Figure 1.

Correlated changes in $\delta$¹⁸O from tooth enamel (top) and $\delta$¹³C from bone collagen (middle) reflect minimal environmental changes across archaeological layers at La Ferrassie. Summer (yellow), mean annual (green) and winter (blue) $\delta$¹⁸O values are shown as individual points with a line connecting the layer means and a ribbon visualizing the maximal spread of the data. Summer peak and winter trough values are derived from sinusoidal $\delta$¹⁸O curves and are shown in Supplementary Figure S8. Mean annual points represent the average of peak and trough values, analogous to the calculation of modern mean annual temperatures. Summer temperatures and mean annual conditions stay stable between Layer 2 and 5. Winter temperatures show small differences between Layer 2 and Layers 5A and 5B, and are lowest and most variable in Layer 2. Diachronic in $\delta$¹³C and $\delta$¹⁵N values are congruent with small changes in winter $\delta$¹⁸O and support that each system robustly reflects an overall picture of relatively homogeneous temperature, soil isotope values and/or plant community structure with only subtle changes between layers.