The new way shows that all three could be close to being the first by using hydrogen sulfide.
Metabolism. In a cellular context, it means the chemical reactions that happen in cells that help keep it alive. These reactions are fairly complex, and for a long time we thought that they could only happen inside cells, which kind of leads to a chicken or the egg kind of paradox. Now, scientists have found that it is relatively simple to have metabolic reactions happen outside of cells.
RNA is used to make proteins. And you need these proteins to do things with RNA. But these experiments show that you don’t need RNA to get the metabolic reactions happening. They could have happened in the Earth’s early oceans.
By starting with what we think the Earth’s early oceans would have, along with the starting chemicals for metabolic reactions, then heating it to 50° to 70° C for 5 hours, they were able to produce 29 different metabolic reactions. These included glycolysis and the pentose phosphate pathway, which are needed for production of ATP.
This helps scientists understand abiogenesis, how life first started. It takes out the requirement for a cell to form with all of the necessary chemistry along with it out of whole cloth. The chemistry is capable of working before the first cell formed. The part we don’t understand yet is where the starting chemicals came from. We don’t know how they could have formed yet. But we’re getting closer.
When did life start? Here on Earth, about a billion years after the Earth formed. But that’s here on Earth. What about out in the universe somewhere? Well, Abraham Loeb has an interesting take on it. Right now, the Cosmic Microwave Background (CMB) is about 2.7 Kelvin. That’s 2.7 degrees above absolute zero. But it wasn’t always there. The CMB is leftover radiation from the Big Bang. As the universe expands, the energy gets spread out and the tempeature decreases, and now it’s just 2.7 Kelvin.
But, at some point in the past, it had to be around room temperature. Somewhere above the freezing point of water. That means that a rocky planet out in space, far from a star, would still be warm enough to support life.
These conditions existed when the universe was 15 million years old. That’s about 13 billion years ago.
OK. We don’t know that there was life then. But we know that the conditions could have been right for it.