carbon 13

Recent separate findings indicate that plant leaves receiving more light have a higher density of veins, as well as a higher ratio of a naturally occurring isotope called carbon 13.

So researchers compare the amount of carbon 14 with the levels of carbon 12 and carbon 13 to determine how much time has passed since an organism perished.

Carbon 13 usually comes from inorganic sources, such as volcanoes, while carbon 12 is tied to living things.

There’s carbon 12 and its ever-so-slightly-heavier sibling, carbon 13.

Back in the lab, geochemical analysis revealed low levels of carbon 13; photosynthesizing organisms had lived there, lots of them, he concluded.