The Monarch Effect: Surviving Poison, Predators, and People by Dana L. Church

The Monarch Effect presents the remarkable story of the monarch butterfly and how we came to learn so much about this fascinating insect.

The story begins in Chapter One Baby Monarchs and Barfing Blue Jays with the life cycle of the monarch butterfly, starting with the tiny caterpillar which hatches out of a very small egg on the underside of a milkweed plant. The complex relationship between the monarch caterpillar which requires the milkweed plant to survive and the milkweed plant which needs to protect its leaves is described. Key to this relationship are the many survival strategies the monarch caterpillar has developed. These include how to circumvent the tiny spiky hairs on the milkweed leaf and the toxic white oozing liquid of the plant which also acts as a glue. There are several types of milkweed plants and the monarch caterpillars have developed strategies to survive on each. 

Each stage of the monarch caterpillar's life from its five molts to the preparations it makes to pupate, where it forms a chrysalis and undergoes metamorphosis to a butterfly are described with many interesting details.

The research of Dr. Fred Urquhart and his wife Norah are the focus of Chapter Two. Where Do They Go? Urquhart's interest in monarchs began as a boy and carried on through the rest of his life. Dr. Fred Urquhart had plenty of questions about monarch butterflies: Where do monarchs go for the winter? Do they have somewhere safe and warm to rest or do they die off? One article Fred read suggested that monarchs overwinter in Canada and the Northern United States. But he could find no evidence of this. Dr. C.B. Williams, a scientist in England, suggested "...that monarchs fly down to the Gulf Coast in Florida to overwinter and return in the spring."  In 1935, Dr. Urquhart began to investigate this theory by tagging monarch butterflies.

Eventually the Urquharts were able to develop a successful way to tag monarchs and enlist the help of volunteers across North America. They formed the Insect Migration Association and created an annual newsletter. The tagging program showed that the monarchs' flight paths began in northeast Canada and ended along the US Gulf Coast and in Texas. 

In Chapter Three More To The Story, the hard work and determination of Kenneth Brugger and a Mexican woman, Catalina Trail would provide the answer as to where the monarchs overwinter. Their work to determine the overwintering location was crucial to Fred and Norah's research. The Urquharts did not know where the monarchs travelled after they left Texas and the Gulf area. Trail and Brugger would discover two overwintering sites: Cerro Pelon and Sierra Chincua.

What followed was controversy and rivalry after Fred Urquhart published a fourteen-page article in the August 1976 issue of National Geographic magazine. The article paid only a passing mention of the work of Brugger and Trail and failed to honor the promise to keep the overwintering sites completely secret. The reality was that the Urquharts didn't "discover" the overwintering sites as it's likely the Indigenous and local people of Cerro Pelon already knew of them. After all, they cared for the forests and lived on the land.

Urquhart's article did create intense public interest from both scientists and citizens. One person deeply interested was Dr. Lincoln Brower.  In Chapter Four Squabbling Scientists, the relationship between Brower and the Urquharts is explored. What started on friendly terms quickly became a bitter rivalry as the Urquharts refused to share the location of the overwintering sites. Brower had developed a unique method of fingerprinting monarch butterflies using the cardenolide they ingested from the milkweed plants. Milkweed contains a poison in its roots, leaves, milk, seeds and nectar called cardenolides. This fingerprint  allowed scientists to determine where the monarchs had originated based on the  type of milkweed they had ingested. 

Even after the publication of the National Geographic article, the Urquharts would not reveal the location, so Brower took matters into his own hands. He used clues from the article to help: "The overwintering colony...was located on the slope of a volcanic mountain situated in the northern part of the State of Michoacan, Mexico, at a height of slightly over 3000 m." With the help of a fellow scientist, Dr. William Culvert, and topographic maps, Brower located the Sierra Chincua site. Incredibly, Brower and Culvert encountered the Urquharts at the site and an unfortunate accident that resulted in the deaths of millions of monarchs did not improve the situation. Perhaps one of Brower's most significant contributions to monarch butterfly science was the system of cardenolide "fingerprinting" he developed, which allowing researchers to determine a monarch butterfly's location of origin.

Dr. Brower and his team's research is explored in detail in Chapter Five Secrets of the Forest. Brower's research considerably expanded our knowledge "...about monarch butterflies, their predators, and the special climate of the Mexican overwintering sites." They demonstrated that importance of the oyamel forests in the Trans-Mexican Volcanic Belt to monarch butterfly survival. His research uncovered how the monarch migration northward to Canada works. They revealed that  ",,,successive generations of monarchs lay eggs farther and farther north until they reach southern Canada." 

Chapter Six Tracking Migration, explores scientists efforts to better understand monarch migration focusing on the pace of migration and the factors that might be affecting migration. This chapter also explores research into two models, the milkweed limitation hypothesis and the migration mortality hypothesis as reasons for the decline in monarch population.

As research into monarchs expanded, scientists realized they needed to be studying more than just monarch migration, In Chapter Seven, Tracking More Than Migration, the work of several scientists including Dr. Kelsey Fisher and Dr. Karen Oberhauser is featured. Oberhauser initiated studies on monarch egg counts while Fisher, who studied movement ecology, wanted to understand how monarchs find milkweed plants, how they locate the Mexican overwintering sites for the first time and how monarchs know it's spring and time to head north again.

Chapter Eight, Monarch "Smarts" explores in greater detail the science behind monarch migration. Scientists wanted to discover how an insect with a such a tiny brain knows to fly three thousand miles south to an area approximately seventy-three miles wide. In order to understand this, researchers needed to understand monarch biology: researchers studied how their antennae functioned, the chemoreceptors and mechanoreceptors that monarchs relied on, how their eyes work and much more.

Chapter Nine Monarchs Around The World, asks the question "Where did monarch butterflies come from?" To answer this question, the fossil record is considered and genomics, the study of genes has been used to try to answer this question. This chapter also explores where other populations of monarchs are found in the world. 

The significant decline of the western monarch population which is located west of the Rocky Mountains is explored in Chapter Ten Monarch Emergencies. This population spends spring and summer in Nevada, Idaho and Oregon and overwinters along the coast of California. The chapter also considers the decline in the eastern monarch migration. 

In Chapter Eleven Living Near The Monarchy, the efforts to protect the habitat of overwintering monarchs is discussed. The work of Dr. Columba Gonzalez-Duarte has focused on evaluating the Monarch Biosphere conservation model and found it wanting. This model has led to the unintended loss of the traditional way of life for local Mexicans living on the lands and have also led to the proliferation of organized crime. This chapter outlines the many problems of the model both for the butterfly and forest conservation and for the people living in the ecosystem. Instead, Gonzalez-Duarte proposes focusing on the entire habitat instead of just one species might be more successful to saving both monarchs and Indigenous culture and way of life. 

Discussion

The Monarch Effect offers readers a deep dive into the world of the monarch butterfly and the research being done to understand this remarkable and beautiful insect. 

Dana Church provides her readers with fascinating information on almost every aspect of the monarch butterfly. The Monarch Effect opens with a detailed introduction of the life cycle of the butterfly that includes many interesting facts readers will likely not know. For example, many readers will know that the milkweed plant contains a poison, called cardenolide which is found in every part of the plant. But did you know it is also toxic to monarch larvae? Church writes, "Less than half of all monarch caterpillars survive the milkweed's latex...If the amount of latex a caterpillar ends up accidentally eating doesn't kill the, they can recover in five to ten minutes. Otherwise, they end up in a nonresponsive, coma-like state and die." The author describes the various survival strategies monarch caterpillars employ to survive on different species of milkweed and then goes on to describe the rest of the life cycle.

From this point on, the focus of The Monarch Effect is to present the incredible amount of research that has been done in the last eighty years on monarchs beginning with the initial monarch research in the early 20th century by Canadians, Fred and Nora Urquhart into where exactly monarchs overwintered. Like many other scientific endeavours, such research was not without controversy and to that end Church presents a balanced account of the rivalry between the Urquharts and Dr. Lincoln Brower, an American researcher who contributed significantly to our understanding of monarch butterflies. She also highlights the bias of this early research in believing it "discovered" the monarchs overwintering sites, which were already known to the Indigenous peoples of Mexico.

Throughout the book, Church highlights the many questions that arose as scientists learned more about monarchs. "...How do monarchs know when to start migrating? As they migrate, do they fly at a steady speed along the entire journey, or do they speed up or slow down at certain points?" How does weather impact monarch migration? Does the angle of the sun affect the migration? Other researchers wanted to know which US states monarchs arrived at first in the spring. When does the spring migration begin? Why does the timing and duration vary each spring? When the monarchs arrive in Mexico how do they choose where to roost? Do the same butterflies always roost together? How do monarchs locate milkweed plants? How do they decide on which plant to lay their eggs? As Church demonstrates, each piece of information led to more and more questions and required researchers to devise unique ways to find the answers. 

Several chapters are devoted to answering questions about the decline of monarchs and how we can best help the species recover. As with many environmental issues, the problems are complex and multi-faceted. Scientists are now advocating for a combined approach that utilizes both Indigenous and Western traditional science knowledge. It is an approach that considers not just monarchs, but the entire ecosystem and habitat, one that better integrates humans with the natural world they are a part of. This will require removing bias and require international cooperation to succeed.

The Monarch Effect is engaging and informative, written in an easy style, with understandable explanations about the complex problems facing monarch butterflies and the communities they are a part of.  The eastern monarch spans three countries, vastly different ecosystems, and different cultures. The author encourages her readers to become involved in the monarch butterfly recovery efforts by sending monarch sightings to Journey North, helping with tagging monarchs at monarchwatch.org and even counting monarch eggs and larvae through Monarch Joint Venture. The book offers websites that citizen scientists can access to become a part of this important work.

The Monarch Effect is perfect for the budding entomologist and those interested in the natural world. Church includes a detailed Glossary and an extensive References list at the back to help with further research and reading. 

Book Details:

The Monarch Effect: Surviving Poison, Predators, and People by Dana L. Church
New York: Focus Scholastics     2024
309 pp.

Unbreakable. The Spies Who Cracked the Nazi's Secret Code by Rebecca E. F. Barone

Unbreakable tells the remarkable story of how the British, French and Polish worked to break the Enigma code, helping the Allies to win World War II.

The story opens in Warsaw, Poland in 1929.  A "heavy package with a German postmark" arrived at the Polish customs office. Almost immediately, an urgent request came in from the German embassy to return the package which should never have been sent to Poland as it was intended for a German recipient. His curiosity piqued, the Polish customs officer opened the package and found what at first glance looked to be a typewriter. However, there was no ribbon, no carriage to hold paper like a regular typewriter. There were keys which when pressed lit up one of the small circular windows arranged in rows at the top. The Polish customs officer called the Polish cipher agency and two men arrived to examine the machine. Over the weekend they took the machine apart, examined it and reassembled it. It was repackaged and returned to Germany, the delay being that it was the weekend.

Two years later on November 1, 1931, Hans-Thilo Schmidt met up with Rodolphe Lemoine, in the Grand Hotel in Verviers, Belgium. Schmidt was an assistant to the head of the Germain cipher office while Lemoine was the top recruiter and handler for the Deuxieme Bureau of the French military intelligence. Germany had developed a new cipher that no one in the world was able to break. They were using a machine called the Enigma to create the code and it was unbreakable.  Schmidt told Lemoine that he had access to all the information pertaining to Enigma and could give it to France, for a price. When Schmidt began bringing information to France, Captain Gustave Bertrand, a senior officer and a code breaker became involved. The initial information Schmidt brought was not helpful to either the French or the British in solving the Enigma problem. 

Undaunted, Bertrand travelled to Warsaw, Poland in December, 1931 to meet with Major Gwido Langer, head of the Polish cipher office, in the hopes the Polish and French might work together. Bertrand gave Langer the Enigma manuals and instructions that Schmidt had passed along. Langer was ecstatic because up to this point they had been unable to crack Enigma and he had high hopes this new information would help.

 

The Enigma was complex machine in which an electrical signal passed from the keyboard to a plugboard connected to pairs of letters and then to three (or more) rotors and onto a reflecting drum which sent the signal back through the rotors, plugboard to a window at the top of the machine with a letter. Each letter in a message when through this encryption. In order to decode the message, the settings in the Enigma machine of the receiver had to be the same as those of the sender's Enigma. The daily indicator settings for the rotors consisted of three letters, one for each rotor that gave the starting angle for each rotor were sent TWICE at the beginning of the message, unencrypted. These daily settings were called the key.

Meanwhile in Germany in November, 1932 political events were beginning to move quickly. Adolf Hitler had been arrested for the Munich Beer Hall Putsch years ago in 1924 on charges of high treason. He was given a lenient nine month sentence during which time he wrote his infamous Mein Kampf. In this book, Hitler outlined his plans to recover Germany's glory and eliminate the Jews and Polish people whom he considered "inferior races". Germany's problems were all due to the presence of Jews in the country and the world. In the following years, Hitler began to spread his message throughout Germany, that certain races and religions were responsible for the dire economic situation in the country. His political power grew until the Nazis held almost a third of the seats in the German government.

In November, 1932, in Warsaw, Poland, Langer's cipher staff were unsuccessful so he decided to try a new approach: he hired electronics expert Antoni Palluth, one of the two men who had examined the missing Enigma in 1929 and built a replica. He brought along Maksymilian Ciezki, head of the German section of the Polish cipher office. These two men brought in three young mathematicians, Marian Rejewski, Henryk Zygalski and Jerzy Rozycki. Langer's approach changed from linguistics to mathematics and it paid off. 

Working on his own, Rejewski initially had no success using variables and developing mathematical equations that explained how changes to the rotors or the plugboard affected one another. But then Schmidt gave Bertrand "...a photocopy of two tables of the keys for September and October, 1932". Bertrand passed these on to Langer who gave them to Ciezki and then to Rejewski.  At first it seemed like these did not help either, but then Rejewski decided to make a different guess about the Enigma keyboard which was arranged similar to that of a typewriter except adapted for the German language. Instead he wondered if the letters on the typewriter keys were arranged in alphabetical order. When he did this, all his equations worked and the Poles were able to read the German Enigma! It was January, 1933.

But the Polish ciphers had their work cut out for them. With Germany preparing for war, German military and civilian groups, each called a "net", were now using Enigma to send messages. Each net began using different keys and the Polish cipher team had to break each key for each net every day. This exhausting work went on for five years at Saxon Palace in Warsaw. As tensions increased between Germany and Poland, Langer decided to move the cipher team to the Kabaty Woods, ten miles outside of Warsaw to a new built complex called "the Gale". The code breaking continued but was so tedious that Rejewski developed a machine called a bomba, with switches and rotors "that could run through all the combinations from a known rotor starting point."

In Germany the situation continued to worsen.  In March, 1938, Lemoine was picked up the Gestapo and released, German troops crossed into Austria in the Anschluss, the Annexation of Austria, and in September 1938, the Sudetenland area of Czechoslovakia was annexed by Germany. Then in December, 1938, the Germans increased the number of rotors used in Enigma making determining the keys very difficult. 

The English and French still did not know the Polish had been able to read Enigma and their efforts were unsuccessful. Their meeting in Paris, France with the Polish revealed nothing. After Germany invaded Prague Czechoslovakia, Lithuania and Slovakia, Alastair Denniston (head of British codebreaking) and Alfred Dillwyn Knox met with Bertrand, Langer and the Polish cipher team. There they learned that the Poles had broken Enigma years earlier and they obtained a replica of Enigma.

With the British, French and Polish codebreakers struggling to catch up and find a way to break open Enigma, open war began with the invasion of Poland on September 1, 1939. As British codebreakers took up the task of deciphering Enigma, the British navy also set about obtaining any information they could from captured weather boats and sinking U-boats. The race was on to defeat Enigma and win the war.

Discussion

 

Unbreakable is the riveting account of the race by the Allies to unlock the German's Enigma coding machine. Barone masterfully guides her readers through this complex story that involves so many people, some of whom lost their lives to the cause.

Barone pieces together the contributions many Polish, French and British made in the race to break Enigma. Barone, in her Epilogue writes, 

"Breaking the naval Enigma was a testament to teamwork. There was not one hero, not even on team of heroes. The Enigma story played out over the course of more than a decade, with action spread throughout almost a dozen countries: Polish cryptologists worked early and long to crack the Enigma cipher; French and German spies and agents provided intelligence; British codebreakers took up the puzzle; naval ships and sailors seized codebooks from the U-boats; intercept stations relayed messages; and Wrens at the bombes actually ran the machines."

Her cast of characters includes not just the codebreakers like the Polish team of Rejewski, Zygalski, Rozycki, Langer, Ciezki and Palluth, and the British team of Alan Turing who developed the "cryptological bombe", Harry Hinsley, Hugh Alexander, and Gordon Welchman who devised a way to configure the wiring of Turing's bombe, and Joan Clarke. Many others took risks that sometimes cost them their lives. There were the over sixteen hundred "Wrens" (Women's Royal Navy Service) whose task was to operate and maintain the more than two hundred bombes, a physically challenging task that could easily cause a short circuit. There was Gunner "Florrie" Foord who rescued a bag containing "cribs"  and plugboard settings that allowed Turing to set his bombe to work solving the naval Enigma. And there was First Lieutenant Tony Fasson and sailor Colin Grazier who rescued codebooks from the sinking U-boat U-559 at the expense of their lives, codebooks that ultimately broke the naval Enigma. 

Unbreakable manages to explain the workings of Enigma and how it was deciphered in a way that is understandable and engaging to readers. It was a complicated machine and breaking it was not a one step task, but involved many attempts and innovations by the codebreakers.  The story is broken up into four parts, with short chapters, focusing on a single topic with some black and white photographs. Some chapters focus on events while others on specific individuals such as Joan Clarke.

Barone includes an Epilogue in which she informs readers as to the fate of some of the individuals she focused on, a detailed Timeline of events beginning in 1929, and extensive Bibliography for further research. There are also Endnotes providing sources to quotes used throughout the text.

Unbreakable is a fascinating account of the efforts of codebreakers, military men, and spies to crack Enigma which was considered unbreakable by the Germans. 

Book Details:

Unbreakable: The Spies Who Cracked the Nazi's Secret Code by Rebecca E.F. Barone
New York: Henry Holt and Company   2022

260 pp.

A Walk Through The Rainforest by Martin Jenkins

In this exquisite picture book, the author takes his readers on a short walk through the tropical rain forest using the beautiful artwork of illustrator Vicky White.

The journey begins with an illustration showing the tropical rain forest in Malaysia, in a place called Taman Negara. The rain forest is described as "Hot and sticky and pretty dark." Jenkins wonders where all the animals are since the forest contains wild cats, pheasants, pigeons, squirrels, frogs, owls and many different types of insects. However, listening to the sounds in the forest reveals that although they can't be seen, there are many types of animals living there.

One thing that is visible in the tropical rain forest is the trees! There are many different kinds including one called a tualang which is likely two hundred years old. When looking closer at the trees however, most are big and old: there are few young trees. How will the forest replenish itself if there are no young trees? That question is answered as Jenkins continues his walk through the tropical forest, uncovering clues that lead him to determine how tropical rain forests continue to thrive and regenerate!

Discussion

To highlight some of the more fascinating features of the tropical rain forest, author Martin Jenkins poses a question about the lack of young trees in the forest and sets out to find the answer. Along the way, readers uncover some of the hidden animals of the tropical rain forest, and the processes that bring about the growth of new trees in the dense forest. The text is simple and straightforward, with the reader being led through the forest by a description of animals and their behaviours. Clues found in the rain forest suggest answers to the question posed.

The detailed illustrations of Vicky White help young readers visualize a ecological system many will not be very familiar with. These gorgeous illustrations are done in pencil and oil paint and are richly textured. It is these illustrations that really make this picture book special. There's a section on The World's Rain Forests and a section at the back of coloured illustrations of birds, insects and other invertebrates, mammals, and frogs and reptiles, many of which have been included in the illustrations. Readers are invited to go back and see if they can find these creatures in the illustrations.

In an era where many picture books have digitally created artwork, A Walk Through The Rain Forest is a treat, showing readers what traditional illustrations have to offer, while also highlighting some of the features of the tropical rainforest. A must-read book for children and adults alike!

Book Details:

A Walk Through The Rainforest by Martin Jenkins 

Somerville, Massachusetts: Candlewick Press    2022

Bringing Back the Wolves by Jude Isabella

Bringing Back The Wolves recounts the very successful re-introduction of wolves to Yellowstone National Park in 1995. For the previous seventy years, wolves were absent from a large area of the American west. Beginning in the late 1800's the American government placed a bounty on wolves that led to their complete elimination from the West by 1926. While such a policy was a boon to ranchers, it had a major impact on the ecology of the area.

The story begins by describing what happened in Yellowstone as a result of what turned out to be an "unintended experiment": removing one important member of an ecosystem. For seventy years, wolves were gone, completely eliminated due to hunting. In an effort to tame the West, hunters were encouraged to shoot cougars, wolves and grizzly bears.  By 1926, no wolves remained in Yellowstone. Because wolves are a keystone species, their absence directly and indirectly impacted the Yellowstone ecosystem. Elk, coyotes, aspen trees, songbirds and even the soil and streams were affected.

These are all part of the Yellowstone food web, an intricate relationship between animals, plants, birds, water, and soil. The absence of an apex predator, the wolf, allowed elk to increase in population, which led to over-grazing of grass and trees. The result was a transformed landscape and more impacts throughout the food web. But in 1995, that was about to change.

When wolves were re-introduced into the park in late January of 1995, there was plenty of prey for wolves. For the first decade after the wolf reintroduction, elk herds were so large, each wolf killed about eighteen to twenty-two elk per year. As the elk population began to decline, changes began to happen in the Yellowstone ecosystem. The park vegetation began to re-establish itself , with more grasses, and full grown trees. The populations of other canids, coyotes and foxes in the park also changed. As the years went by and the wolf population grew, the ecosystem began to heal and researchers saw more and more changes, all of them bringing about a more balanced natural environment.

Discussion

Bringing Back The Wolves is both engaging and very informative. Isabella has covered all the bases in this detailed nonfiction picture book that explores the ways the re-introduction of wolves into Yellowstone National Park healed local ecosystem. Bringing Back The Wolves explains the complex relationships between the many species of animals and plants in the Yellowstone ecosystem. Readers will learn how the absence of the wolf harmed these relationships and how their return brought each part of the ecosystem back into balance. 

For example, the return of the wolves resulted in more elk carcasses for grizzly bears, allowing them to better prepare for the winter. These carcasses also provided food for various types of decomposers such as insects, bacteria and molds, which break down the carcass enriching the soil. More insects mean more food for birds.  Fewer elk also allowed willow, cottonwood and aspen trees to grow back, providing homes for birds, beavers and other animals. Fewer elk  allowed berry bushes to mature and produce more fruit for insects, birds and black bears. The interconnectedness in the food web is well explained in easy to understand text. Each page features colourful illustrations rendered in Photoshop by artist Kim Smith.

Isabella avoids any discussion about the controversy of the wolf reintroduction into the park or the delisting of wolves as an endangered species. This book focuses entirely on the ecology of the wolves in relation to Yellowstone and what scientists have learned in the last twenty-five years.

As Isabella concludes, "Twenty-five years after their reintroduction, about 500 wolves roam the great Yesllowstone ecosystem, staking their claim in the food web. Wolves have helped to balance the ecosystem just by being themselves, apex predators. But perhaps even more important, studying the wolves has exposed just how complex and interconnected the ecosystem is, revealing surprising links no one could have imagined."

Bringing Back The Wolves is highly recommended for anyone interested in ecology, wolves and for unit studies in school. Isabella rounds out the information with a Glossary, a list of Resources and an Index.

Those interested in reading more about the wolves in Yellowstone National Park are directed to the US National Park Service website.

Book Details:

Bringing Back The Wolves: How a Predator Restored An Ecosystem by Jude Isabella
Toronto: Kids Can Press   2019
39 pp.

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.

Prehistoric Dinosaurs, Megalodons, and Other Fascinating Creatures of the Deep Past by Kathleen Weidner Zoehfeld

Prehistoric Dinosaurs takes readers on a journey backwards in time beginning with our own epoch, the Anthropocene.

Readers start with the Holocene epoch which began approximately 10,000 years ago and is the most recent in the Cenozoic era. During this time, humans evolved, the Earth warmed resulting in the retreat of vast ice sheets. This allowed humans to migrate and settle in most parts of the world.

The Pleistocene which began approximately 2.6 million years ago saw the most recent ice age. With climate cooling, ice caps formed at the North and South poles. There were interglacial periods when the climate warmed allowing forests and mammals to flourish. It was a time of saber tooth cats such as Smilodon. Prior to this, during the Neocene epoch (23 million to 2.6 million years ago), mammals began to dominate the Earth.

The Neocene was preceded by the Paleocene which began 66 million years ago. The climate was warm allowing large rain forests to grow and  new types of mammals to evolve. Early primates began living in the trees during this time.

Before the Paleocene, the Cretaceous Period saw the reign of the dinosaurs which were a very diverse group of animals. There were meat-eating dinosaurs such as Tyrannosaurs, as well as plant-eating ones such as Spinops. Flowering plants or angiosperms also developed during the Cretaceous Period providing fruits as a food. In the sea, giant mosasaurs, turtles and ammonites flourished. Scientists have evidence that the Cretaceous experienced a mass extinction even that destroyed seventy percent of the life on Earth. The cause is believed to be an asteroid that crashed in what is now Mexico, resulting in the Earth being overwhelmed with dust and smoke, blotting out the sun. This catastrophic event is believed to be responsible for the demise of the dinosaurs.

It was during the Jurassic, 201-145 million years ago, that the largest land animals developed. These were the sauropods. During this time, the super continent known as Pangea began to break up. This began with the break up of North America from Europe and Asia and later Africa from South America.

About 252 million years ago, the ancestors of dinosaurs and other reptiles were evolving. At this time dinosaurs were small, inhabiting most areas of Pangea.

The Permian period (299- 252 million years ago) saw the formation of the supercontinent called Pangea from the collision two great land masses. At this time there were amphibians, reptiles and pre-mammals. Most were predators who ate other predators.Although there were many plants, they were consumed mostly by insects. The end of the Permian is characterized by a great extinction resulting from an extended period of widespread volcanic activity. It is believed over ninety percent of life on Earth was destroyed.

Before the Permian, the Carboniferous was a time of giant trees and towering ferns. These lush forests were filled with many different arthropods, amphibians and the first reptiles.From 419 to 359 million years ago, the Devonian period saw the development of the first trees and forests, the first insects and spiders and the first four-legged animals such as salamanders.  Prior to the Devonian, during the Silurian (443 to 419 million years ago), temperatures on Earth were slowly rising, allowing new life forms to develop. The first fish with jaws developed allowing predation to occur, as well as the evolution of eurypterids ("scorpion-like arthropods) which could grow to be very large.

In the Ordovician (485 to 443 million years) most life existed in the oceans. Snails, clams, nautiloids, trilobites and conodonts as well the world's first fish lived in the water. This period was characterized by the expansion of coral reefs across the world. The period before the Ordovician is called the Cambrian and this era saw the explosion of life on Earth. This sudden increase in life forms is called the "Cambrian Explosion". Trilobites, a primitive arthropod, dominated the Cambrian period which is sometimes referred to as the "Age of Trilobites".

Finally, the period before the Cambrian is known as the Ediacaran, some 4.6 billion to 541 million years ago. The amazing story of life on Earth began during this time and little is known about the creatures who lived during this phase.


Discussion

In Prehistoric Dinosaurs, Megalodons and Other Fascinating Creatures of the Deep Past, author Zoehfeld has chosen to tell the story of life on Earth beginning with the modern epoch of the Anthropocene (which we are now living in) and moving backwards through time to the very beginning. This makes it difficult to fully understand how life developed from simpler forms to more complex ones, how the climate and the land masses changed over time and how catastrophic events shaped life and the world afterwards. Therefore, it is recommended that readers start at the back of this book and read backwards to the front! Reading in this way works superbly, making the timeline of events more logical and understandable.

Zoehfeld's simple text gives readers a good understanding of the changes that occurred through each period and there are detailed, full colour illustrations which provide a sense of what the Earth may have looked like during each time period as well as the creatures that could be found in the seas and on land. The author includes many interesting facts for each period, and sets aside small areas on each page to explain certain events or to provide more details. For example, there are short, simple explanations of how coal formed, supervolcanoes, how dinosaurs walked, mass extinctions, ice ages and many other topics.

This book was produced in association with the Smithsonian's National Museum of Natural History. A more concise title with a more engaging illustration on the cover is also recommended. Overall, an  interesting presentation of the development of life on Earth. However, the claim on the book's back cover, "What's the best way to see the past? From the present, of course!" didn't work for this reader!

Book Details:

Prehistoric Dinosaurs, Megalodons, and Other Fascinating Creatures of the Deep Past  by Kathleen Weidner Zoehfeld
Greenbelt, Maryland: What on Earth Publishing   2019
45 pp.

Charles Darwin's On The Origin of Species by Sabina Radeva

Up until the mid 19th century, it was generally believed that all life on earth was created within the last few thousands of years,  at the same time and had generally remained unchanged. However some scientists began to consider that animals may have changed over time to their present form.

Charles Darwin was an English naturalist who enjoyed observing the natural world. During a voyage around the world aboard the HMS Beagle, Darwin began to form ideas about life on Earth based on his observations which he accurately recorded.

After twenty years of writing and researching, Darwin published those ideas in 1859 in a book titled, On the Origin of Species By Means of Natural Selection. He defined species as "groups of living things that look alike and can have babies together." Members of a species might have "variations" such as different colouring but overall they resemble each other. A perfect example are pigeons which Darwin believe descended from the rock pigeon but now have many variations.

Variations can occur through domestication, from specialized breeding programs. For example, farmers can breed cows who make more milk. In the natural world, variation also occurs. Darwin had visited the Galapagos Islands and noted that finches on the island had variations in the shape of their beaks, allowing them to eat specific kinds of fruit. For example, some finches had large beaks for cracking open large seeds, while others had long and sharp beaks to eat only cactus flowers.

Although animals and plants can often easily reproduce and have numerous offspring, it is difficult to survive in the wild. Those best adapted are the ones who succeed. Many adaptations help a species survive and over time small adaptations add up leading to new species better adapted to a new environment.

Darwin did not know how life began on Earth but he believed, based on his observations, that life on our planet is constantly adapting and changing. He called this process "natural selection" which "makes living things better adapted to where they live. Once animals with more useful traits appear, they will compete and replace those that are less adapted."  Darwin also believed that all living things were interconnected in a vast tree of life.

His theory, unique and earth-shattering in the 19th century, also led scientists to ask even more questions? If this process was happening, where was the fossil evidence for the transitional forms as adaptations led to more significant changes? Darwin felt that this could be explained by the fact that the creation of fossils is a difficult process requiring a perfect set of conditions. Animals must be covered quickly by sediment when they die in order to be preserved and even then the soft parts of animals are rarely fossilized. The conditions for fossils to be preserved must be ideal.

Natural selection also works on instinct, or how animals inherently behave. Darwin also believed that migration, that is a species moving from one area to a new area, also plays a role in change. Darwin also noted that embryos, the very first stages of new life, all show common features suggesting a common beginning. The process of evolution continues today as all life on earth adapts to the constantly changing world.

Discussion

Author Sabina Radeva presents a picture-book adaptation of Charles Darwin's famous work, On The Origin of Species. Radeva who has an M.Sc. in Molecular Biology from the Max Planck Institute, was intrigued by an illustrated copy of On The Origin of Species. However, she realized that most people would never read it because of the dense text. Having switched careers and now working as a graphic designer, Radeva was still interested in combining her science background with her talent as an illustrator. She felt that children could better understand the concepts in Darwin's theory through the use of pictures.

The author admits to leaving out "some information from Darwin's original text because the concepts were too difficult for young readers." but this works for the topic of evolution, distilling it down to the important ideas. Overall this picture book gives a good summary of Darwin's big idea, that life on Earth is constantly adapting and that this occurs through a process Darwin called natural selection. Radeva presents the basic parts of Darwin's theory, explaining how he came to develop it through his observations. And therein lies the lesson of the book: Radeva believes that from Darwin's story, "...children can learn the power of observation and recognize how curiosity about the natural world can lead to incredible discoveries." In an era where attention is focused almost entirely on the virtual world, Radeva's book, and Darwin's story are reminders that the natural world is full of discoveries waiting to be made.

Radeva avoids most of the controversy surrounding the theory of evolution but does explain some misconceptions surrounding evolution in a separate section at the back of the book. Appropriately titled Misconceptions, she explains what evolution is and is not. In the Appendix, Radeva explains many scientific concepts including DNA and genes, inheritance, variations and mutations, natural selection, epigenetics ( relatively new field of study in which lifestyle and life events have an effect on gene expression) and comparative embryology. There is also a Glossary and a Recommended Reading section.

Charles Darwin's On The Origin of Species is a good starting point for young readers (Grades 1 to 6) to explore evolution and natural selection. To learn more about Charles Darwin and his amazing voyage, young readers are directed to One Beetle Too Many: the Extraordinary Adventures of Charles Darwin by Kathryn Lasky.

Book Details:

Charles Darwin's On The Origin of Species by Sabina Radeva
New York: Crown Books for Young Readers     2019