The biological effects of human intervention.

The author discusses human intervention in the environment the resulting biological changes and their impact on population trends. "Several types of intervention are distinguished: Primary or deliberate--measures taken to achieve a desired aim; [and] secondary or incidental--arising in the course of other actions. Both interventions may be quantitative or qualitative. An example of the primary type is recent control of fertility in China. A secondary intervention is illustrated by the demographic situation in England during the last century. The third example measles control in the Gambia shows the difficulties of implementing a deliberate programme and the need to include additional measures to influence...other factors." These three examples illustrate both the impact of such interventions on the human gene pool and the difficulty of measuring such changes. (EXCERPT)