about 7MYA- Chimpanzees, gorillas, & humans diverge from a common ancestor. Gorillas will further split into eastern & western species, & the easterns will split into lowland & mountain subspecies. By the 21st century CE, there will be fewer than 3800 eastern lowland gorillas. One of their last refuges will be the Kahuzi-Biéga National Park in the Democratic Republic of the Congo.