To study the change in diet as human populations changed lifestyles from hunter-gatherers to agriculturalists, scientists measured carbon isotopes in the collagen tissues of human skeletons from North America.
Carbon isotope ratio data in bone collagen from human skeletons found in Illinois, Ohio, and West Virginia, dated 4,000 B.C. to 1,500 A.D. The number and sex of the individuals found at each location are indicated in parentheses.
Download the educator guide PDF, which includes questions to guide a class discussion on the graph characteristics and what the data show.
Figure 6 from: van der Merwe NJ. Carbon Isotopes, Photosynthesis, and Archaeology: Different pathways of photosynthesis cause characteristic changes in carbon isotope ratios that make possible the study of prehistoric human diets. American Scientist 1982; 70(6):596–606.