Fig. 3: Comparison of CHB record and identified eastern African environmental episodes with key milestones and transitions in modern human origins.

a, CHB climate record (aridity proxy K/Zr) and 13 episodes of inferred habitat transformation (Fig. 2); b, Wet phases in CHB that align with wet pulses in northwestern Africa²⁴, and the Mediterranean²⁶ (Supplementary Fig. 3) as potential time windows for favourable migration routes out of Africa; AWP, aligned wet phases c, Innovation, comprising social, technological, symbolic and cultural evolution; evolution and expansion of cultural capacities (EECC) model⁴¹ with stage 6 comprising technological augmentations, stage 7 with complementary cultural capacity, for example, bow and arrow, and stage 8 with notional cultural capacity, for example, notional concepts and beliefs (see Supplementary Note 4 for detailed information); long-distance raw-material transport, indicative of formation of social networks⁴². d, Key archaeological finds discussed in the text: earliest MSA occurrence in Ethiopia at Gademotta²⁹ and in Kenya at Olorgesailie³ and early symbolic artefacts at Porc-Epic⁴⁹, Goda Buticha⁵⁰. e, Behavioural transitions: Acheulean–MSA transition³¹; MSA–Later Stone Age (LSA) transition⁴⁶. f, Key H. sapiens fossil finds in eastern Africa and the Levant/Saudi Arabia as discussed in the text; g, Simplified key phases of modern human origin adapted from ref. ¹¹.