gies have opened opportunities for entirely new industries and have revolutionized others (Teitelman, 1989; National Research Council, 1986a). The explosion of scientific activity, both basic and applied, created a wellspring of demand for scientists, engineers, technicians, and health professionals. However, the commercialization of science did not simply enlarge existing fields; it triggered a proliferation of new technical occupations via two processes: specialization and the elimination of low-level work tasks.
As the stock of knowledge in a discipline becomes more complex, scientists and related professionals find it difficult to remain generalists. Although generalists may be effective at screening problems, they are less prepared than specialists to advance a field's knowledge or provide state-of-the-art services. Because the latter activities are highly valued in technical cultures, most of the sciences and professions have adopted a strategy of carving cognate areas into ever narrower subfields. Specialization increases the number of professionals by opening up new territory and by requiring collaboration: under a regime of specialization, few individuals can execute alone tasks that require both breadth and depth of expertise.
Overburdened professionals have also sought to curb workloads by allocating routine duties to other groups. Many of the technician occupations that have flourished in the latter half of the 20th century originated in the giving off of "dirty" work by the established professions. The phenomenon has been most visible in the health care industry: licensed practical nurses and an expanding array of technicians have coalesced into occupations around tasks discarded by their more prestigious colleagues (Hughes, 1958). The dynamic is also prevalent in other industries, where it has given birth to a plethora of technical occupations ranging from the well-known—paralegals, electronics technicians, chemistry technicians—to the obscure—test and pay technicians (see Kurtz and Walker, 1975).
Increasing life spans and the upward shift in the age distribution have also contributed to the increasing prominence of professional and technical work. As people age, they require more