Earth’s green evolution gave rise to everything from dinosaurs to dandelions

Paleontologist and science writer Riley Black aims to give evolutionary biology the narrative drive and verve of fiction.

In her latest work, “When the Earth Was Green,” Black selects 15 geologic epochs and certain keystone species to create a journey of the sights and sounds, textures and smells, actions and reactions of plants, animals, and habitats.

Her goal is not just to describe the interplay among species, but also to show that biology is about what comes next. Organisms and ecosystems are always affecting one another, and each geologic iteration makes way for biological adaptations and changes, up to and including extinction.

As a paleontologist, Black is naturally drawn to dinosaurs and what happened to them. But she goes back – way back – to explore how the proliferation of plant life supported dinosaurs and enabled them to grow into the massive creatures that have captured our imaginations.

She describes how photosynthesis predated the appearance of plants by millions of years.

She writes, “Plants have only ever borrowed the ability, an accidental gift when ingestion turned into an ability to change components of Earth’s abiotic makeup into living, growing tissue. The greening of the planet was so widespread that it opened opportunities for some plants to give up on photosynthesis altogether, instead taking a little from the great trees around them to thrive in the shade.”

“When the Earth Was Green” moves around the planet, era by era, from Oman to Ohio, New Mexico to New Zealand, offering slices of life from the grasslands to the oceans. The writing is often evocative: “The carbon dioxide and methane released from deep within the planet have fed a new warming pulse, another chapter in the seemingly endless summer of the dinosaurs.”

Also enjoyable are the entertaining descriptions of plant and animal interactions similar to those we’ve witnessed in our own lives.

For example, how cats and catnip became an item: “Machairodus [a type of saber-toothed cat] is just a few chews into the swath of low-growing catnip before she leans into a deep stretch, pushing her chin low to the ground as her massive mitts slide through the clumps of catnip. It just feels so good.” The plant has developed a compound to ward off insects that just happens to also attract felines.

In another example, Black writes about how tree resin turns into amber. A mosquito becomes trapped in the sticky resin and then becomes entombed, preserving the fossil record: “The minerals infiltrate and replace her [mosquito] tissues, beginning to copy them and even fill the tiny cavities in her body. Her body is acting as a mold for what’s becoming a mineralized cast.”

There are also snippets in the book that validate our own present-day causes and concerns, like No Mow May: “Those invertebrates that don’t perish for the season, leaving behind their eggs for the spring, have no choice but to shelter in place, and the evolution of trees and shrubs that shed their leaves have been among the happiest accidents in the long history of forests.”

Black is able to convey both the elemental randomness and the singular persistence of life from the beginning of time. In the end, “When the Earth Was Green” offers a few new twists on Charles Darwin’s dangerous idea: “Evolution doesn’t set the beat so much as follow it, however. Survival doesn’t just depend on what a species is today, but what it might become tomorrow.”