Fig. 3: LOESS regression trends in the mean and standard deviation of the trait values of eastern African large herbivores.

Trends show temporal changes in herbivore body mass (a, b), hypsodonty (c, d), and longitudinal loph count (e, f). Each data point represents a 250,000-year time bin. Body mass is measured in log-transformed kg, hypsodonty on a discrete scale of 1–3 (1 = brachydont, 2 = mesodont, 3 = hypsodont), and loph count as a count from 0 to 2. Each data point is presented as a mean value ± one standard error from n = 1000 independent samples of species (see Methods). LOESS regression curves use a smoothing parameter of 0.75. Faded gray bars denote breakpoints from breakpoint analysis. Blue-shaded areas refer to events related to environmental change and orange to events in hominin evolution. These events are encompassed in key time intervals, as follows: 7.5–5 Ma includes the onset of grassland expansion and the emergence of hominins (7 Ma); 3.3–3 Ma includes the mid-Pliocene Warm Period and the development of Oldowan hominin tools (3 Ma); 1.9–1.7 Ma includes the increase in climate variability and aridity, as well as the emergence of Homo erectus (1.9 Ma) and their development of Acheulean technology (1.7 Ma); and ≤1 Ma includes the intensification of periods of aridity, as well as rapid cranial growth in hominins (1 Ma). Source data are provided as a Source Data file.