ANTH 3512 Lecture 2: Reconstructing Paleoenvironments and the Pilo-Pleistocene Climate
Document Summary
Climate: climate drives species evolution (sometimes) The issue of scale: environmental changes in global scale vs. where humans are. Relies on the differential weight of 16o and 18o. Water molecules comprised of light oxygen (16o) evaporate more readily. In warm climates: 16o is trapped in glacial ice, ration of 16o and 18o is seawater constant. In cold climates: 16o is trapped in glacial ice, seawater becomes depleted in 16o. Continual cooling trend beginning around 3. 5 mya. Multiple glacial periods from 2. 5 mya, increasing in the last 1. Increased aridity transports dust to ocean floor: amount, particle size. Formation of east african rift system increased ephemeral lake. Important info on wet and dry cycles on the regional scale formation. Indicates increased patterns of very wet very dry climate variability. Colder and wetter environments= dominated by trees and shrubs: c3 photosynthetic pathway: lower 13 c values. Warmer and more arid environments = dominated by grass: c4 photosynthetic pathway: higher 13 c values.
