Thus, compare us with those we learn from and you will find more similarities than differences. However, if you compare groups of people rather than the individuals within a group, cultural differences become much more apparent. Anthropologists try to explain how these differences develop and why they exist. When many different and diverse cultures were compared, it was found that they could be grouped into a progression based on complexity. This progression formed the basis for the concept of cultural evolution .
Evolution is the simply the process of stepwise change.
Something evolves by building off of what preceded it. Since the 1950's cultural evolution refers to the non-directed change in complexity of cultures through time, where complexity can be measured by several categories, but we will only consider energy use. Cultures that are more complex use more energy than those that are less complex. A stable culture is one that is best adapted to the balance of energy needs vs. energy availability. If a culture becomes so complex that it needs more energy than it can obtain, it will simplify itself to a level that uses less energy.