The effect of UV radiation on solutions of free and clay-adsorbed DNA has been investigated. It turns out that clay (montmorillonite/kaolinite) adsorbed nucleic acid undergoes less radiation damage than free nucleic acid. Our laboratory experiments have an astronomical counterpart in terms of solar irradiance on the Earth. An origin of life scenario is proposed where ubiquitous clay minerals lead the surface chemistry of the molecules relevant to the biological evolution and at the same time protect them from the deadly rainfall of UV photons.
