1. decays
1. Radiocarbon dating depends on measuring the radioactive isotope of carbon known as carbon 14, which is ingested during a lifetime and steadily decays after death.
2. When plutonium decays it emits what is known as an alpha particle, a relatively big particle that carries a lot of energy.
3. They believe there could be a number of reasons behind the findings, including that the DNA of sperm decays over time.