The earliest Buckeye Knoll individuals — those dating to around 8,500 years ago — showed elevated isotope values consistent with significant consumption of aquatic resources, likely freshwater fish and shellfish from the Guadalupe River and possibly marine resources from the nearby coast.

Later populations at the same site showed a shift toward more terrestrial resources.

This temporal shift in diet mirrors what is known from other lines of evidence about changing environmental conditions in southern Texas during the Archaic period.

As the post-glacial climate continued its transition toward modern conditions, the productivity of the river systems may have changed.

Populations that had relied heavily on aquatic resources were adapting their strategies.

The strontium isotope analysis of tooth enamel — a technique that can indicate where an individual spent their childhood, because the strontium signature of enamel reflects the local geology of the food and water consumed during tooth formation — has the potential to reveal patterns of mobility and migration in ancient populations.