Đang chuẩn bị liên kết để tải về tài liệu:
design of machine elements
Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
The discovery and utilization of fire, a simple energy source with many profound uses, was a turning point in the technological evolution of humankind.[26] The exact date of its discovery is not known; evidence of burnt animal bones at the Cradle of Humankind suggests that the domestication of fire occurred before 1,000,000 BC;[27] scholarly consensus indicates that Homo erectus had controlled fire by between 500,000 BC and 400,000 BC.[28][29] Fire, fueled with wood and charcoal, allowed early humans to cook their food to increase its digestibility, improving its nutrient value and broadening the number of foods that could be eaten.[30].