Radiocarbon is used by archaeologists to date past cultures. All living things, ourselves included, are made partly from carbon, some of which is very slightly radioactive in keeping with the balance of the food chain. As plants and animals absorb nutrients and exude wastes, the radiocarbon is balanced in living things. When living things die, no more carbon, including radioactive carbon or carbon-14, is ingested. Instead, carbon-14 in the plant or animal begins to deteriorate at a fixed rate or half-life of 5500 years. This means that only half of the radioactive carbon remains after its half life. Radioactive carbon is measured using scintillation counting equipment which measures the emission of beta-particles. Nadlok wood and bone is only a few centuries old, so its radiocarbon is slightly different from living wood and bone, a difference that is measurable using advanced equipment.