There are many ways in which the environment impacts human health and behavior. The environment provides resources like food, water, air, fuel and minerals that are necessary for human life. However, factors in the environment can also negatively impact human health by increasing exposure to diseases, pollution, and extreme weather events. Changes in climate conditions may enhance the spread of diseases by affecting food, water, and animal transmitters. The environment also influences human stress levels, lifestyles, and skin color variations that developed as adaptations to local sun exposure levels.