Complex sentence: Some studies suggest that PAHs account for a significant percentage of all carbon in the universe, and PAHs are discussed as possible starting materials for abiologic syntheses of materials required by the earliest forms of life.
Split into simpler sentences: Some studies suggest that PAHs account for a significant percentage of all carbon in the universe. Polycyclic aromatic hydrocarbons are discussed as possible starting materials for abiologic syntheses of materials required by the earliest forms of life.