Fungi: The Unsung Heroes of Life on Earth, Part 1 of 2

By the time the first roots evolved, the relationship between plants and fungi was already tens of millions of years old. Fueled by high levels of light and carbon dioxide, plants spread across the world and evolved larger and more complex forms. As plants boomed, the amount of carbon dioxide in the atmosphere dropped by 90%, triggering a period of global cooling. Today, more than 90% of all plant species depend on mycorrhizal fungi.