Just the tip of the iceberg, for the insights on evolution from personnel management to human resource management (HRM).
Personnel management existed in the days of the industrial revolution, where on the theories of Frederick Taylor, due to scientific management, employees are hired on the basis that they will follow through the work process with their specialty and unique skill sets, with disregard to the others within the chain, Hence it's believed that efficiency will be maximized, having specific people with specific skills to run their respective stations efficiently. Simply put in today's content, finding the right person for the right position.
HRM is a totally different school of thoughts, with focus on the core business, and how the whole group can fit in. It is about development and implementation of people strategies, which are aligned/ integrated with corporate strategies. This function helps to ensure that the culture, values and structure of the organization, along with the quality, motivation and commitment of employees contribute to the fullest towards attainment of its goals. Hence from a simple function of hiring right people, it is about the strategy and HR being a strategic business unit, to motivate and reassure the workforce to perform efficiently, and effectively at the same time.
I will provide an addition 4 more points, with 1 citation involved at every point. Then I will conclude it off with HRM being the future of personnel management.