Natural selection and genetic modification study guide

The study of stone tools provides significant evidence for human evolution. Over millions of years, the sophistication and variety of stone tools increased, reflecting the developing cognitive abilities and technological skills of early hominins.

Initially, tools were simple pebbles with a few flakes removed to create a sharp edge. These early tools, such as Oldowan, were used for tasks like cutting meat from carcasses and breaking open bones for marrow. As hominins evolved, so did their tools. Acheulean handaxes, characteristic of Homo erectus, were more symmetrical and bifacial, indicating greater planning and dexterity. Later, Mousterian tools, associated with Neanderthals, involved more complex flaking techniques to produce diverse tools for specific tasks. The most advanced tools, attributed to early Homo sapiens, included blades, points, and composite tools, often made with specialized materials and methods.

Dating stone tools is crucial for understanding the timeline of human evolution. Since stone tools are durable and preserve well, they are often found in archaeological sites. Their age can be determined by dating the layers of rock or sediment in which they are found. Techniques like stratigraphy, which examines the relative positions of layers, and absolute dating methods, such as radiocarbon dating (for organic materials found alongside the tools, up to around 50,000 years old) or potassium-argon dating (for volcanic rock layers, suitable for much older sites), help establish a chronological framework for tool development. The context of the discovery, including associated animal bones or fossilised hominin remains, further informs our understanding of the toolmakers and their environment.

A growing human population continually increases the demand for food. Agricultural practices need to intensify and become more efficient to meet this demand. Two key solutions are the use of fertilisers and biological control. Fertilisers, containing essential mineral ions like nitrates, phosphates, and potassium, enhance crop yields by providing nutrients for plant growth. This directly boosts the amount of food produced per unit area. However, excessive use can lead to environmental issues such as eutrophication of water bodies, where algal blooms deplete oxygen and harm aquatic life. Biological control involves using natural predators, parasites, or pathogens to manage pests, reducing the need for chemical pesticides. This method is generally more environmentally friendly, as it avoids chemical pollution and reduces harm to non-target species. Its limitations include the potential for the control agent to become a pest itself if not carefully chosen, and it can be slower-acting and less predictable than chemical methods. Both strategies aim to increase food production but come with distinct benefits and environmental trade-offs.