Descriptive of groups. Asks How the group functions. Change is viewed as negative unless it helps the group to function better or is in response to an outside challenge. Tends to support the status quo. A functioning group is one that survives.
Analogies tend to be biological, see the group as an integral organism.
A theory that accounts for structural change through biological adaption to the environment. The theory was developed to account for diversity. All societies have structures and patterns that favor one roup over another. Therefore all societies have internal conflict between groups - those who benefit from the system and those who maintain it. Change is seen as positive and something that should be encouraged to change and improve the relationships between groups.