites and comets that battered the Earth during its infancy brought some building blocks of life and created environments where these chemicals were churned through processes that eventually gave rise to single-cell organisms.

“Life appears to have originated near the tail-end of the most violent period of the Earth’s history,” Chatterjee told The Telegraph over the phone. “Not in a calm and tranquil pond.”

SANKAR CHATTERJEE

In 2010, Dinosaur Man Sankar Chatterjee had picked up two trophies — the Shera Bangali and the Sherar Shera given by ABP Ananda — in Calcutta where he was honoured for his contribution to geoscience. “Dinosaurs weren’t foolish. They ruled the earth for 160 million years. Had there not been a natural calamity, dinosaurs would have been still around and I wouldn’t have been on this stage today!” a smiling Chatterjee had said then

MOLTEN EARTH

The most violent period on Earth — 4.5 to 4 billion years ago

PRIMORDIAL SOUP

Meteorites falling on early Earth. Most scientists believe craters and undersea hydrothermal vents served as crucibles for the emergence of life

FAT BUBBLES

Bubbles of fat in geological environments would have enclosed proteins and genetic material called RNA to lead to single-cell organisms

Illustrations credit: Texas Tech University

Geologists call the period from the birth of the Earth about 4.5 billion years ago till about 4 billion years ago as the Hadean, an era during which meteorites and comets rained on a young planet, tearing open its crust and giving rise to volcanic activity and noxious gases.

“Comets delivered water and key ingredients of life from outer space, which were then accumulated, concentrated and polymerised in the crater basins on Earth created by the impacts,” Chatterjee said in his paper.

The icy comets that crashed melted and filled the crater basins with water and chemicals that would serve as the building blocks of life. As these basins filled up, he said, geothermal vents heated the water and created convection currents that would “churn and cook” the chemicals.

“Such convective activity could have segregated and concentrated organic molecules among the chemicals, allowing some to cluster over time into polymers, giving rise to proteins and primordial genetic material called RNA,” Chatterjee said.

He said pores and crevices in the craters could have served as “scaffolds” that would concentrate RNA and protein molecules. And membranous material delivered by the meteorites could have encapsulated the proteins and RNA.

“Once the membranes encapsulated these RNA and protein molecules, they would begin to interact and initiate the most basic processes of cells and lead to the emergence of other cellular components, including DNA,” said Chatterjee. “Replication would be the key breakthrough in the emergence of life.”

An Indian palaeontologist who is not associated with Chatterjee’s new research said it appeared to synthesise independent concepts that had been discussed earlier.

“There is evidence to support the idea that comets and meteorites delivered chemicals that served as building blocks of life,” said Guntupalli Prasad, professor of geology at the University of Delhi. “There is also evidence for the idea that life originated in hostile hydrothermal vents. His proposal combines both ideas towards a complete theory.”

In palaeontology circles, Chatterjee, who did his PhD from Calcutta University before pursuing postdoctoral studies in the US, is best known for his work on how birds evolved from a class of dinosaurs.

He has also proposed that a giant rock from space had crashed off the coast of present-day Mumbai and contributed to the demise of the dinosaurs about 65 million years ago. He has named that impact crater, located in the Arabian Sea, Shiva.

The quest for the origin of life, Chatterjee said, is like a “Holy Grail of science”. But, he said, it is a subject that has been “dominated by biologists and chemists, although it is so deeply connected to geology”.