Cultural diffusion is the spread of culture – both material and nonmaterial – and the methods that account for it, such as migration, communications, trade, and commerce. Because culture moves over space, the geography of culture is constantly changing. Cultural traits that originate in an area, known as the cultural hearth, spread outward, ultimately to characterize a larger expanse of territory. Culture region describes the location of culture traits or cultural communities; cultural diffusion helps explain how and why they got there.

For example, the Pacific Northwest lies within the English-speaking culture region. Nevertheless, there are significant cultural communities within the region in which Spanish, Chinese, Korean, Hindi, Arabic, or another language is dominant.  Similarly, while most of the Pacific Northwest is part of the Christian culture region, there also are local cultural communities in which Judaism, Islam, or Buddhism is dominant. What all these languages and religions have in common is that none originated in Pacific Northwest or even in North America.

Similar stories apply to other parts of the world; particularly those parts that were colonized. In Australia, for example, most of the present-day Australian people and their homeland bear the unmistakable imprint of European culture because of cultural diffusion.

5.5.1 Relocation Diffusion

Cultural diffusion occurs in different ways, either by expansion or relocation. As suggested by the examples above, migration plays an important role. When people move, they take their “cultural baggage” with them. This is known as relocation diffusion. There are uncountable instances, past and present, in which the arrival of migrants has resulted in the appearance of culture traits otherwise alien to a place. Also, entire cultural communities might get established in areas where they were not previously present. It is also possible that people of one area end up in the same area abroad. See the example below.

An important modern variation involves businesses that establish facilities or outlets in foreign lands. Thus, the appearance of KFC, Burger King, and Starbucks outside the U.S. is a form of cultural diffusion—and so too the appearance of sushi bars in America.

5.5.2 Expansion Diffusion

Expansion diffusion is at work when innovations -artifacts, sociofacts or ventifacts – spread to new places while staying strong in their original locations. One sub-type of expansion diffusion is known as contagious diffusion. It is based on people’s tendency to copy one another. Take, for example, a farmer  who,  looking over the fence, sees a neighboring farmer using a different agricultural technique that works, and adopts it. Similarly, people sometimes adopt a new cultural trait in response to contact with an advertisement, or by seeing something on TV, a movie, on the internet, or by interacting directly with people who display a particular cultural trait.

Stimulus diffusion is common when a specific part of the cultural element is rejected, but the underlying concept is embraced; such as McDonald’s in India. Hindus don’t eat beef because they believe cows are sacred, so McDonald’s replaces the beef patties with veggie burgers; in Korea the chain offers sticky rice.

Finally, there is hierarchical diffusion, the tendency for culture traits to originate and take hold first in large cities and then “trickle down” to smaller cities, towns, and rural areas. Contemporary cultural fads, like hip hop music or photo selfies, in particular, tend to diffuse in this manner. Because diffusion occurs over time as well as over space, there may be a time lag between the origin of a trait in a large city and its appearance in small towns and rural areas.

Nowadays, the above phenomenon is particularly evident and important in lower-income countries  where modernization tends to take hold in major cities and then trickle down to the countryside. China, for example, is a land of rapidly modernizing cities— there are many with world-class industries, office towers, and port facilities. However, portions of rural China are still dominated by traditional pre-modern agricultural tools and techniques. Therefore, China is not a cultural community but is instead a mosaic of many cultural communities. The same is true of Mexico, India, Peru, and virtually every other country on Earth today. Cultural differences exist within countries as well as between them.

5.5.3  Barriers to Diffusion

It is important to understand that every “cultural community” is actually composed of numerous cultural communities which have their own characteristics and traditions. When a cultural element diffuses, it typically does not keep spreading and spreading forever. Instead, it tends to diffuse outward from its place of origin, encounters one or more barrier effects—things that inhibit cultural diffusion—and then stops spreading.

Barrier effects can assume physical or social forms. Physical barrier effects consist of characteristics of the natural (physical) environment that inhibit the spread of culture. The classic examples are oceans, deserts, mountain ranges, dense forests, and frigid climates. For example, the Atlantic Ocean was a physical barrier that prevented the westward spread of European culture for many centuries. The dense rain forest of the Amazon lowlands long served as a physical barrier, isolating numerous native peoples and their ancient ways of life. While some of these groups have recently experienced culture change wrought by roads and deforestation, others continue to lead traditional lives in remote regions of the rainforest. Similarly, the rugged Andes Mountains have long served to inhibit diffusion of foreign culture throughout that region, thus helping to perpetuate indigenous cultural characteristics. One result is that Quechua (pronounced KAY-chew-ah), purportedly the language of the Incas, continues to be spoken by millions of Andean residents.

Social barrier effects consist of characteristics that differentiate human groups and potentially limit interaction between them, thus inhibiting the spread of culture. Examples include language, religion, race and ethnicity, and a history of conflict between specific cultural communities. Islam, for instance, nowadays acts as a social barrier in many Middle Eastern countries by discouraging adoption of certain styles of western dress and music.

Barrier effects can also be studied by examining folk and popular culture. For example, the Amish continue to hold on to a flourishing folk culture amidst a larger, very different culture (Figures 5.10 and 5.11) The Amish live simple lives, rejecting modern technology and values. While they allow their young ones to explore the world on their own, many of those return to their roots. This social barrier preserves their culture by excluding as much of the outside world as possible. Even when the o

utside world imposes on their culture, usually because of economic pressures, the Amish resist assimilation into mainstream American culture by relying on their deeply ingrained sense of community, Gemeinschaft, which puts the needs of the community before the needs of individuals.