Answer: 1. Being able to carbon date fossils
From the daily exposure to radioisotopes of organisms, scientists discovered to carbon date fossils. In carbon dating, the age of organic matter can be determined from the relative proportions of C-12 and C-14 i.e. isotopes of Carbon (carbon 12 and carbon 14). This ratio changes over the years because carbon-14 decays and is not replenished as there is no exchange with the atmosphere.