Final answer:
Brian advanced his food acquiring techniques primarily by learning to fish and using a bow and arrow, as indicated by the text detailing early human subsistence strategies and tool-making.
Step-by-step explanation:
Brian advances his food acquiring techniques by learning to fish and by using a bow and arrow. These methods are discussed in the text as part of the evolution of early human subsistence strategies. Early humans depended on a variety of food sources based on their environment, often utilizing fishing strategies including spears, nets, and hooks made of bone, and hunting with tools such as stone spearheads. As their tools and methods evolved, they began to focus more on specific aspects of food procurement and production, such as using more specialized weapons for hunting and tools for food preparations.
The text also mentions that an essential activity associated with food acquisition was the manufacture of weapons and tools for cutting meat and scraping animal skins, indicating an advancement from basic gathering to more sophisticated hunting techniques. These developments in tool-making and hunting strategies allowed early humans to improve their ability to acquire food efficiently.