Chapter 1: Introduction to Biology

Viewed from space, Earth offers few 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 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.

Introduction to Interactive Learning

The goal of interactive learning is to promote engagement with and retention of the concepts and information being studied. The interactive learning activities in this open textbook support self-directed practice and are not recorded assessments. Use the interactive learning activities to:

• Search for key points at the start of each chapter
• Interact with videos, and
• Practice review questions within the chapter sections.

Watch an introduction to interactive videos