Introduction

Living organisms display an enormous range of forms, sizes and ways of life. Since prehistoric times, human beings have depended on this diversity for food, medicine, shelter and safety, and that practical need pushed people to tell one organism apart from another. Over generations this everyday habit of distinguishing and identifying organisms grew into a formal branch of biology called classification, and classification itself matured into the broader science of systematics.

This is not a modern invention. Methods of grouping living things can be traced back to antiquity — ancient Indian, Greek and Roman scholars all made early contributions towards systematising the study of nature, long before the rule-based taxonomic methods used today were developed.