All forms of life require energy to function. Prior to humans entering the scene, sunlight was responsible for all energy creation. Plants have evolved to convert the primary energy contained in sunlight into the chemical energy required for growth and life. Many animals have evolved to harness the chemical energy contained in plants. Higher-order animals evolved to consume the animals that eat plants. When any of these organisms dies, it turns back into nutrients that can be used to fulfill the energy needs of future generations of organisms.
Other primary forms of energy are also dependent on the sun. Wind is created by uneven heating of the earth by the sun, generating thermal imbalances that cause air movement as the atmosphere seeks to reach equilibrium. Waves are kicked up by the wind that is created by the temperature imbalances. Only the tides are not dependent on the sun, but rather the gravitational pull of the moon orbiting the Earth.
The unique thing about humans is that we’ve learned to harness vast amounts of energy that aren’t accessible to any other organism. Only humans have learned to burn wood and fossil fuels and control nuclear reactions.
This ability is our great evolutionary strength as a species. It enables us to produce much more than we could if we were dependent on plants and animals for all of our energy. It also means that we are utterly dependent at this time on the ability to harness primary energy sources that are unavailable to other organisms.
We’ll get into this historical perspective on energy a bit more in the next section. For now, just keep in mind that our entire civilization is dependent on the global energy economy.
Images: “Leaves and Sunny Skies” by iStock