“It’s also clear now that the impact at Chicxulub was not an utterly unique event. Large asteroids and comets have crashed into Earth many times over its 4.5 billion year history. Despite the uniformitarian recycling of the Earth’s surface, there are still traces of some of those impacts.”

In his Foreword, journalist Carl Zimmer explains that the Yucatan impact was one of many asteroid impacts throughout Earth’s long history as a planet. However, the Yucatan impact was significant because of its devastating effects on life on Earth. This passage introduces a discussion on asteroid collisions with Earth and why the Yucatan impact was particularly deadly for plant and animal life.

“Impacts may not only have caused geological trauma, however. They may have seeded our planet. Comets and meteorites carry with them amino acids and other building blocks of life, and some of those raw ingredients may have survived the fall through Earth’s atmosphere. In recent years, some scientists have even proposed that impacts may have delivered living organisms from one planet to another.”

This fascinating hypothesis raises the question of how asteroid impacts may foster life by bringing the “raw ingredients” of life onto a planet from other parts of space. In this passage, journalist Carl Zimmer normalizes the reality of asteroid impacts in Earth’s history and notes how scientists continue to grapple with how such impacts may have informed Earth’s development both constructively and destructively.

“Looking back at the abyss of time which separates us from the Cretaceous, we can somehow feel nostalgia for a long-lost world, one which had its own rhythm and harmony. We feel a special sadness when we think about its plants and animals, fish and birds—for most of the Cretaceous animals and plants are irretrievably lost.”

In this description, Alvarez encourages readers to imagine the Cretaceous period’s plants and animals with affection and respect. In referring to that period’s “rhythm and harmony,” Alvarez emphasizes that it had full, functioning ecosystems that would have continued to thrive if not for the Yucatan impact. In addition, this passage primes readers to anticipate the details of the incredible destruction that the asteroid caused when it collided with Earth.