Isotope results from the Middle Neolithic reveal that sheep were likely grazing on the shore and that humans relied on a diet ...

A potential problem is that nitrogen is a building block of proteins and therefore may succumb to protein catabolism occurring during migration, which can cause increased nitrogen isotope ...

and the sum of the protons and neutrons gives the atomic mass, the number of neutrons defines the isotope of that element. For example, most carbon (≈ 99 %) has 6 protons and 6 neutrons and is written ...