Members of any given society are united by a shared and partially distinctive culture and networks of social relationships with one another. These ties vary in intensity and distinctiveness depending on the magnitude of the society's store of information and the extent of contacts with other societies. With the acquisition of signals, and later, symbols, the ancestors of modern humans gained the critically important ability to share information acquired through individual experience. These and other later advances in the technologies of communication and transportation laid the foundations for major developments in political and economic systems, social inequality, science, ideology, and other spheres of life.