“Why Evolution Is True” was a very compelling book. It’s arguments and explanation of facts and predictions really helps drive the point of the title of the book. Even before the book begins the author explains that a book like this needs collaboration because the fields needed for this subject can be as diverse as paleontology, molecular biology, population genetics, biogeography, etc. He makes his point very clear how he feels about Creationists. The quote that really spoke to me was, “You can find religions without creationism, but you never find creationism without religion.
” (Coyne, J. A) This prompted me to look up the definition of a creationist, so I could get the best idea of the type of person he was talking about. According to britannica.com a creationist is, “the belief that the universe and the various forms of life were created by God out of nothing. It is a response to modern evolutionary theory, which explains the emergence and diversity of life without recourse to the doctrine of God or any other divine power.
Mainstream scientists generally reject creationism.” (Britannica, T. E.)
The author also helped set the tone for the book when he went over the court cases about teaching evolution in classrooms and opened my eyes by stating the statistics about how many people in the United States and Turkey favored teaching creationism in a science class. As the definition states above creationism is a religious belief, so teaching that in a science class instead of a religion class seems inappropriate.
In this paper I will be going through each chapter of the book and sharing my critiques, highlighting parts that resonated with me, and mentioning my thoughts about the subject matter and evolution.
In chapter one he goes over quite a bit of information. For example, the six components of the modern theory of evolution: evolution, gradualism, speciation, common ancestry, natural selection, and nonselective mechanisms of evolutionary change. The author’s explanation of speciation really caught my attention. Particularly the example of common ancestry in reptiles. As we’ve learned in the course speciation basically means the evolution of different groups that can’t interbreed. The discussion about the chihuahua and the St. Bernard popped in my head. The book really helped me understand speciation a little better when it went on to explain using the figure of the X and Y species and then boiled it down into, “Speciation doesn’t happen very often. But each time one species splits into two, it doubles the number of opportunities for future speciation, so the number of species can rise exponentially.” (Coyne, J. A)
Another part of this chapter that caught my attention was when he mentioned Carl Linnaeus and his “natural” classification. I looked more into Carl Linnaeus and found that his, “…folio volume of only 11 pages presented a hierarchical classification, or taxonomy, of the three kingdoms of nature: stones, plants, and animals. Each kingdom was subdivided into classes, orders, genera, species, and varieties. This hierarchy of taxonomic ranks replaced traditional systems of biological classification that were based on mutually exclusive divisions, or dichotomies. Linnaeus’s classification system has survived in biology, though additional ranks, such as families, have been added to accommodate growing numbers of species.” (Müller-Wille, S.)
In chapter two the author mentioned Afrovenator Abakensis and Jobaria Tiguidensis which were specimens that have helped rewrite the story of dinosaur evolution. I looked more into them and Afrovenator’s was a cousin to Allosaurus which was a 150 million years old dinosaur that lived in North America. (n.d.). Jobaria Tiguidensis lived about 135 million years ago during the cretaceous period and represented an ancient sauropod lineage that survived and flourished only in Africa during that time. (Team discovers) The author made a compelling point about location being important to evolution by using the example of fossil marsupials only being found in Australia, which is why modern marsupials live there. He then moved on to the fossil record giving an amazing time line example that I wished I used in my discussion post. “If the entire course of evolution were compressed into a single year, the earliest bacteria would appear at the end of March, but we wouldn’t see the first human ancestors until 6 a.m. on December 31. The golden age of Greece, about 500 BC, would occur just thirty seconds before midnight.” (Coyne, J. A)
The author went over many other things in this chapter. Such as transitional species like Tiktaalik roseae and “trees down” or “ground up” scenarios. However, the last thing I want to mention about this chapter is his example of the hippo. Just in that section alone I learned so many new things about an animal I never would have considered to help prove evolution. For example, Hippos mate in the water, and their babies are born and suckle underwater.
In chapter three the author goes over some important points to prove evolution: vestigial characteristics, atavisms, dead genes, and bad design. As we studied in the course, a vestigial characteristic isn’t a functionless characteristic. It’s just no longer performing the function it was evolved for. He goes on to talk about birds with reduced wings from the ostrich to the dodo bird. Making the point that sometimes evolution works out like it did for the ostrich, and others it doesn’t like the dodo bird. He mentions the example of vestigial eyes. Stating that many animals that live in complete darkness is a contributing factor about location and needs to be a part of the evolution process. Lastly, he mentions how it can be shown in humans by example of the appendix. “…appendix is simply the remnant of an organ that was critically important to our leaf-eating ancestors, but of no real value to us.” (Coyne, J. A)
The examples for atavisms that stood out to me was that a horse can be born with extra toes, and a human baby can be born with a tail. It seems like the author makes it a point to start out with an animal example, and then ties into how it relates to humans. He also gives good examples. Such as what atavisms isn’t, “A human born with an extra leg, for example, is not an atavism because none of our ancestors had five limbs.” (Coyne, J. A) The author then hooked me with a theory to the question why do atavisms like this occur at all? “…that they come from the re-expression of genes that were functional in ancestors but were silenced by natural selection when they were no longer needed. Yet these dormant genes can sometimes be reawakened when something goes awry in development.” (Coyne, J. A)
The book goes on to talk about dead genes and pseudogenes. The author explained another compelling logical dispute on creationism with the sequence of i/rGLO in guinea pigs, and primates. He also pointed out another connection between primates and humans by the human genome containing thousands of ancient viruses rendered harmless by mutations that sit in the same location on the chromosomes of chimpanzees. Those examples really showed that dead genes have a real connection to evolution.
The last point I wanted to visit in this chapter was bad design. The section goes through the development life cycle of animals and humans. The author brings up the point that all vertebrates begin development looking like an embryonic fish, then amphibian, then reptile, and finally mammal. He also brings up good points on bad design through the flounder’s eyes starting out on both sides of the head and the shifting to one side. All these facts and examples boiled down to one point, “Imperfect design is the mark of evolution; in fact, it’s precisely what we expect from evolution.” (Coyne, J. A)
Chapter four addresses an important question. If all animals had a common ancestor, then how could they have dispersed so widely? The author explains by looking at different species that live on continents and then at those on islands. By using facts about the biogeographic patterns, Glossopteris trees, etc. the author states that all the continents were once connected in a land mass called Gondwana. After continental drifting over a long period of time these land masses became slightly different habitats, which would explain convergent evolution. As the book stated, “Convergent evolution demonstrates three parts of evolutionary theory working together: common ancestry, speciation, and natural selection.” (Coyne, J. A)
Chapter five’s theme seemed to be selection and adaptation. The chapter started out with highlighting how the local bees in Japan have adapted and evolved to defend themselves against the very hostile local hornets. Also, orchids that have flowers that superficially resemble bees and wasps to help them spread pollen. The author then dives into natural selection giving examples like the adaptation in the color coat of wild mice and citing the experiment by Donald Kaufman. He also adds that mutant forms of genes explain variations in human traits which lead us into genetic drift. Genetic drift is the random change in the frequency of genes over time. Next, the author explained how breeding can cause convergent evolution, and again my head went to the discussion about the chihuahua and the St. Bernard. The author then explains how tests have been done in laboratories to show mutation, adaption, and more proof that evolution is possible. Then he takes it a step farther to explain how a complex system such as blood clotting could be achieved by evolution. “We can’t see the Grand Canyon getting deeper, either, but gazing into that great abyss, with the Colorado River carving away insensibly below, you learn the most important lesson of Darwinism: weak forces operating over long periods of time create large and dramatic change.” (Coyne, J. A)
Chapter six was an in depth look on sexual selection. It raised questions I never even thought about, and then answered them with interesting theories and examples. Such as, I always thought that the songs from birds were solely for matting purposes. However, as the book stated, “Many of the birdsongs that delight our ears are actually threats, warning other males to keep away.” (Coyne, J. A) It really makes you think about sexual selection being a battlefield. Which is probably why biologists call it “law of battle”. This chapter explained why males are usually the ones competing for a mate, and females are the choosier ones. “For males, mating is cheap; for females it’s expensive. For males, a mating costs only a small dose of sperm; for females it costs much more: the production of large, nutrient rich eggs and often a huge expenditure of energy and time.” (Coyne, J. A) It also explained some roll breaking cases like the sea horse, but it still showed that sexual selection is a viable explanation for why animals sometimes evolve traits that give no benefit other than to reproduce.
Chapter seven dove into everything about species. The author first explained that if we want to explain biodiversity then we must do more than explain how new traits came to be. In other words, we must also explain how new species can arise. As I learned from this course and what the book stated, “Mayr defined a species as a group of interbreeding natural populations that are reproductively isolated from other such groups.” (Coyne, J. A) This is called biological species concept. The advantage of the biological species concept is that it takes care of many problems that appearance-based species concepts can’t handle. However, it isn’t perfect because it doesn’t explain things like organisms that are extinct. The author went into other types of speciation that offered their own concepts. For example, geographic speciation, which means there should be reproductive isolation found between a pair of physically isolated populations which increases slowly over time. Sympatric speciation which means a new species would evolve from a surviving ancestral species. However, both continue to inhabit the same geographic region. Allopolyploid speciation, which as the book states, “…is that instead of beginning with isolated populations of the same species, it starts with the hybridization of two different species that live in the same area.” (Coyne, J. A) Finally, Polyploid speciation, which involves changes in chromosome numbers rather than changes in the genes. The author also notes that it’s been estimated that a quarter of all species of flowering plants were formed by polyploidy.
Chapter eight went through information that I know about from this course. For example, the timeline of fossil ancestors, and re-provoked the question about Neanderthals and Homo sapiens. It made me wonder about the theories “multiregional” and “out of Africa”. It also made me wonder about the theories on how we evolved to stand on two legs. “Many biologists feel that these changes in climate and environment had something to do with the first significant hominin trait to evolve: bipedality.” (Coyne, J. A) The genetic and race aspects on human development made logical sense to include sexual selection and cultural environments to predict how each race developed their own traits. The last section “What About Now?” was a bit of an eye opener. It never occurred to me how we’re changing the rules on natural selection to the point where we might be evolving downward. As the author mentioned, I was more curious of things like, “if we were getting smarter and stronger.” However, I did like how he wrapped it up. “…we are evolved mammals—proud and accomplished ones, to be sure, but mammals built by the same processes that transformed every form of life over the past few billion years.” (Coyne, J. A)
Chapter nine seems to be the author’s overall point to his view on Darwinism and evolution. He starts off by listing the topics covered by the book, then tells us Darwinism effects humans just like any other animal. “Darwinism tells us that, like all species, human beings arose from the working of blind, purposeless forces over eons of time.” (Coyne, J. A) He also tackles the question, “does evolution effects our behavior”, and although genes could have something to do with some behaviors I agree with author on his view. “But genes aren’t destiny. One lesson that all geneticists know, but which doesn’t seem to have permeated the consciousness of nonscientists, is that “genetic” does not mean “unchangeable.”” (Coyne, J. A)
I had an opinion about evolution before this course. I knew very little of the actual science behind it, but logically, it made sense to me. “An animal must adapt to its environment to survive. If a disease can mutate then a complex organism should be able to mutate and change. Thus, if a complex organism can change and mutate then it’s very possible that evolution is true.”
I’ve also met people who refuse to believe in evolution. It seemed like no matter how much I argued with the little knowledge I had about the subject they refused to consider any of it. After reading this book I now know that they were the definition of Creationists. I understood the frustration the author conveyed about creationist’s views and arguments. This brought a sense of personal joy while reading the facts, logic, and proof that was covered in this book. This course covered a vast number of topics such as fossil records, biogeography, vestigial structures, etc. I feel as though I have a good foot hold on understanding what evolution is, and I look forward to seeing more discoveries that prove why evolution is true.