 Integration and differentiation represent two different stages in the evolution of a system. Differentiation is the process whereby an integrated system becomes divided up into more specialized, well-defined parts. Integration is the process whereby diverse elements become combined or synthesized into a whole system. The process of evolution involves a dynamic interplay between systems differentiation where new different elements are created and systems integration where these elements that are best suited to the whole system are selected by the environment as the system becomes reintegrated. Differentiation means the process of becoming or making something different. Differentiation involves a process of disintegration, the dividing up of an integrated system into more specialized subsystems. Through the process of differentiation, what was originally a homogeneous system becomes heterogeneous as its constituent subsystems come to form their own identity and structural features that are distinct from each other. Differentiation enables specialization. The formation of separate individual subsystems enables those components to focus more intensely on a particular function or activity, thus allowing them to become more specialized in their activity than if they had to perform a large number of diverse activities. Systems differentiation is likewise a structural technique for solving the temporal problems of a system situated in a complex environment. Systems differentiation is understood in systems theory as a way of responding to and dealing with the complexity of the systems environment. This is accomplished through the creation of subsystems in an effort to copy within the system the difference between it and the environment. In this context, the differentiation process is a means of increasing the complexity of the system since each subsystem can make different connections with other subsystems. It allows for more variation within the system to respond to variation within its environment. The development of modern societies into many different specialized institutions from what were largely homogeneous organizations within pre-modern societies is an often cited example of differentiation. One of the central ideas of the systems sociologist Nicholas Luhmann was that modern society is differentiated into various self-referential functional subsystems which operate according to their own particular logic without being subordinate to a central unit. They are open for exchange with each other but also independent, being largely responsible for their own functioning and development. Biological differentiation is the process by which cells or parts of an organism change during development to serve a particular function. For example, the cells of an animal in its early embryonic phase are identical at first but develop through differentiation into specialized tissues such as bones, heart, muscle and skin. Differentiation within a material is any process in which a mixture of materials separates out partially or completely into its constituent parts, as in the cooling and solidification of a magma into two or more different rock types, or in the gradual separation of the original homogeneous earth into crust, mantle and core. Likewise, within economics, product differentiation is a marketing process that showcases the difference between products. Differentiation looks to make a product more attractive contrasting its unique qualities with other competing products. Systems integration involves the interrelating and recombining of differentiated parts. Systems integration is the composition of a whole functioning system by assembling elements in a way that allows them to work together to achieve an intended purpose. In engineering, for example, systems integration is defined as the process of bringing together the component subsystems into one system and ensuring that the subsystems function together as a whole system. This integration requires the development of new layers of abstraction that can accommodate the diversity of the differentiated components it is designed to interrelate. Integration involves the development of a generic layer to integrate the differentiated elements. For example, to enable the development of a new level of socioeconomic organization in the formation of globalization, it is required that we develop some language through which the different societies can interoperate. This integration process through which a new, more abstract level of organization combines the elements also works to reduce their autonomy in order to align them within the functioning of the whole system. For example, the formation of the political entity of the European Union enables interoperability between the different countries but likewise constrains their national governments. In a paper entitled A Complexity Drain on Cells in the Evolution of Multicellularity, Daniel McShee describes this process in living organisms as such. In evolution, as high level entities arise from associations of lower level organisms and as these higher level entities acquire the ability to feed, reproduce, defend themselves and so on, the lower level organisms will tend to lose much of their internal complexity. Integration both constrains and enables differentiation. Cells in a multicellular organism can rely on the whole organism adapting to changing conditions via a multicellular response. Thus the individual cell can do away with its rarely used functions to become more specialized and differentiated within the whole organism. And social insects demonstrate the same sort of trade-off. Individuals of a highly social ant species are less complex than individuals from socially simpler ant species but it is the complex social interaction or integration between them that allows them to perform as a whole more efficiently. Differentiation and integration enable and create each other. Integration can only take place when there are different parts. Likewise differentiation can only occur through integration into a larger organization because elements that remain autonomous are required to perform multiple functions to maintain themselves within their environments. Differentiation thus actually becomes the basis for any form of unity since the unity of any subsystem can only be based on its difference from its environment. A central part of an evolutionary process of development is a dialectic interplay between a systems macro level that is integration into the whole and the micro level the differentiation of the parts. This process of development can be understood as a form of dialectic change. It is the dynamic interaction between the process of integration and differentiation that drives the evolutionary process of development within the system in a dialectic form. Homogeneous systems divide, define their difference, compete and then reintegrate into a more complex whole.