12C/13C Isotope Ratio


12C/13C Isotope Ratio: Due to their different photosynthetic pathways, C3 and C4 plants have different ratios of 12C and 13C isotopes in their tissues. This ratio difference allows researchers to derive diet information from the fossilized tissue of animals, including human ancestors. Isotope ratios indicative of C3 plants suggest browsing from foliage while C4 isotope ratios suggest grazing.

Please note: this information does not differentiate between a diet of eating C3 and C4 plants, eating the meat of an animal that consumed those plants, or a combination of the two.