Life: The First Four Billion Years by Martin Jenkins

Life: The First Four Billion Years takes readers from the Big Bang to the beginning of the evolution of humans. Much of the detail  and the scenarios presented in this nonfiction book for young readers are speculative, as no humans were alive to witness past events in Earth's history.

Earth's story begins with the "Big Bang" which is described as, "Once upon a time along, long time ago, there was, as far as we know, nothing. And then - no one knows how or why -- something happened. A jumble of matter and energy and antimatter - the universe appeared!"

Nine billion years after the Big Bang our sun began to form from a molecular cloud. While most of the material in the molecular cloud went into the new star, some of it began revolving around that star and clumping together. The star became our sun, and the clumps of material revolving around the sun became the planets of our solar system.

From this starting point, author Margin Jenkins takes young readers through the First Ice Age (Early Proterozoic) explaining the Great Oxygenation Event. Other topics include (but are not limited to):

• Boring Billion period in which there were few changes on Earth. The very earliest life-forms were tiny cells known as prkaryotes and eventually eukaryotes.
• Second Ice Age (Cryogenian) which happened around 720 million years ago. This period saw the first fungi, animals, brown algae and red (or green) algae.
• Edicaran period around 570 million years ago. Organisms that lived during this time "remain mysterious to this day."
• Cambrian period which saw many new underwater life forms develop.

Martin discusses the development of burrowing organisms and predators as well as creatures with exoskeletons and the development of jaws and teeth.

Although by the Silurian period fish were the dominant animals underwater, life on land was expanding and evolving. Simple small plants producing spores now offered an escape from aquatic predators and facilitated the move onto land. In the Devonian, giant fungi dominated life on land, while "At some point during the Devonian, fish finally started venturing onto land."  Our only evidence is "...preserved footprints, made by creatures walking across mudflats about 395 million years ago."

Jenkins also offers pages that cover a range of interesting topics as he moves through time including

• March of the Tetrapods
• Continents on the Move which explains the rearrangement of Gondwana and Laurasia into the supercontinent, Pangea
• Disaster explores the Permian extinction which coincided with massive worldwide volcanic activity

Jenkins chronicles the rise and fall of the dinosaurs with pages titled The Start of Something Big, The Age of Dinosaurs, Dinosaurs Take Flight, Life Under the Dinosaurs, and The End of The Giants which explores the demise of the dinosaurs, pterosaurs, giant sea reptiles and ammonites. He writes,
"Whatever the exact causes, the extinctions seem to have taken place over a short period of time, geologically speaking - almost certainly no more than a few tens of thousands of years, perhaps much less."

In the Age of Mammals and The Continents Taking Shape, the rise of mammals and the evolution of various groups of mammals after the great extinction is presented. The Road To Us explores the beginnings of the primates, our ancestors and moves onto the beginnings of the evolution of man.

Discussion

 Life The First Four Billion Years is an informative, large format picture book definitely geared to older readers interested in the history of life on Earth. Jenkins uses lots of technical terms that are explained in the text and also in a Glossary at the back of the book.

Jenkins who is a conservation biologist in England, indicates that he "read hundreds of scientific papers in researching this book". and it certainly shows! His biology background is evident in the use of exact biological terms throughout the text. He also writes that the information  presented was the most current available but that new discoveries may change some of what he has written.

Accompanying Jenkins' detailed text are the mixed media illustrations of Grahame Baker-Smith. There are detailed pencil drawings of the fantastical creatures that lived many eons ago as well as many full page, colour illustrations of significant events in Earth history. Some of these events include the Solar System's birth, the Permian volcanic eruptions and the approach of the asteroid that is believed to have been responsible for the demise of the dinosaurs.

This picture book, rich in scientific detail, will appeal to those who with an interest in Earth history. Readers will get a good sense of how scientists today believe life evolved on Earth while at the same time understanding that there is much we don't know.


Book Details:

Life The First Four Billion Years by Martin Jenkins
Somerville, Massachusetts:  Candlewick Studio     2019
79 pp.