text: job, anal oners role in the organi.zation are all affecteit by previous health' 2V 223. T]he above discusslon considereil solely the effect of a decline in mortality and ioprovement in health on labour supply antl productivity' Some reaearchers have inalicated that causality also flor.rs in the opposite direction. For example 'stuclies in rrany ttevelopeal countries have shown that employe'l persons experience lower norLality than unemployed persons of the same age. this in itself, however 'does not indicate that unemployment leads to greater risk of death and illness since the effects of employment, social class and income are inextricably intertwined. More convincing are studies dettonstrating that fluctuations over time in employment are follor,red by similar fluctuations in nortality. However, sone researchers have also questioned the significance of these results since the structure of the perceived relationships differ over time and place. (iii) 224. The age selectivity of migrants is perhaps the flDst universal characteristics of internal migration. 22/ Accorating to stualies covering a wide ranqe of countries in Oore developed ancl less developed regions, migrants tend to be relatively young and are concentrated in the age group of 15 to 30 yeats. Q/ It is usually during this interval that flost persons enEer the labour force on a permanent basis (at Ieast in the case of males) ' and persons in their zos tend to have among the highest raEes of labour force participation. 24l It is also wi4ely recognized that the search for employment is a major, if not the most important factor in the decision of persons to migrate. 25/ EoE these reasonsr it can be expected that migration has major consequenc.=-For employment in terms of its suppLy and characteristics (such as Iabour productivity, mode of production anil division of Iabour ) . 225. These consequences' holtever, depend on several factors, including the context
analysis: The text discusses the relationship between employment, health, and mortality, as well as the characteristics of internal migration and its consequences on employment. The text does not mention economic development, natural resources, or industry specifically, but rather focuses on the labor market and its related issues.