The two human species had many similarities but their communication would have been different.
Callao Cave on Luzon Island in The Philippines, where the fossils of Homo luzonensis were discovered.
Callao Cave Archaeology Project (Florent Détroit)
Reports say that a new species of ancient human has been identified in a cave in The Philippines. But only a few bone and teeth fossil fragments have been found, so far.
An Oldowan core freshly excavated at Ain Boucherit from which sharp-edged cutting flakes were removed.
M. Sahnouni
The big question being asked is: where does Homo naledi fit in the evolutionary tree? Assessing the similarity or dissimilarity between fossil skulls has provided a possible clue to the answer.