how life began
Indian
American geoscientist Sankar Chatterjee recounts his journey from
explaining extinction to chronicling genesis and how it feels like to
belong to Kolkata's first family of pioneers.
Once
a discoverer of lost dinosaurs, he is the world's first paleontologist
to find an answer to science's 'holy grail'--the origin of life. Indian
American geoscientist Sankar Chatterjee recounts his
journey from explaining extinction to chronicling genesis and how it
feels like to belong to Kolkata's first family of pioneers.
Tell us a bit about your theory.
A cell has three basic components--cell membrane, protein and nucleic acids. If we can postulate how these three components evolved in young Earth to become a replicating cell, we may tackle the question of the origin of life. Between 4.1 and 3.8 billion years ago, the earth was pounded daily by large meteororites. These rocks punched holes and craters in the crust and created geothermal vents. Comets full of ice brought with them water and life ingredients on earth. They had amino acids, sugar and phosphorus, fatty bubbles, and nucleotide bases. In other words, the critical building blocks of life were already synthesized in space. Earth was just the right distance from the sun for water to exist here in liquid form. This is the cosmic stage of origin of life. In the geological stage, hydrothermal vents on ocean floors became the crucible of life. Next came the important chemical stage, and lastly the biological stage.
What happened in the chemical and biological stages?
In the chemical stage, the analogy of a pressure cooker comes to mind during life formation, which was not powered by the sun, but by the heat and chemicals of volcanoes in the crater basins. It was hot and dark environments, full of obnoxious gases such as methane, hydrogen sulphide, carbon dioxide. The cell membranes were the first to be formed in the crater basins. These lipid membranes have been detected in meteorites and came to earth on space body.
The biomolecules were joined to form long chains or polymers. At this stage, constant convection current brought the lighter membranes to the bottom of the crater basins where they began to trap the polymers such as simple chains of RNA and proteins that originated simultaneously. The RNA protein molecules were enclosed by cell membrane to form a protective environment, which was an important prerequisite for interaction between two molecules. The dual origin of protein and RNA molecules helps to jumpstart symbiotic relationships to make more custom-made RNA and proteins within protocells. In millions of of trial-and-errors, simple chain of RNA molecules gave rise to complex ones, such as DNA.Communication between DNA, RNA and protein led to formation of the genetic code that helped the protocells to replicate. This is the biological stage. Replication is the key signature of life, when a protocell divides into two identical daughter cells. Without symbiotic relationship between RNA and proteins within a cell membrane, life could not have formed in early earth.
How long did you work on your theory? Was there a special 'Eureka moment'?
(Laughs) Come to think of it, I had just delivered a talk when I found certain aspects of it coming together. I was working on this problem for the last five years, but there were some gaps in the narrative. But I have been working on asteroids for about 20 years. Origin-of-life theories have mostly been the domain of chemists and biologists. But paleontologists--who know the environment of early earth and how the oldest organisms look like--were so far only onlookers to this debate.
Tell us about your research on dinosaurs. Have you identified many new species? What is Shuvosaurus, the dino named after your son, like?
My current research has revolved around how birds evolved from a group of theropod dinosaurs and how flight evolved. I have identified and named so many species, I have lost count. Many of them were found in India, Antarctica, China, and the American southwest. I named one dinosaur after my son Shuvo, who discovered Shuvosaurus. It is a small, bipedal, herbivorous dinosaur about the size of a modern-day ostrich that lived in Texas 225 million years ago. I also worked on the asteroid theory of extinction of dinosaurs. A huge impact crater is located in the Arabian Sea off Mumbai coast. I called it Shiva. It's the largest oilfield in India.
You come from a family of pathbreakers, your younger brother Gautam Chatterjee being a pioneering musician. Who has been the inspiration in your work and career?
I did encourage Gautam a lot; I was his elder brother. He adored me. When I returned home from London University, I got him his first professional-level guitar. After his death, I wrote a book, 'Jaisther Halud Dupur' which was dedicated to Gautam.
For inspiration, I would like to remember British paleontologist Pamela Robinson whom I met at Indian Statistical Institute, Kolkata, after I got my MSc from Jadavpur University. It was she who inspired me to take up paleontology. ISI's geology museum is incidentally the only museum in India where you can see dinosaurs. Most of the exhibits here have been collected by me and my colleagues. Paleontologists from all over the world come to study Indian dinosaurs at the ISI museum in Kolkata.
Tell us a bit about your theory.
A cell has three basic components--cell membrane, protein and nucleic acids. If we can postulate how these three components evolved in young Earth to become a replicating cell, we may tackle the question of the origin of life. Between 4.1 and 3.8 billion years ago, the earth was pounded daily by large meteororites. These rocks punched holes and craters in the crust and created geothermal vents. Comets full of ice brought with them water and life ingredients on earth. They had amino acids, sugar and phosphorus, fatty bubbles, and nucleotide bases. In other words, the critical building blocks of life were already synthesized in space. Earth was just the right distance from the sun for water to exist here in liquid form. This is the cosmic stage of origin of life. In the geological stage, hydrothermal vents on ocean floors became the crucible of life. Next came the important chemical stage, and lastly the biological stage.
What happened in the chemical and biological stages?
In the chemical stage, the analogy of a pressure cooker comes to mind during life formation, which was not powered by the sun, but by the heat and chemicals of volcanoes in the crater basins. It was hot and dark environments, full of obnoxious gases such as methane, hydrogen sulphide, carbon dioxide. The cell membranes were the first to be formed in the crater basins. These lipid membranes have been detected in meteorites and came to earth on space body.
The biomolecules were joined to form long chains or polymers. At this stage, constant convection current brought the lighter membranes to the bottom of the crater basins where they began to trap the polymers such as simple chains of RNA and proteins that originated simultaneously. The RNA protein molecules were enclosed by cell membrane to form a protective environment, which was an important prerequisite for interaction between two molecules. The dual origin of protein and RNA molecules helps to jumpstart symbiotic relationships to make more custom-made RNA and proteins within protocells. In millions of of trial-and-errors, simple chain of RNA molecules gave rise to complex ones, such as DNA.Communication between DNA, RNA and protein led to formation of the genetic code that helped the protocells to replicate. This is the biological stage. Replication is the key signature of life, when a protocell divides into two identical daughter cells. Without symbiotic relationship between RNA and proteins within a cell membrane, life could not have formed in early earth.
How long did you work on your theory? Was there a special 'Eureka moment'?
(Laughs) Come to think of it, I had just delivered a talk when I found certain aspects of it coming together. I was working on this problem for the last five years, but there were some gaps in the narrative. But I have been working on asteroids for about 20 years. Origin-of-life theories have mostly been the domain of chemists and biologists. But paleontologists--who know the environment of early earth and how the oldest organisms look like--were so far only onlookers to this debate.
Tell us about your research on dinosaurs. Have you identified many new species? What is Shuvosaurus, the dino named after your son, like?
My current research has revolved around how birds evolved from a group of theropod dinosaurs and how flight evolved. I have identified and named so many species, I have lost count. Many of them were found in India, Antarctica, China, and the American southwest. I named one dinosaur after my son Shuvo, who discovered Shuvosaurus. It is a small, bipedal, herbivorous dinosaur about the size of a modern-day ostrich that lived in Texas 225 million years ago. I also worked on the asteroid theory of extinction of dinosaurs. A huge impact crater is located in the Arabian Sea off Mumbai coast. I called it Shiva. It's the largest oilfield in India.
You come from a family of pathbreakers, your younger brother Gautam Chatterjee being a pioneering musician. Who has been the inspiration in your work and career?
I did encourage Gautam a lot; I was his elder brother. He adored me. When I returned home from London University, I got him his first professional-level guitar. After his death, I wrote a book, 'Jaisther Halud Dupur' which was dedicated to Gautam.
For inspiration, I would like to remember British paleontologist Pamela Robinson whom I met at Indian Statistical Institute, Kolkata, after I got my MSc from Jadavpur University. It was she who inspired me to take up paleontology. ISI's geology museum is incidentally the only museum in India where you can see dinosaurs. Most of the exhibits here have been collected by me and my colleagues. Paleontologists from all over the world come to study Indian dinosaurs at the ISI museum in Kolkata.
No comments:
Post a Comment