The Buhl Woman’s carbon isotope values indicated a diet based primarily on terrestrial C3 plants and animal proteins — the kind of diet consistent with a late Pleistocene/early Holocene environment in which the plant foods available were cool-climate species rather than the tropical grasses that produce distinctive C4 isotope signatures.

This rules out substantial consumption of maize or other C4 crops, which were not present in the American West during the terminal Pleistocene anyway.

The nitrogen isotope values were high.

High nitrogen-15 values in bone collagen are produced by diets rich in animal protein, and they are especially elevated in people who eat large quantities of aquatic protein — fish, specifically.

The trophic enrichment of nitrogen-15 accumulates upward through food chains, so fish that are themselves eating other fish or invertebrates are especially nitrogen-enriched, and humans who eat those fish inherit that enrichment in their bone collagen.