Are human studies possible? Some thoughts on the mutation component and population monitoring.

The concept of the mutation component of a genetic trait is discussed and its relation to heritability investigated. It is found that for qualitative traits held in the population by opposing directional selection and mutation, the mutation component equals the broad sense heritability. The mutational component of a quantitative trait with an intermediate optimum is found generally to be between half and one times the (narrow sense) heritability of the character. Although more work on this matter is required, the finding of a relationship between mutation component and heritability should allow us to make better predictions regarding the likely impact of an increased mutation rate on the human population. Some statistical problems relevant to the detection of an increased mutation rate are also discussed.