The human body is a complex set of organs and systems that all work together to sustain life. How does a human body grow and develop over time? Explore the science behind the human life cycle through an encyclopedic-style text perfect for both browsing and deep research. Photos and educational illustrations, include one page with illustrations of male and female genitalia, guide the reader in learning. Real-world examples help explain the life cycle, while body breakthroughs features highlight the scientists and pioneers who made some of the greatest advancements in their fields. Final comprehension questions encourage reflection on what readers have learned.