Answer:
Evidence of fossil apes and hominids in both East and West of the great rift valley
Explanation:
The East Side Story hypothesis opined that a tectonic plate movement created a seismic split in the earth, thus deepened the rift valley and created a geographical barrier between the east and the west of the great rift valley. The barrier created a kind of geographical isolation between the ancestors of hominids, dividing them into two with each population taking different evolutionary paths.
Thereafter, the ancestors in the western side of the rift valley evolved into the chimpanzee's family while those in the eastern side ultimately evolved into humans.
Thus, providing the fossils of apes and that of hominids in both East and West sides of the great rift valley will render the hypothesis invalid.
