Final answer:
Allopatric speciation might have occurred due to the dispersal of H. erectus/ergaster populations throughout the Old World, resulting in geographic isolation and genetic divergence.
Step-by-step explanation:
Allopatric speciation might have occurred as a result of the dispersal of H. erectus/ergaster populations throughout the Old World. Allopatric speciation refers to the formation of new species due to geographic isolation. As the populations of H. erectus/ergaster migrated to different regions, they became separated by geographical barriers such as mountains, rivers, or deserts, which prevented gene flow between them. Over time, these isolated populations would have undergone genetic changes and accumulated enough differences to become reproductively isolated and thus give rise to new species.