Final answer:
Heavy wear on the incisors and canines of early archaic Homo sapiens and Neandertal specimens in Atapuerca 5 suggests they used their front teeth for gripping materials, consistent with patterns observed in other Neanderthal remains.
Step-by-step explanation:
In Atapuerca 5, early archaic Homo sapiens and Neandertal specimens show heavy wear on the incisors and canines, indicating the use of the front teeth for gripping materials. This wear pattern is consistent with evidence of chipping and pitting on the incisors believed to have been caused by chewing on leather, as postulated for Neanderthal remains. Moreover, the shift in the Acheulean tool industry towards more complex toolmaking, including the use of materials such as antler, ivory, and bone during the Upper Paleolithic, suggests that the front teeth were not primarily used for shaping the cutting edges of stone blades. These stone blades required much more delicate crafting than what could be accomplished with teeth. The overall evidence does not support the idea of purposeful modification of teeth to demonstrate social rank like the Aztec practice, or the chewing of massive amounts of fibrous materials based solely on tooth wear.