[Developing countries] The actual flow of workers into industry in developing countries may be subject to powerful restraints arising from peculiarities of the social organization and culture pattern of the population. The modern industrial system assumes a certain degree of occupational mobility. But occupational mobility, facilitating the upward movement of workers to jobs on a higher economic level, may have little meaning in societies where production is organized on a family basis, and occupation is inseparable from the family status and kinship roles. In some societies, the immobilizing influences of a closely-knit family organization or well-integrated local community may be augmented by the checks and restraints of a wider social system. Caste systems and various forms of peonage, servitude or bondage, including indebtedness, segregation laws and colour bars are all detrimental to the manpower and mobility requirements of an expanding industrial economy. These handicaps are widespread among less developed countries, though there are significant local and regional differences in the degree to which they actually limit the size and effectiveness of the available labour force. In general, these social factors are more potent in Africa than in Latin America or Asia, where urban labour reservoirs tend to be much larger.