Why are some people bitten more than others?

Much progress has been made in describing how it is, in a mechanistic sense , that some vertebrate hosts (species or individuals) are bitten more than others, principally because of their odour or appearance. Little attention has been paid to why, in an evolutionary sense, these particular animals ar e bitten. Irrespective of the proximate mechanisms of host choice, there mu st be an intense selection pressure on insects to feed on those hosts that are most amenable to being bitten. We should be better able to predict host choice by understanding the evolutionary processes at work.