That half-life is critical to radiocarbon dating. Since carbon-12 doesnt decay, its a good benchmark against which to measure carbon-14s inevitable demise. The less radioactivity a carbon-14 isotope emits, the older it is.

Does more carbon-14 mean older or younger?

Carbon dating only works for objects that are younger than about 50,000 years, and most rocks of interest are older than that. Carbon-14 has a half life of 5730 years, meaning that 5730 years after an organism dies, half of its carbon-14 atoms have decayed to nitrogen atoms.

Why is carbon-14 limited when dating objects that are very old?

Carbon-14 is a radioactive isotope of carbon. Its has a half-life of about 5,730 years. The short half-life of carbon-14 means its cannot be used to date extremely old fossils.

How much carbon-14 is in a human?

Using a half-life of 5,730 y, one obtains a specific activity of 0.19 Bq g-1 of carbon. As carbon is 23 percent of the body weight, the body content of 14C for a 70-kg person would be about 3.08 kBq.