How and when did life on Earth get to be the way it is today?

• Imagine a world without bees, butterflies, and flowering plants. That was Earth 125 million years ago.
• Turn back the clock 400 million years, and there were no trees.
• At 450 million years in the past, even the earliest insects had not yet developed.
• And looking back 500 million years-a half-billion years before the present-the land was devoid of life, which at that time flourished in a profusion of strange forms in the oceans.

These and other major turning points are the amazing story of evolution, the most remarkable force in the history of Earth, the organizing principle throughout the biological sciences, and the most important mechanism scientists use to understand the varieties of life on our planet.

To learn about these major transitions, each of which brought forth new possibilities for life, is to embark on an unforgettable look into the past. It's also a captivating opportunity to get a deeper understanding of how evolution works, to draw intricate connections between living things, and to think about life-not just yours but the lives of everything around you-in new ways.