What you’ll learn to do: Discuss the history of the study of life and the diversity of life on Earth

Figure 1. Our planet

Viewed from space, Earth offers no clues about the diversity of life forms that reside there. The first forms of life on Earth are thought to have been microorganisms that existed for billions of years in the ocean before plants and animals appeared. The mammals, birds, and flowers so familiar to us are all relatively recent, originating 130 to 200 million years ago. Humans have inhabited this planet for only the last 2.5 million years, and only in the last 200,000 years have humans started looking like we do today.

All that said, the study of “life” has been practiced for hundreds of years and branches like the limbs of a great tree into a host of different areas and specialties. Before we can focus on the subdisciplines of biology, it is important that we first touch upon both the history of biology as well as the vast biological diversity on which it focuses.