Our second lecture on evidence for evolution will concentrate on fossils. That is , carbon decays into nitrogen, an electron, and an electron antineutrino. Absolute dating is used to determine a precise age of a fossil by using radiometric dating to measure the decay of isotopes, either within the fossil or more often. Potassium-argon dating, Argon-argon dating, Carbon (or Radiocarbon), Since genetic material (like DNA) decays rapidly, the molecular clock method can 't date very old fossils. Chart of human evolution milestones and dating methods. time, the evidence for events in Earth's history, relative and absolute dating.