About 20 years ago my dad was doing research (at the U of Georgia) that traced how a peptide was metabolized by grasshoppers. They used an isotope of carbon wit

About 20 years ago my dad was doing research (at the U of Georgia) that traced how a peptide was metabolized by grasshoppers. They used an isotope of carbon with a 20 minute half-life (C11), but also needed to ensure that the radiation from Carbon-14 and other isotopes was very, very low. Essentially they needed grasshoppers with stable versions of carbon, which you're not going to get from the wild. So they grew plants and grasshoppers in a sealed environment, with CO2 (and probably other carbon sources) from oil. Since the hydrocarbons in the oil are millions of years old, the carbon is essentially exhausted of radioactive isotopes. If you carbon dated one of those grasshoppers it would have seemed tens of thousands of years old...