Final answer:
Stone tool use, vocal communication, and care for others suggest that Homo erectus had advanced intelligence compared to other species.
Step-by-step explanation:
One of the abilities unique to Homo erectus of the early Pleistocene that suggests advanced intelligence is the use of stone tools. Homo erectus made and used sophisticated stone tools, showing their ability to think critically and problem solve. Additionally, evidence suggests that Homo erectus may have had some capacity for vocal communication, aiding in cooperative endeavors. Lastly, the discovery of Homo erectus caring for the sick and elderly indicates a level of empathy and social intelligence.