In spite of the fact that invention occupied a dominant place in culture growth over such a long period of time, most of the content of modern cultures appears to have been gained through diffusion. The term diffusion refers to the borrowing of cultural elements from other societies in contrast to their independent invention within a host society.
In order for diffusion to operate on a substantial scale, there must be separate societies that have existed long enough to have elaborated distinctive ways of life. Moreover, those societies must be in contact with one another so that substantial borrowing is possible. These conditions probably developed late in the evolutionary process. Once begun, however, culture borrowing became so pervasive that most of the elements of most modern cultures, including our own, originated with other people.
Culture has grown, then, through a combination of invention and diffusion. It grew slowly at first, mostly as the result of invention. As the culture base expanded and societies became differentiated, the large -scale diffusion of traits become possible and the rate of growth speeded up. In modern times, and particularly in the Western world, the rate of culture growth has become overwhelming.