A Work in Progress (JOURNYS Original Research Article on CRISPR-Cas9)

In the late 19th century, Friedrich Miescher isolated an unknown substance, something that was neither a protein nor lipid. Since it was found in a cell nucleus, Mischer named it a nuclein, later renamed deoxyribonucleic acid, or DNA for short [1]. However, it wasn’t until the mid-1900s that DNA—not protein—was proven through several experiments involving bacteriophages to be the macromolecule that carried genetic material. After that, two men by the name of Watson and Crick published a succinct paper detailing the double-helix structure of DNA, another milestone in the study of science and biology [2], and in 2003, the entirety of the human genome was sequenced and mapped.

It seems as though there are new discoveries every day in the field of science, especially in the studies of DNA and genetics. Since the discovery of DNA, there have been an increasing number of people and experiments invested in learning even more about the so-called “blueprint of life.” But even in  the rapidly developing area of genome engineering and editing, there are discoveries that stand out. A particularly outstanding recent development is CRISPR-Cas9.

Today, there are thousands of known human genetic disorders, such as hemophilia, Huntington’s disease, Parkinson’s disease, and sickle cell disease, to name a few [3]. Now, to cure these genetic diseases, imagine using a new type of gene editing technology that could go into any human genome and cut out specific abnormal or disease-carrying segments of DNA, replacing them with different, more desirable strands of DNA [4]. Imagine using the same technology to purposefully engineer specific traits into or out of animal or human DNA; this is the ultimate goal of CRISPR-Cas9. Although the technology isn’t sophisticated enough to accomplish such specific engineering yet, CRISPR-Cas9 certainly opens up many intriguing opportunities in the world of genetic engineering.

The history of CRISPR, or Clustered Regularly Interspaced Short Palindromic Repeats, begins a little further in the past than one might expect. In the decade leading up to the 21st century, scientists began identifying unusual repeating sequences of DNA in bacterial genomes. These short, repeating bacterial sequences of DNA were CRISPR. However, in the same way that the discovery of DNA proved to be underwhelming until DNA was proven to be genetic material, the discovery of CRISPR was of little importance until 2007, about thirty years after CRISPR were first identified. In a study led by Rodolphe Barrangou and Philippe Horvath, two researchers working at the company DuPont, scientists discovered that CRISPR were actually a type of defense mechanism used by bacteria against their assailants: viruses, phages, and plasmids [5]. The bacterial immune system breaks down the intrusive virus DNA, cutting the pathogenic DNA into unusable segments, which are then saved and inserted into the bacteria’s DNA, stored in the CRISPR spaces with an enzyme called Cas9 that has the ability to cut across DNA. The segments of virus DNA are then transcribed into RNA strands called guide RNA, or gRNA, which function as tags, duplicated from and designed to stick to viral DNA. Thus, if the bacteria is attacked by the same virus, gRNA identifies and tags the virus. Then Cas9 can cut up the intruder virus’s DNA, completely eliminating the virus. Essentially, bacteria can use old virus DNA they saved to identify new intruding viruses, and then Cas9 cuts up the intruding viral genome, protecting bacteria from harm [6, 7].

Scientists were quick to see how the CRISPR-Cas9 technique could be applied to human genetics. In 2013, researchers were able to use a version of the CRISPR-Cas9 system to cut DNA in both mouse cells and human cells using RNA guide sequences [8]. CRISPR-Cas9 cut the mouse and human DNA precisely where the scientists wanted it to, which showed the CRISPR-Cas9 system’s first real potential for becoming a precise gene-editing technique—not only for bacteria, but mammals and humans as well. Now, using any strand of selected DNA, CRISPR-Cas9 can potentially identify and edit desirable genes into or out of any human genome.

While  the broader field of gene-editing is not a revolutionary idea, with the CRISPR-Cas9 technique, gRNA only tags dangerous viral DNA, only neutralizing  dangerous viruses and making the CRISPR-Cas9 technique more effective and accurate than other genome editing techniques. The CRISPR-Cas9 technique’s precision, accuracy and affordability have made it one of the most popular techniques for gene-editing in 2016 [6, 9]. For example, a group of Chinese scientists have planned on using the CRISPR technique on a human patient, testing engineered cells in treating lung cancer [10]. Though the treatment is still recruiting participants, the experiments plans on inserting a programmed cell death gene into blood cells with CRISPR, then reintroducing those edited blood cells back into the patient. In cancer cells, cell death signals are ignored, resulting in the uncontrollable division of these cells. The introduced death gene is meant to prevent the metastasis and continued proliferation of these cancer cells. Numerous other experiments—from growing longer cashmere goat hair to engineering tougher crops to developing immune cells to attack cancer—involve CRISPR, which continues to be a diverse technique applicable to many fields [11, 12]. In the case of the cashmere goats, the researchers, using CRISPR, edited a specific follicle gene that resulted in longer and more cashmere [11]. For crops, CRISPR has been also used to successfully create strains of grain that are genetically engineered to be more disease-resistant and drought-resistant [12]. The success of these experiments show how many possibilities CRISPR can offer science and the world.

However, as with any new technology, there are arguments against the use and the effectiveness of CRISPR-Cas9. Ethical arguments against CRISPR and gene-editing include the fear that the ability to manipulate DNA may result in abnormal and unnatural animals or even humans. Selective control over undesirable or desirable traits may lead to eugenics [13, 14]. Ethics aside, many consider CRISPR-Cas9 too novel and too untested to be a viable option for gene-editing. Only in its early stages of development, CRISPR-Cas9 still requires refinement to answer criticism. How can CRISPR-Cas9 treat humans if no two human genomes are identical? Why would CRISPR be used when there are safer, more tested options on the market? What if removing a gene containing a disease makes the disease worse? Furthermore, the large size of the human genome, in comparison to bacterial DNA, often has identical sequences of DNA, which CRISPR-Cas9 could cut accidentally [14]. Nevertheless, since its early results with mammal DNA and plant DNA are promising, with more tests and more time, CRISPR-Cas9 may prove these critics wrong, and become the next breakthrough in science.

Although  CRISPR-Cas9 currently remains in its developmental stage, with research focused solely on isolated human cells and animal subjects, it’s evident that the technology is quickly developing. Like the rest of the research dedicated to DNA and genetics, CRISPR-Cas9 has gained popularity with time. From 2011 to 2016 alone, there was a 1,453% increase in number of published scientific papers about CRISPR and for good reason: the potentials of CRISPR are limitless [15]. Whether it be creating more prosperous crops, curing cancer or altering human embryos, CRISPR-Cas9 has  the potential to impact all aspects of human life and is a scientific development that deserves attention in the future.

Works Cited

1. Dahm, Ralf. "Discovering DNA: Friedrich Miescher and the early years of nucleic acid research." Human Genetics Jan. 2008: 565-81. Print.
2. "The Francis Crick Papers: The Discovery of the Double Helix, 1951-1953." U.S. National Library of Medicine. National Institutes of Health. Web. 18 Jan. 2017.
3. "Specific Genetic Disorders." National Human Genome Research Institute (NHGRI). 18 Jan. 2017. Web. 19 Jan. 2017.
4. "CRISPR/Cas9 GENE EDITING." CRISPR Therapeutics. Web. 17 Jan. 2017.
5. Barrangou, Rodolphe, and Philippe Horvath. "The CRISPR System Protects Microbes against Phages, Plasmids." Microbe 2009: 224-30. Print.
6. "Research Highlights: CRISPR." Broad Institute. Broad Institute, 2016. Web. 19 Jan. 2017.
7. Pak, Ekaterina. "CRISPR: A game-changing genetic engineering technique." Science in the News. Harvard University: The Graduate School of Arts and Sciences, 31 July 2014. Web. 19 Jan. 2017.
8. Cong, L., F. A. Ran, D. Cox, R. Barretto, N. Habib, P. D. Hsu, et. al. "Multiplex genome engineering using CRISPR/Cas systems." National Center for Biotechnology Information. U.S. National Library of Medicine, 15 Feb. 2013. Web. 19 Jan. 2017.
9. "What is CRISPR-Cas9?" Your Genome. Wellcome Genome Campus, 19 Dec. 2016. Web. 19 Jan. 2017.
10. "PD-1 Knockout Engineered T Cells for Metastatic Non-small Cell Lung Cancer." ClinicalTrials.gov. U.S. National Institutes of Health, Nov. 2016. Web. 19 Jan. 2017.
11. Wang, Xiaolong, Bei Cai, Jiankui Zhou, et. al. "Disruption of FGF5 in Cashmere Goats Using CRISPR/Cas9 Results in More Secondary Hair Follicles and Longer Fibers." PLOS Journals. PLOS ONE, 22 Nov. 2016. Web. 19 Jan. 2017.
12. Talbot, David. "10 Breakthrough Technologies 2016: Precise Gene Editing in Plants." MIT Technology Review. MIT Technology Review, 21 Feb. 2017. Web. 16 Apr. 2017.
13. Andrew, Elise. "Genome Editing Poses Ethical Problems That We Cannot Ignore." IFLScience. IFLScience, 15 Aug. 2016. Web. 16 Apr. 2017.
14. Rodriguez, E. "Ethical Issues in Genome Editing Using Crispr/Cas9 System." OMICS International. OMICS International, 24 Mar. 2016. Web. 16 Apr. 2017.
15. "STAT’s stats of the year: 2016 by the numbers." STATnews.com. STAT, 28 Dec. 2016. Web. 19 Jan. 2017.

An Ongoing Study (Review of “The Sixth Extinction”)

Invention and Arrangement:

The Sixth Extinction: An Unnatural History falls under the nonfiction genre, but it’s a scientific research as well as a narrative. Elizabeth Kolbert tells the history of extinction, starting from prehistoric ages and ending with the present day, in a narrative fashion, presenting her scientific facts and explanations in a narrative fashion.

The Sixth Extinction consists of thirteen chapters. Each chapter revolves around a species that Kolbert researches -- either through investigative, person research, or informational research. Each one of these species is either on the brink of extinction or is extinct. The species and chapters are not ordered chronologically -- the first chapter deals with Panamanian frogs, a subspecies of which went extinct in the wild in 2007 while the second chapter involves mastodons that died out 10,000 years ago -- but rather, ordered in a way that best introduces the subject of extinction. Underlying each of Kolbert’s chapters is research regarding the history of the definition of extinction, theories of evolution, climate change, and other factors -- such as acid rain and ocean acidification -- that contribute to the rapid decrease in diversity today. In the first part of her book, Kolbert mostly follows the work of George Cuvier to explore the definition of extinction -- which did not exist until the early 1800s. As she continues to research the extinction of species such as the auk, ammonites, and coral reefs, Kolbert explains the theories hypothesized by evolutionists such as Darwin and Lyell. The evolutionists and other scientific figures that Kolbert describes or meets are not necessarily involved with the species in their respective chapter; instead, Kolbert connects these people to species with similar ideas or theories. In this way, with every chapter, as her novel and her research progresses, Kolbert adds more and more layers to the issues and the history behind her cause, beginning with the definition of extinction and then building up evidence from the world today that correlates with that definition, to eventually claim that the modern world is in the midst of its sixth major extinction.

After an introduction and a beginning chapter on the rapid decline of exotic frogs in Latin America, Kolbert begins digging into the main topic of her book: extinction. She begins by introducing extinction as a scientific concept that children often struggle with. She draws parallels between these children and several famous historical figures -- including Aristotle, Pliny, and Carl Linnaeus -- to show that evolution is not a concept that can easily be reached by just using logic. To start, she begins by defining extinction. Kolbert follows a group of paleontologists who unearth giant mastodon bones, fossils that “confounded everyone who examined them” (26). At the time, the idea of extinction did not exist, and scientists believed that an enormous creature was roaming about the earth unseen until George Cuvier, a zoologist, hypothesized that species could die out and become extinct. Kolbert visits the museum that Cuvier worked in more than two hundred years ago to examine the same mastodon teeth that Cuvier examined, describing them as “the Mona Lisa of paleontology” (31). She explores both the accuracies and the inaccuracies of Cuvier’s theories, but more importantly, Kolbert recognizes the beginnings of the documentation of extinction, providing solid context and background information for the rest of her novel.

Kolbert adventures to Castello Aragonese, an island in the Tyrrhenian Sea, where she looks at the effects of carbon dioxide on the local biosphere to estimate the effects of human waste -- as in fossil fuels, coal, natural gases -- on the ocean environment. She follows two marine biologists to swim an acidified bay and view the effects of carbon dioxide: she finds that a string of organisms have become bleached out, losing their color as they are exposed to more and more carbon dioxide. To add to her personal investigative research, Kolbert researches the industrial revolution, a human development that has contributed “some 365 billion metric tons of carbon to the atmosphere” (113). It is in this chapter that Kolbert begins to explore in particular how human action or inaction impacts the world. Previously, Kolbert only addresses the history of extinction and the natural causes for extinction -- like the meteor that marked the end of the Cretaceous period -- but now she begins to address the effect that humans have had on the environment. It marks the end of the first part of her novel, her discussion of the history and natural causes of extinction, and the beginning of the second part, where Kolbert begins addressing humans and, specifically, the problems that humans bring to the environment: pollution. Here, Kolbert begins to explain why human actions are significant, how they affect the world, and how they are relevant today.

In the seventh chapter of The Sixth Extinction, Elizabeth Kolbert travels to the Great Barrier Reef off the coast of Australia. To explore the adverse effect of human fossil fuels, specifically carbon dioxide on marine wildlife, Kolbert dives into the history of the Great Barrier Reef, from when it was first explored by Captain James Cook to Darwin’s writings on the reefs to the modern day, where now scientists believe that the reefs “will be the first major ecosystem in the modern era to become ecologically extinct,” a direct result of ocean acidification, which is the ocean’s uptake of carbon dioxide from the atmosphere after prolonged exposure (130). For a moment, Kolbert basks in the beauty and diversity of the coral reef: she sees a variety of sea creatures and understands “what it must have been like for an explorer like Cook to arrive at such a place” (135). However, then she begins to delve into the horrible effects of CO2 on coral reefs, citing evidence from various experiments and researchers, including research from Biosphere 2 and other scientists. She shows just how detrimental human waste and ocean acidification is, and how every piece of human waste directly affects the earth’s marine environments.

The last chapter of her book, Kolbert visits the San Diego Zoo to examine its Frozen Zoo, a storage system containing almost a thousand different species frozen in nitrogen. As she looks at the other zoos around the world who have begun to do the same -- the Cincinnati Zoo’s CryoBioBank and England’s Frozen Ark for example -- Kolbert reflects upon the various, human factors that have compelled scientists to freeze such animals: acidification, poaching, global warming, and invasive species. To conclude her novel, Kolbert brings up environmental issues of the past; for example, she references Rachel Carson’s Silent Spring and points out that after its publication, there were some efforts to rescue endangered species. Then Kolbert summarizes her evidence in the novel so far, referencing glaciation, global warming, ocean acidification, and asteroid impacts, which support the causes of extinctions. But then, Kolbert brings up the one factor that was not evident in previous mass extinctions: humans. Kolbert’s sobering conclusion reminds all people that actions have consequences and explores the possibility of a human-caused mass extinction. Moreover, she claims that “by disrupting these systems -- cutting down tropical rainforests, altering the composition of the atmosphere, acidifying the oceans 00 [humans are] putting [their] own survival in danger” (267). After this serious note, Kolbert claims that, even with this situation at hand, humans may possibly be ingenious enough to undo their mistakes, and that there is still hope for the earth’s inhabitants for now.

Style:

The main topic of Kolbert’s book, the sixth mass extinction in Earth’s history, revolves around the notion of human pollution and human waste changing the earth’s environment. Although the first half of her book deals with the past and the natural factors for the previous five extinctions, Kolbert emphasizes the detrimental effects of human industry and human actions on the earth; a number of her investigations involve directly researching the impact of human waste and action on various ecosystems. Kolbert travels to examine the rapid death rate among species such as amphibians, coral reefs, birds, and reptiles in places all around the globe, from Panama to the Mediterranean Sea, in an attempt to identify the results of human action and, in some cases, inaction. The main exigence for Kolbert’s research is the rapid declination of species diversity in the world; she establishes in the first chapter of her book that “many [species] are approaching [rapid extinction] levels… [an] estimated one-third of all reef-building corals, a third of all freshwater mollusks, a third of sharks and rays, a quarter of all mammals” destined for extinction today (17). Kolbert investigates all over the globe to determine whether or not a sixth extinction is actually taking place, detailing her research and her journey in her book The Sixth Extinction.

Although much of the information and many of the topics that Kolbert encounters in her research may be complicated, The Sixth Extinction is written in such a way that no background knowledge of biology, chemistry, or history is needed to understand the book’s contents. From the beginning of The Sixth Extinction, Kolbert writes with simple language, explaining her reasoning and explaining the science behind her work thoroughly. Even when tackling more complicated scenarios, such as the explanation of the chemistry behind ocean acidification, Kolbert avoids being pedantic, ensuring that her work and her book is understandable. She starts from the beginning, defining extinction and its history from the second chapter, and walks through necessary explanations from there. The informal language and often colloquial terms and metaphors -- in one instance, she describes Neanderthal clothing as “look[ing] like leather yoga pants” -- in The Sixth Extinction make Kolbert’s work easy to read and easy to understand, specifically catering to those who may not know anything about extinction or global warming (244).

Because of her colloquial language and thorough explanations, Kolbert aims to educate not only scientists and biologists but also people who may have never concerned themselves with the environment and global warming before. Kolbert, in writing a novel that is easy to read for most, writes so that the pertinent issue of human pollution and human effects on the environment will be understood by anyone who reads her work. She covers only the fundamentals of extinction and global warming; her book does not cater to those who want to learn more about extinction, but rather those who do not know anything about extinction. Kolbert reports on all of the relevant topics relating to extinction: the background, history, and definition of extinction, and the signs and factors of extinction today, specifically where human factors affect extinction rates. By bringing in samples and evidence, Kolbert supports her claim that humans are destroying their resources and the fragile ecosystems of the earth; she explores the possibilities of the world being in the beginnings of a sixth extinction, and warns of the dangers of continuing to treat the world the way it is currently being treated, imparting a somber message at the conclusion of The Sixth Extinction.

A majority of Kolbert’s book is based upon reasoning. She provides many facts and much evidence on the history of extinction, first defining extinction, then exploring the factors behind extinction -- both manmade and naturalistic. Then, Kolbert, in the second half of her book, travels the globe to personally investigate such factors; she discovers more evidence for the death of many species, the impetus behind which is the same factors that Kolbert detailed in the first half of The Sixth Extinction, when she defined extinction and its historical causes. After identifying causes of global warming and species declination in the modern day, Kolbert investigates these causes even further, identifying their source: humans. The entirety of Kolbert’s book is a progression: she begins with a foundation based on the explanation of extinction, and then gathers evidence -- some evidence from her personal investigations and other evidence from research -- to support the fact that there is a sixth extinction that the earth is in at this very moment. Her carefully-placed chapters follow a logical progression from the history of mass extinctions to extinction today; and her reasoning provides support and evidence for her final conclusion: that humans, through their pollution and overfishing and other destructive tendencies, are causing the sixth mass extinction.

In addition to her reasoning, Kolbert often employs pathos to highlight the gravity of the situation. To begin her book, Kolbert details the loss and potential loss of diversity that the earth faces and may face; she describes the animals, plants, and other creatures that may die off as a result of an extinction. As she explores the world, Kolbert often describes the places that she visits as well. In particular, she narrates the beauty and the diversity of many ecosystems around her -- such as the Great Barrier Reef, Panama’s rainforest, and European birds -- to evoke a sense of awe in some people who, if they have not seen such sights, will feel a desire to see this diversity and feel a desire to help stop the extinction, and other people who, if they have seen such sights, will understand Kolbert’s fascination with extinction and the diversity of life and also feel compelled to help stop the sixth extinction. By describing wildlife beauty, Kolbert shows what wonderful life would be lost if the sixth extinction takes place. Additionally, in the final chapters of The Sixth Extinction, Kolbert addresses her readers as citizens of this earth; she claims that “since the start of the industrial revolution, humans have burned through enough fossil fuels… to add some 365 billion metric tons of carbon to the atmosphere,” propelling her audience to believe that human actions directly impact the world (113). As people who live on Earth, Kolbert’s readers’ civic responsibility makes them concerned for the life and diversity in their environment. And, as Kolbert finishes her book with a very clear warning, fear instilled in Kolbert’s readers will most likely push them to take action and help fight against the sixth extinction.

Kolbert employs an informal style of writing, often drawing from a colloquial vocabulary, and establishes a narrative type of book. Although she defines many subjects and explores history throughout her book, Kolbert maintains a sense of storytelling throughout her novel. Kolbert’s readers follow her on her trek around the globe; often times, Kolbert adds unnecessary information to make her work less formal and less scientific. As she explores the Amazon, Kolbert describes her “lunch and purchase[s]... includ[ing] bread and cheese and a shopping bag’s worth of coca leaves… bought for the equivalent of about two dollars” (149). These subtle details make Kolbert’s book resemble more of a story than an informative piece, and also make her book much easier to read. While she divulges information, Kolbert also adds her own, sometimes humorous, observations: she describes the food that she eats and the people she meets, sometimes describing the animals she encounters in an informal fashion -- Kolbert meets a rhino, Suci, and views “her prodigious backside” (217). These interjections and casual observations, along with Kolbert’s facts and research, balance out her book and make The Sixth Extinction a much lighter read.

Delivery:

The Sixth Extinction has a subdued yellow cover, with an image of a mastodon skeleton -- fit with two enormous tusks and a long tail -- on its side running across the front page. The mastodon’s tusks are so large they cover a few letters in the title, emphasizing the enormity of the skeleton. The fact that the mastodon is turned on its side makes it seem as though the image were in a fossil catalogue; the image is there not for aesthetic purposes but for scientific research purposes. However, in juxtaposition to the arrangement of the mastodon skeleton, the colors of the book are vibrant: the large navy-blue text of the title and subtitle is sharply contrasted against the dark yellow background and the red-tinged skeleton of the mastodon. Even though the arrangement of the mastodon makes The Sixth Extinction seem like a scientific book, the vibrant colors of the covers add personality to the book, correctly representing the book’s content: scientific, informative research told in a descriptive, narrative way.

        

Inside the book, the text is larger than usual, Times New Roman, widely spaced. Within each chapter are several sections marked off by a blank line between chunks of text, effectively making The Sixth Extinction’s text seem inviting. Rather than small pages of cramped text, The Sixth Extinction looks more like a novel, its large pages and large fonts inviting. Each chapter has the scientific name of its species underneath it in italics. The first line of every new chapter is printed distinctively in all capital letters.

          

The entire text is interspersed with black and white photos from Kolbert’s travels or photos or sketches or charts that explain some of Kolbert’s definitions. There is a black-and-white photo in at least every other chapter, breaking up the monotonous text and clarifying concepts that Kolbert details in her writing; the photos make Kolbert’s book much easier to read.

Kolbert often references outside sources. As she travels across the globe, researching factors that contribute to the sixth extinction, she meets a variety of scientists and researchers. She names all of these scientists -- researchers from America, graduate students from Peru, Australian marine biologists -- and often introduces them as people, rather than sources; she introduces a British marine biologists as having “dirty blond hair that sticks up in unpredictable directions” and an Italian one as having “reddish brown hair that reaches her shoulders” (112). Already Kolbert establishes a familiarity with her sources, integrating them into her story rather than citing them at the end of her book. By incorporating these sources, people, and information into her book in this manner, Kolbert maintains a sense of narration in her book, and The Sixth Extinction reads as a story rather than a scientific piece of writing. The people that Kolbert does reference in her book are all accomplished, credible researchers or scientists. Kolbert either describes her sources’ education or their actions, revealing their expertise and their experience in their fields.

For sources she did not personally meet with, Kolbert adds fifteen pages worth of notes at the end of The Sixth Extinction, where she cites various novels, magazines, and other scientific journals. In addition to those notes, Kolbert adds six pages of a selected bibliography, MLA format, in the back of her book. After her bibliography, Kolbert cites her photos and their sources as well.

Memory:

Kolbert blends science and narrative together in her book The Sixth Extinction. When I first began reading, I expected the book to read like many texts of scientific work. However, Kolbert maintains a light tone throughout her book, adding subtle details -- such as the meal offered at a university or the temperature of the Mediterranean the day she visited -- that make The Sixth Extinction seem more of a narration than an informative text. And throughout her book, Kolbert intersperses some humorous interjections or comments. Additionally, Kolbert crafts metaphors with colloquial language to make concepts easier to understand: she describes putting on a dry suit as “preparing for a space journey” (112).

Kolbert outlines her journey across the globe, detailing her visits to various places, but adds information, history, and background to each location. She crafts a story out of the thirteen species she follows, beginning with Panamanian frogs and ending with humans. With each progressive chapter, she moves from the background of extinctions -- their history and their definition -- through the various extinctions Earth has seen, to the final, sixth extinction, she hypothesizes, occurring now. However, instead of piling on fact upon fact, Kolbert makes sure to add humor and description to balance out her book, making The Sixth Extinction easy to read, like a narrative story, but informative like a scientific research paper.

While the full title of Kolbert’s book is The Sixth Extinction, Kolbert does not actually delve into the aforementioned sixth extinction until the second half of the book. Granted, the first half of The Sixth Extinction offers important background information on the history and development of extinctions; but I expected more exploration of the actual sixth extinction. She does mention CO2 emissions and human pollution as causes to the sixth extinction, but I expected her to explore more solutions to this sixth extinction. She finishes her final chapter on a vague, but hopeful, note, explaining that possibly some kind of “human ingenuity [might] outrun any disaster human ingenuity sets in motion” (268). She jokes that, if all else fails, humans can “decamp to other planets;” this comment seems to contradict her otherwise somber conclusion (268). And often enough, Kolbert does seem to force humor into situations that otherwise do not require humor; her attempts to keep the book light and informal sometimes come off as forced and affected.

           

However, despite its flaws, The Sixth Extinction would be a commendable recommendation to anyone interested in the science behind global warming and extinction. Firstly because Kolbert manages to combine elements of both narratives and scientific writing into one book to make the read more interesting and more manageable, and also because Kolbert writes in such a way that anyone will be able to read The Sixth Extinction. Kolbert goes through a history of extinction, evolutionary theories, and other concepts needed to understand her novel before delving into her evidence for the sixth extinction. Additionally, while there are some complex scientific concepts, Kolbert explains them thoroughly and simply, so one can understand them even without background knowledge in chemistry or biology. Moreover, the subject matter of The Sixth Extinction is relevant to everyone. It is an issue that is ongoing, and will not stop. The Sixth Extinction deals with an issue that applies everyone on Earth, and affects anyone who lives on the planet. Kolbert employs pathos in her book to appeal to the reader’s sense of civic duty, and it is our duty, as people who live on earth, to be knowledgeable about our actions and to take care of the world around us.

          

After finishing The Sixth Extinction, I learned many things. Kolbert walked me through the beginnings of the definition of extinction, thanks to the work of George Cuvier and his discovery of mastodon teeth -- the mastodon skeleton is the image on The Sixth Extinction’s front cover -- and several others. After that, Kolbert explains several theories of evolution from Lyell to Darwin, all while exploring the reasons behind the rapid death of amphibians, the extinction of the great auk, and the mastodon. From there, I learned several factors that contribute to extinction, from asteroids crashing into the earth to ocean acidification and acid rain to invasive species. In addition to facts and statistics regarding extinction, Kolbert employs many other scientific ideas and historical facts to tell her story as well: she explains how human DNA varies from Neanderthal DNA and writes about Icelandic hunters shooting down the last wild auk.

           

Although the way Kolbert combines narrative and scientific writing is fascinating, and although learning about golden frogs and the Great Barrier Reef is intriguing, the main subject of Kolbert’s book is the name of the title: the sixth extinction. Kolbert researches a time-sensitive, pressing issue that directly involves all people today; she warns the world of what may happen -- the death of a number of species, including humans. The subject of her book affects everyone who reads it and is significant both inside and outside the scientific community today. In a literary perspective, Kolbert’s book fits into a newer genre of narrative nonfiction, not unlike Truman Capote’s In Cold Blood and Dave Cullen’s Columbine. Kolbert researches her material and presents her story in a narrative fashion, but emphasizes the importance and significance of her issue all the while.