Introduction

Insects such as the ubiquitous butterfly belong to the huge phylum Arthropoda (creatures having paired, jointed appendages and a chitinous exoskeleton). There is no indication this phylum evolved from some other group. Indeed, arthropods “have a rich fossil record extending to the very late Precambrian period” as arthropods.¹

The lowly fruit fly (Drosophila) is the research biologist’s friend in fields such as biomedical science, genetics, and developmental biology. The insect takes up little space, is easily fed, has just four pairs of chromosomes, and reproduces rapidly.

One of the mysteries of evolution (there are so many) is the origin of teeth.