Advantages of early farming.
- Humans could settle down and develop their culture (trading).
- More food available.
- Humans could live in environments with low food supply.
Slash and burn method.
- Burning trees leaving behind ash which is rich in nutrients.
- Yield falls with subsequent crops.
- Crops are harvested before they die/decompose.
- Nitrogen is not recycled and does not return to soil.
- Soil becomes less fertile - farmers move away after a few years.
Evidence for farmed animals
- Age of death (predominately adult sized bones) - hunters kill animals of extreme ages e.g. very old and very young. Those more vulnerable are easier to hunt.
- Bone structure - different to wild animals due to selective breeding.
- Pollen analysis - same type of pollen in farmed areas.
Selective breeding - the intentional breeding of organisms with desirable traits in an attempt to produce offsping with similar desirable charateristics or with improved traits.
- Cereals - wild grasses loose seeds before they can be harvested. Stronger grasses retain seeds and can be sown next year, selectively taken grains from cereal grasses that produce a high yield. Other grains are eaten, tall stalks allows hand picking, strong stalks prevent lodging (wheat damage by strong wind). Short stalks; prevent lodging, better for harvesting by machinery and energy from sunlight used to produce better grain rather than long stalk.
- Dogs - barking dogs frightened predators (wild adult dogs don't bark as much). Wild dogs that attacked children were killed, selected to assist rounding up sheep and cattle.
- Cattle - used because they ate grass which couldn't be used by humans, stay in herds so were easier to control. Dairy cattle produced high volumes of milk, beef cattle had larger amounts of muscle.
Succession - process by which different species make up a community over time.
1) Seeds are blown by wind, so that grasses and small herbaceous plants start to grow on the bare earth.
2) After a while small woody plants and young trees start to appear, forming shrub. These plants grow taller than the grasses and herbaceous plants, and compete with them for sunlight.
3) This means the smaller plants start to die out, young trees start to grow even taller after a while.
4) They complete with shrubs and smaller plants for light, eventually the land is covered with forest.
Climax community - a stable community of plants and animals that will remain unchanged unless the environment changes. Results from the process of succession.
Biodiversity - range of organisms living in a particular area.