Dying carbon stars may be source of our DNA

You’ve heard it before — all the carbon atoms in our bodies were created in the stars. Recently, a series of lab experiments have concluded that the chemical cosmic spheres surrounding dying carbon stars might have once successfully traveled through space, through Earth’s atmosphere to impact its surfaces. Scientists and researchers are on a mission to prove that the matter surrounding these carbon-rich dying stars could have potentially created bio-relevant, nitrogen-rich molecules.


The evolution of life, (partially) aided by dying carbon stars

The team behind this hypothesis simulated conditions in the circumstellar envelopes of these stars, and deduced that they would have the capacity for such a biochemical creation. First, they injected a gas made from a type of nitrogen-filled, single-ringed carbon molecule and two acetylene carbon-hydrogen molecules into a hot nozzle measuring 700 degrees Kelvin. Afterward, they probed the gas with radiation from the Advanced Light Source (ALS), registered as one of the world’s brightest sources of ultraviolet beams. The result? The initial gas transformed into the nitrogen-containing complex ring molecules of quinoline and isoquinoline.

With this result, the scientists are now judging that the very key molecules responsible for human existence can in fact be produced in the violently hot, stellar environments of dying carbon stars. They further surmised that these molecules would then be emitted into the interstellar medium (ISM) and, subsequently, be diffused by stellar winds.

The real question remains: how were these molecules that once surrounded dying carbon stars able to survive journeying through space to reach Earth’s surface?


How bio-relevant matter survives impact on Earth

After molecular clouds collapse and are transported to regions where stars are formed, the bio-relevant matter (that these dying carbon stars would eventually hold) have the ability to be incorporated into circumstellar disks, in which planetary bodies are also formed.

The main idea is that organics (including nucleic acids), which begin life in interstellar environments, can enter into “meteoritic parent bodies.” Therefore, upon impact on Earth, a certain portion of the organics that are shaped within the interstellar medium would have been able to survive.

Still, you might think: weren’t some prebiotic cell components, like RNA, molded by ocean sediments with sulfur-filled clay compounds (thioesters)? However, the truth is, glycerol — the basest unit of all prebiotic cell components — can only be shaped within a narrow frame of environmental conditions. It can’t be made at extreme pH degrees, or alongside calcium or magnesium salts, which existed in very small concentrations on Earth at the time.