Question

The following passage explores the scientific origin of homochirality in biological molecules.

For decades, the homochirality of biological molecules—the fact that all living organisms use exclusively left-handed amino acids and right-handed sugars—was considered an insolvable biological mystery, often attributed to mere evolutionary chance. However, contemporary astrobiological research has shifted this paradigm by locating the origins of homochirality in interstellar space.

The foundation of this theory rests on the detection of enantiomeric excesses in carbonaceous meteorites, such as the Murchison meteorite. Organic compounds within these meteorites exhibit a slight excess of left-handed amino acids, suggesting that a bias was established prior to the emergence of life on Earth. Researchers hypothesize that this initial asymmetry was induced by circular polarized light (CPL) from nearby neutron stars in the presolar nebula, which selectively destroyed right-handed molecular precursors.

As these meteorites bombarded the early Earth during the Late Heavy Bombardment, they delivered this prebiotic organic material to the planet's surface. In terrestrial environments, particularly within hydrothermal vents or shallow pools, mineral catalysts like quartz or clays selectively adsorbed these molecules, amplifying the initial microscopic imbalance. Through these autocatalytic chemical networks, the slight asymmetry was driven to completion, culminating in the exclusive homochirality observed in the first self-replicating protocells.

Thus, the molecular preference of terrestrial life is not an arbitrary product of early Earth chemistry, but a legacy of cosmic radiation that shaped prebiotic matter long before Earth itself coalesced.

Based on the passage, in what order does the author develop the central argument that biological homochirality originated in cosmic space rather than on Earth?