Final answer:
The Acheulean complex originated around 1.6 million years ago and signifies a more advanced stone tool technology associated with Homo ergaster, featuring biface hand axes made using the soft hammer technique.
Step-by-step explanation:
The Acheulean complex, known for its more sophisticated tool production, emerged around 1.6 million years ago and was primarily associated with Homo ergaster. Acheulean tools are distinguished from the simpler Oldowan tools by their biface design, where a tool is worked on both sides to create a symmetrical shape. These Acheulean hand axes required greater cognitive ability and motor skills to produce and served as versatile tools for cutting, scraping, and chopping. Acheulean tools were typically created using the soft hammer technique, where softer materials like wood or bone were used to shape harder stones such as flint.