Chapter 1 What Is Evolution?
In Coyne’s Why Evolution Is True (2009), the debate between the theories of creationism and evolution is introduced. The two theories take vastly different approaches to explain how and why the world is full of the many variations of plants, animals, insects, reptiles, and human beings. The theory of creationism explains these things by intelligent design. This is where divine intervention takes place and an almighty, omnipotent god creates all beings, all of a sudden, with all of the variations needed to survive in the environment that they currently live. There is no macroevolution, only slight adaptations of the beings to their environment. The text quotes William Paley, and 18th century English philosopher who stated that “the existence of well-adapted organisms and their intricate features surely implied a conscious, celestial designer-God” (Coyne, 2009, p.2). However, after reviewing all of the evidence presented for evolution, the theory of evolution explains many more things. The theory of evolution explains the variations by stating that “species undergo genetic change over time” but it does not predict if or how fast a species will change (Coyne, 2009, 4). Charles Darwin took the theory of evolution, applied facts and data and, by introducing natural selection, explained when and how these changes in species’ occurred. Evolution, or Darwinism, included six components: evolution, gradualism, speciation, common ancestry, natural selection, and non-selective mechanisms (Coyne, 2009, p.3-13). After evolution, gradualism explained how substantial changes in a species took hundreds, thousands, or millions of generations to evolve. Also, the pace of evolution is not necessarily constant. Speciation explains how different groups that cannot interbreed or exchange genes come about. Common ancestry explains how every species shares a common (or cousin) ancestor at some point in the past. Natural selection rejects the notion of involvement from supernatural forces but asserts that genes mutate based on the species’ ability to survive and reproduce in a given environment. Lastly, there are non-selective mechanisms that affect evolution but the main idea is that evolution does not necessarily cause new features to spring up but allows mutations in traits that already exist.
Chapter 2 Written in the Rocks
The fossil record is the best, historical proof for the theory of evolution (Coyne, 2009, p.21). Without the fossil record, the text asserts that all humans would have as evidence of evolution are the “similarities in form, development, and DNA sequences” (Coyne, 2009, p.22). As fossils are put in chronological order and rocks within the strata that the fossils are found are dated, a timeframe of when the creature lived can be assigned. Also, after studying the fossils, conjectures were formed regarding how the species lived. When fossils that shared similar traits are located in certain time periods, then the theory of evolution has evidence to support its tenet of gradualism and speciation. Although the fossil record is incomplete being that there is fossil evidence for only .1%-1% of all species (Coyne, 2009, p.23), there are more fossils being discovered that add to the clarity the fossil record provides. Since the fossil record does not document every transition in the evolutionary cycle, the fossil record does show that early life began as simple organisms and then “got more complex after time” (Coyne, 2009, p.26). The fossil record is proof of common ancestors and transitional species, and predicts the mixture of traits that can be found in the species of a particular era (Coyne, 2009, p.37-38). The fossil record accomplishes three things through its well documented findings. It is a testimony to evolution, predicts transitional forms and the timeline they can be found in, and promotes the concept that existing features are ‘remodeled’ into new ones.
Chapter 3 Remnants: Vestiges, Embryos, and Bad Design
Vestigial traits can only be explained by evolution. Intelligent design is not the best explanation for why these traits still exist. If organisms were designed supernaturally, it does not make sense to design them with physical traits that are useless or not utilized in the manner for which they were originally designed (Coyne, 2009, p.60). Those traits, or atavisms, make a great argument for evolution since it makes more sense that, based off of time and location, vestigial traits actually evolved to their current state and were repurposed for the species based on what assisted with survival and reproduction within their specific geographic location. Vestigial organs and traits are “exactly what we’d expect to find if natural selection gradually eliminated useless features or refashioned them” (Coyne, 2009, p.68). Vestigial traits and atavisms can occur as a re-expression of genes that were once useful for their ancestors. Human tails are an example of a vestigial trait since they are useless for the species but may have once been for the ancestors (Coyne, 2009, p.70). Evolutionary processes will inactivate genes that are no longer useful in the survival and reproduction of the species instead of removing them. That is why, in some instances, these genes can be reactivated by scientific or natural processes and be expressed in the form of organs or appendages that are not useful to the current design of the species. The theory of creationism, based off of the argument of intelligent design, does not explain why organisms are suddenly created with imperfect features and traits. Evolution is the more practical explanation and, as evidenced by the gradual changes documented in the fossil record, has evidence to substantiate the claim.
Chapter 4 The Geography of Life
Adaptation and speciation occur through evolutionary processes based, in part, to geographical location. A similar organism or species will develop variation based on the best survival and reproduction genes suitable for the region it is located. There are some isolated regions of the world that are home to endemic plants and animals (Coyne, 2009, p .95). Although endemic, these species are not native to the region. There has to be an explanation for how these plants and animals developed, shifted location, and are now only found in the regions they are currently located in. Coyne (2009) asserts that biogeographic evidence is powerful for evolution and does not support creationism (p.95). Different locations with similar terrain and climate are home to vastly different species. With creationism, for survival and reproductive benefits, if characteristics regarding the environment are the same minus the geographic location, evidence should be found to support the reason that species’ are so different. However, that is not the case. Coyne (2009) credits continental drift and molecular taxonomy (p.97) as providing the best explanation regarding how the earth shifted and what effect that had on species located in different regions, even with similar terrain and climate. Creationists have not provided a suitable explanation why “different types of animals have similar forms in different places” (Coyne, 2009, p.101). Evolution better explains how placental mammals and marsupials can have similar features and, yet, are two different species. If the traits they share assist them with survival in their geographic regions, then they will exhibit those traits yet still possess characteristics in form and genes from their respective ancestors. The pace at which these adaptive qualities evolve is not consistent as there may be selective processes that increase or decrease that rate, such as colonization (Coyne, 2009, p.152). It does not matter what lineage the plant or animal came from as long as the adaptations they undergo are suitable for their current geographical location.
Chapter 5 The Engine of Evolution
Variations within and between species occur to help a species with its predatory endeavors while assisting other species to develop intense defense mechanisms. Again, for survival and reproductive purposes, adaptations evolve which allow species’ to change in “appearance, behavior, and structure” (Coyne, 2009, p.122) and can encourage many variations from “pseudo-copulating” of plants to ensure pollination to parasitic behavior to ensure reproduction and food supply (p.123-124). While creationism attempts to explain the variations by promoting the celestial design doctrine, the theory of evolution offered the “notion of a mindless, mechanistic process—natural selection—that could accomplish the same result” (p.126). The process of natural selection is supported by much observable and documented evidence in that species do not produce conscious effort to adapt to their environments. They only proceed with business as usual, which involves obtaining food, shelter, protecting themselves and their domain, and reproducing. The environments they reside in will naturally select the adaptations exhibited that allow for the best chances of survival and reproduction. The genes that are expressed by the adaptations will naturally be selected and be passed on to the next generation of offspring (Coyne, 2009, p.127). “Successful” adaptation ensure the highest “reproductive output of it possessor” (p.131) so offspring have that same or higher probability to reproduce and continue to pass on those genes. It is also noted that adaptations can occur without the need for survival or reproduction. Just as any species has some ability to choose its mate, adaptations can occur that do not have anything to do with survival or reproduction. “Domestic,” or “artificial,” selection occurs when breeding takes place. Organisms can be placed together in specific conditions to encourage mating in order to produce offspring with desirable traits. Sometimes, when the breeding occurs, in a lab or otherwise, it can foster “new mutations” that help the organism adapt to a new environment (Coyne, 2009, 140). However, the new adaptations are not emergent. They are modified from pre-existing features (p.140).
Chapter 6 How Sex Drives Evolution
Adaptations also evolve to assist a species’ in its reproductive efforts. Sexual dimorphisms (Coyne, 2009, p.159) are the differences in males and females of a species. These differences, some of which assist with attracting mates for reproduction, such as possessing bright colors or unique songs, can attract predators and only are exhibited during particular seasons. Darwin concluded that “if traits differ between males and females of a species, the elaborate behaviors, structures, and ornaments are nearly always restricted to males” (Coyne, 2009, p.161). Obviously, the more a particular feature assists with attracting a mate, more offspring will be born with the gene for that feature. When the roles are reversed and females must compete for male selection, the females of a given species will exhibit the variations needed to attract a mate (p.174). Coyne (2009) also points out that features are adapted to assist with post-mating competition to protect the females after insemination so that offspring is sure to have the most favorable genes for survival (p.164). Since female selection generally drives sexual dimorphism, males of a given species usually possess the most variations. Also, since most species still employ some form of sexual reproduction, as opposed to asexual reproduction, then dimorphisms continues to occur to this day (Coyne, 2009, p.169). Coyne (2009) speculates that females within a species get to choose because reproduction is “expensive” for them and “cheap” for males (170). Males release a lot of sperm while females usually nurture far less than what was expended. Males also inseminate more than one female as there are few species that are monogamous (Coyne, 2009, 172). Natural selection helps in the quest to produce offspring and is based on sexual selection.
Chapter 7 The Origin of Species
Speciation occurs by many natural selection methods. All plants and animals can be placed in their “appropriate” categories, regardless of the cultural and geographic background of the group categorizing them (Coyne, 2009, p.184). A component of speciation is that groups do not interbreed, thus exhibiting reproductive isolation. They do not intermingle the genes that produce certain traits. It is not that members do not possess the capability to breed, but they exhibit “differences in appearance, behavior, or physiologythat prevent them from successfully interbreeding, while members of the same species can interbreed readily (p.187-188). There are many barriers to overcome to interbreed species and, even if those barriers are broken down and reproduction is achieved sexually or synthetically, the offspring will usually be sterile (p. 188). Creationism is not able to adequately explain the type of macroevolution that occurs that prevent similar species from producing offspring. The theory of intelligent design fails to produce enlightenment regarding the reason such differences have arisen instead of simply allowing a lesser number of species to reproduce and ensure offspring, thus longevity. To clarify how speciation can occur, outside factors that influence the gene pool must be taken into account. Coyne (2009) asserts that “most often, adaptation to different “environments” results in mating discrimination between the populations” (p.196). That along with reproductive techniques, such as the pollination of flowers, can influence hybrid tendencies (p.198). Also, there are several types of hybridization that can occur naturally or superficially. By introducing new plants or animals into a specific location, or assisting the unison of their genes in a laboratory, new species can be observed “beginning to arise as populations evolve incipient reproductive barriers” (Coyne, 2009, p.205).
Chapter 8 What About Us?
Humans evolved from a common ancestor of other species also. The “human fossil record comprised only a few bonestoo humanlike to count as a missing link between ourselves and apes” (Coyne, 2009, p. 210). However, with more discoveries of hominid remains, Darwin asserted “that humans had evolved from apelike creaturesin Africa” (Coyne, 2009, p. 211). Human anatomy is placed “in the order (of) primatesmonkeys, apes, and lemurs, all sharing traits such as forward-facing eyes, fingernails, color vision, and opposable thumbs,” along with other traits (p.212). The process of human evolution involved beginning to walk upright instead of horizontally and progressed to include various mental and emotional attributes. Humans’ “upright posture evolved long before” the brain (p.221) as evidenced from the fossil record and, in particular, the discovery of “Lucy” by Donald Johanson and Tom Gray in 1974. While creationism asserts that Man emerged as an intricate expression of intelligent design, the fossil record provides evidence of variations in brain size and development of “teeth, skull, and brain” (p.223) that resembles the appearance and functionality possessed by modern humans. As more and more fossils were discovered, placed in chronological order, and analyzed, the “fossilsstart off ape-like and become more and more like modern humans” (p.227). With many evolutionary pressures working simultaneously or chronologically, humans evolved and have common ancestors that were ape-like in resemblance. DNA analysis shows that humans have high “genetic resemblance to our evolutionary cousins,” the apes. Also, when compared, the DNA sequence of humans and apes displays a “difference at just one out of every one hundred amino acids” (Coyne, 2009, p.230). The issue of how different races surfaced within the evolutionary process and progressed has to do with genetic variations that created adaptations to various geographical locations.
Chapter 9 Evolution Redux
Despite the myriad of evidence available through various disciplines of scientific research, some still do not believe the theory of evolution. Coyne (2009) states that “every fossil that we find, every DNA molecule that we sequence, every organ system that we dissect, supports the idea that species evolved from common ancestors” (p.243). There are still many inconsistencies and controversies associated with the theory of evolution. Despite present evidence, questions and the investigations to answer them remain to be undertaken. Also, while evolution can provide answers to some questions of how humans came about and where they came from, abstract complexities such as morality, religion, temperament, etc. are still being studied. Unfortunately, due to perceived moral evils, some creationists believe that “all of science, is one of naturalistic materialism” (p.244) and will fight theories that do not acquiesce to religious viewpoints. Some extreme conservatives rationalize that by teaching the theory of evolution, people may become naturalistic and materialistic with what they consider their morals and values, which will, supposedly, lead to a meltdown of societal structure. The new discipline of sociobiology seeks to explain the evolution of human behavior and while it is extreme to categorize all human behavior as having an “evolutionary basis”, some behaviors may have evolved while others might just be innate (p.247-248). Humans are still growing and changing physically, emotionally, and mentally in ways that have nothing to do with evolution since it is happening so quickly. Diversity in social norms is definitely another discipline that can, arguably, display Darwinian characteristics yet is not indicative of the adage “survival of the fittest.” Times are rapidly transforming and social values and trends are here one day and gone the next. Simply put, evolution tells us where (humans) came from, not where (humans) can go (p.251).
References
Coyne, Jerry (2009). WHY EVOLUTION IS TRUE. New York, NY: Oxford University Press.
