Final answer:
During the time of Homo erectus, there was a significant advancement in tool technology, transitioning from simple Oldowan tools to the more complex Acheulean tools with the development of hand axes.
Step-by-step explanation:
The period associated with Homo erectus represents a significant phase in prehistoric technological development. Homo erectus is renowned for their use of the Acheulean tool industry, which marks a notable advancement from the simpler Oldowan tools. Acheulean tools, including bifaces such as hand axes, appear approximately 1.6 million years ago and demonstrate a skilled level of craftsmanship and an understanding of symmetrical design.
Homo erectus' invention of biface tools reflects their capability for abstract thought and planning, which are critical elements in the evolution of human intelligence. Their technological innovations are linked with various anatomical changes and an increasing reliance on a meat-based diet, which is thought to have been fueled by larger brain sizes, a finding supported by the “expensive tissue hypothesis”.
Key evolutionary changes during the reign of Homo erectus included the introduction of new tools and potential protolanguage to communicate complex ideas necessary for teaching tool construction. As such, the tools and the implied cognitive abilities of Homo erectus have been critical in understanding early human development, greatly impacting subsistence patterns and cultural expressions.