The study presents new evidence that the Kibish Formation in southern Ethiopia contains hominid fossils from similar stratigraphic levels, despite differences in their morphology. Using $ ^{40}Ar/^{39}Ar $ dating on pumice clasts, the researchers determined that the hominid fossils are between 195.8 ± 1.6 kyr and 103.7 ± 0.9 kyr old. These ages are closely correlated with the ages of Mediterranean sapropels, which reflect changes in the Nile and Omo River flows. The results indicate that the hominid fossils are approximately 195 ± 5 kyr old, making them the earliest well-dated anatomically modern humans yet described. The study also highlights the importance of rapid deposition in the Kibish Formation and the significance of the correlation between the ages of the hominid fossils and the sapropels. The findings support the original report that Omo I and Omo II are derived from comparable stratigraphic levels within Member I of the Kibish Formation. The study provides a detailed analysis of the geological and stratigraphic context of the Kibish Formation, including the age and depositional history of each member. The results have important implications for understanding the tempo and mode of modern human origins.The study presents new evidence that the Kibish Formation in southern Ethiopia contains hominid fossils from similar stratigraphic levels, despite differences in their morphology. Using $ ^{40}Ar/^{39}Ar $ dating on pumice clasts, the researchers determined that the hominid fossils are between 195.8 ± 1.6 kyr and 103.7 ± 0.9 kyr old. These ages are closely correlated with the ages of Mediterranean sapropels, which reflect changes in the Nile and Omo River flows. The results indicate that the hominid fossils are approximately 195 ± 5 kyr old, making them the earliest well-dated anatomically modern humans yet described. The study also highlights the importance of rapid deposition in the Kibish Formation and the significance of the correlation between the ages of the hominid fossils and the sapropels. The findings support the original report that Omo I and Omo II are derived from comparable stratigraphic levels within Member I of the Kibish Formation. The study provides a detailed analysis of the geological and stratigraphic context of the Kibish Formation, including the age and depositional history of each member. The results have important implications for understanding the tempo and mode of modern human origins.