Human ecology and comparing ecosystems

Human ecology studies the links between human communities and their surroundings, and how environmental factors affect health. Like other organisms, humans depend on environmental factors, yet they change the environment deliberately, use powerful energy sources and build an artificial environment. Health is affected by physical (noise, temperature, radiation), chemical (toxic substances in air and water), biological (microbes, parasites) and social (housing, work and rest routine, nutrition) factors. Groups living in different climates have developed adaptations: heat production is strong in cold regions, sweating is active in hot, humid ones, and in mountains the blood carries many red cells and much haemoglobin for oxygen transport. Such adapted groups are called adaptive types, and they depend on the living environment, not on race traits. In cities dense populations make infections spread more easily and air pollution and little movement are risks; in villages, diseases from animals and pesticides are more of a risk.