Introduction

Figure 12.1 Although they look different, this bee and flower are distantly related. (credit: modification of work by John Beetham)

Chapter Outline

12.1 Organizing Life on Earth

12.2 Determining Evolutionary Relationships

This bee and Echinacea flower could not look more different, yet they are related, as are all living organisms on Earth. By following pathways of similarities and differences—both visible and genetic—scientists seek to map the history of evolution from single-celled organisms to the tremendous diversity of creatures that have crawled, germinated, floated, swam, flown, and walked on this planet.