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Evolution is the process that involves the change in organisms over a period of time as a result of changes in hereditable, physical or behavioral characters. The truth behind Evolution emphasizes the solid pieces of evidence that verifies mostly evolution natural selection to be a fact. Putting together and explaining the latest ideas and discoveries from many disparate areas of the modernized science Jerry A. Coyne leaves us with an open mind in his book of why evolution is true in any doubt about the truth and the beauty of evolution.

Chapter One: What is Evolution

Learning models in the evolution theories include various theories that explain more about the evolution and existence of many living things on the planet earth. These theories include cell theories, relativity theory, evolution theory (Winther, 2015), the theory of plate tectonics and atomic theory. Evolution shows us more about us in the whole extraordinary and the great array of life. It brings us together with every living thing in the earth today and with long-dead creatures and myriads whereby it provides us with the true accounts of our origins hence replacing thousands of year’s myths that existed and satisfied us.

According to Darwin’s theory of Evolution, it states that the whole of life was as a result of evolution (Winther, 2015). The operation was then later driven by Natural selection which happens to be the most valid theory supported by evidence from a wide variety of scientific fields like geology, genetics, paleontology, and developmental scientists and it’s sometimes described as the survival of the fittest. However, it is equally thought to erode morality.

Various shreds of evidence have been found that supports the evolution theory, for instance, the study on human evolution that involved a study on 1,900 students published online in the month of October 2017 in the journal Personality and individual differences found that many people may have a problem in finding a mate because of the rapidly changing social technological advances that are faster growing than human whereby one or two individuals face considerable difficulties when mating (Winther, 2015). Also, the story of the origin of whales is one of Darwin’s most evolution that is fascinating and the best examples scientists have in selection hence that’s a conclusion as to why evolution is true.

Chapter Two: Written in the Rocks

Fossils are known to be the original unchanged remains of plants and animals. Its formation begins when an organism falls into soft sediments like mud. All living organisms are considered to have an equal ratio of carbon 12 and carbon 14. When one dies, it ceases decay to replenish carbon into its tissues and the decay of carbon 14 to nitrogen 14 changes the ratio of carbon 12 to carbon 14. The radioactive isotope half-life describes the amount of time that takes half of the isotope in a sample to decay. In radiocarbon dating, carbon 14 half-life is 5,730 years. Hence when finding the age of an organic organism, the half-life of carbon 14 as well as the rate of decay which is -0.693 is considered.

Grand Canyon has an amazing variety of rock foundations with lots of fossils concealed within. The sedimentary rocks exposed on the canyon are rich with marine fossils such as brachiopods, crinoids, and sponges with some layers containing terrestrial fossils such as leaf and dragonfly wing impressions, footprints of scorpions, centipedes, and reptiles (Zwinger, 2015). Due to the lack of a complete record of fossil, telling the exact rate and divergence is made difficult (Allmon & Yacobucci, 2016). Lack of a clear link makes it hard to conclude a direct link between the ancestors.

Tiktaalik roseae also referred to as fishapod is a fossil fish dating 375 million years which was found in 2004 in the Canadian Arctic (Gordon, 2015). Being a mixture of both fish and having amphibian traits, it is considered to be interesting. The fish resembles a cross between the primitive fish and the initial four-legged animals.

Various hypotheses have been suggested for where birds, as well as their feathers, originated. However, that remains largely unknown due to incomplete fossil record the structures and lack of connection to a historical event. Functional speculation regarding the origin of feathers usually focuses on three possible alternatives which are flight, thermal insulation or display. According to Brusatte et al., (2015), recent fossil finds of Late Cretaceous feathered dinosaurs in China have demonstrated that feathers appear to have originated in taxa that retained a significant number of primitive nonavian features. Current evidence strongly suggests even if the most primitive known feathers are found on non-flying animals, birds are theropod dinosaurs. As the earliest function of feathers was probably not for aerial locomotion, it may be speculated that the transitional animals represented by the Chinese fossils possessed skin with the tensile properties of reptiles and combined it with the apomorphic characteristics of feathers.

Chapter Three: Remnants: Vestiges, Embryos and Bad Design

This chapter points out features in the anatomy of different animals that heavily imply the occurrence of an evolutionary change happening in the millions of years preceding its existence and following the existence of the organism’s ancestors.

To begin with, the chapter explores the structures and reasons for the existence of vestigial structures in humans, horses, and ostriches. Vestiges have been defined as “a feature of a species that was an adaptation in its ancestors, but that has lost its usefulness completely or, as in the ostrich, has been co-opted for new uses” (Coyne, p. 61). The most known vestigial structure in humans is the appendix and the vestigial tail called the coccyx “that’s made of fused vertebrae hanging below our pelvis” (Coyne, p. 65-66). The chapter also explores atavisms which are feature developed as a result of remnants of evolution i.e. vestiges, being sporadically expressed during development i.e., when the coccyx develops into a tail in humans.

Embryonic development was also largely explored as a big indicator of the existence of evolution. Take for instance the embryo of a human which first begins with a fish-like structure, then to that of an amphibian, to a reptile and finally to a mammal. This matches the order of evolution of humans and the same is the case for other organisms and their orders of evolution. It has also been argued that the existence of the imperfect design of the anatomy of animals provides a good case for the existence of evolution. Designs such as the location of the gap that the egg needs to jump across the fallopian tube from the ovary to the uterus, and the recurrent laryngeal nerve of mammals covering way more distance from the brain to the larynx than it needs to and making more prone to injury. This is because the imperfect design is precisely what we would expect from evolution (Coyne, p.86).

Chapter Four: The Geography of Life

This chapter explores evolution using a different perspective that involves biogeographical evidence, the theory of convergent evolution, the dispersion of species i.e. the marsupials, the biological composition of island-based animals when compared to those based on land.

The biographic evidence in this chapter explores the effects of dispersion, the evolution of organisms and the Earth over time. The knowledge being used now can be attributed to those developments of continental drift and molecular taxonomy. Using the molecular clock, we can match the evolutionary relationships between species with the known movements of the continents (Coyne, p.97). The theory of convergent evolution was also introduced. It explains why “species living in similar habitats will experience similar selection pressures from their environment, so they may evolve similar adaptations or converge, coming to look and behave very much alike even though they are unrelated” (Coyne, p.101). Instances of this phenomenon can be seen in the white coat of polar bears and snowy owls. This theory illustrates “three parts of the evolutionary theory: common ancestry, speciation, and natural selection” (Coyne, p.101).

The existence of marsupials in Australia illustrates a different part of the evolutionary tale since we need to understand that marsupials traveled to Australia through Antarctica when South America, Antarctica, Africa, and Australia were still joined together to form the supercontinent Gondwana. Evidence of this movement was found in Seymour Island off the Antarctica Peninsula, dated at precisely the right period of time (Coyne, p.102). This tale, together with that of the continental drift also explains the existence of Glossopteris fossil trees and the direction of glacial striations on the underlying rock on the South American, South African and Australian coasts. Lastly, the chapter explores the difference in bio-geographical compositions between oceanic and continental islands which are a result of differences in their formation to prove the solidity of the evolution theory (Coyne, p.108).

Chapter Five: The Engine of Evolution

This chapter focuses on the process of natural selection, how it happens and exactly why it happens. Coyne states that there are three things involved in making an adaptation by the process of natural selection. The first step involves the starting population is variable. He makes the example of mice who exhibit some difference in their coat colors, for instance, there are white-coated and dark coated mice. The second step necessitates that a major proportion of any variation that would occur to result from gene variation, that is, it needs to have a genetic basis, otherwise, referred to as heritability so that the variation can be transferred to the following generation and not die out. This genetic variation may result in mutations that have been defined as “accidental changes in the sequence of DNA that usually occur as errors when the molecule is copied during cell division and may occur regardless of whether they would be useful to the individual” (Coyne p. 128). The third step requires a genetic variation to improve an individual’s probability of leaving offspring (Coyne, p. 129).

The chapter goes forward to explain selection as a combination of randomness and lawfulness (Coyne, p. 129). The process of selection consists of two processes. The first process is that of ‘random’ occurrence of variations and mutations in the genome leading to genetic variations, while the second process is that of natural selection which orders a particular variation and thus picks out the good and dispensing with the bad. So, in a way, the evolutionary process is both random and not random as a result of both of these processes.

There are conditions, however, that will require an ‘adaptive’ feature to evolve through the process of natural selection. One of these conditions is that the feature must result in raising fitness i.e. the average number of offspring, of its possessor (Coyne, p.131).

Chapter Six: How Sex Drives Evolution

This chapter of the book focuses on the connection between sex and evolution. By sex, we mean the attraction between the male and female, a phenomenon that occurs in almost all the species on earth. The author approaches this topic by looking at the peacock, and to be particular, the male species. According to a letter written by Charles Darwin, he laid down his frustration with the idea of animals having features that have proven to be detrimental to their existence. The anatomy of the peacock was his major frustration. Take for instance the peacock, “with his iridescent blue-green tail, studded with eyespots, fanned out in full glory behind a shiny blue body”, it has features that are maladaptive to his long-term survival (Coyne, 2009). As a result of the long tail, it cannot fly, the sparkling colors attract marauders and it spends lots of energy by using its tail to strike. Animals like the renowned Irish elk and the túngara frogs down in Central America also possess such maladaptive features that inspired the research into the theory of sexual selection.

The theory of sexual selection results from the existence of sexual dimorphisms. Sexual dimorphism is a phenomenon where there are traits that differ between males and females of a species (Coyne, 2009). These differences may show in different parts of the animal’s body such as vocal capabilities, tail design and body-color (Coyne, 2009). These features are then used by sexual selection to simply select individuals that have a greater chance of getting a mate. This theory is based on the idea that some animals prioritize the necessity of procreation. As a result of the need to increase the chances of one’s own procreation, which is also viewed as a means of survival, the males develop features that would increase their levels of attraction in the eyes of the female sex. This selection can occur in two forms. One is through direct competition between males for access to females and secondly, is through females’ choosiness among possible mates (Coyne, 2009).

Chapter Seven: The Origin of Species

The chapter on the origin of species is introduced by taking a look at the work of a young German zoologist named Ernst Mayr, who later wrote a classic titled Animal Species and Evolution after having jungles and mountains in the wilds of Dutch New Guinea to collect plants and animals (Coyne, 2009). Ernst is credited for the finding that there are discontinuities in nature that are so clear that this finding has become an objective fact. The discontinuity of nature is what led to a gap in research and in the end, a. Charles Darwin failed to answer the question as to how evolution can produce groups of animals and plants that are discrete and discontinuous, separated from others by gaps in appearance and behavior and how these groups arose from the problem of speciation (Coyne, 2009).

The problem of speciation was in fact not seriously addressed until the mid-1930s.

Ernst Mayr and the Russian geneticist Theodosius Dobzhansky were the first to realize the idea of gene pools that connect the genetic DNA of different classes of species to each other. In 1942 Mayr developed an explanation of species that has become the gold standard for evolutionary biology (Coyne, 2009). Using the reproductive standard for species status, Mayr explained a species as a cluster of interbreeding natural populations that are reproductively isolated from other such clusters. This definition is known as the biological species concept, or BSC (Coyne, 2009).

According to the BSC, a species is a reproductive community—a gene pool, this means that a species is also an evolutionary community (Coyne, 2006).

Chapter Eight: What About Us?

This chapter explores the origin of human beings and our relations with our ancestors. It highlights the paths taken from Darwin’s theories on evolution to Raymond Dart’s discovery of one of the most significant fossils of the 1900s.

Ever since Dart’s period, paleoanthropologists, geneticists, and molecular biologists have used fossils and DNA sequences to determine our place in the line of evolution (Coyne, 2009). We are apes stemmed from other apes, and our nearest cousin is the chimpanzee, whose ancestors diverged from our own some million years ago in Africa. These are irrefutable facts. And instead of fading our humanity, they should produce satisfaction and wonder, for they connect us to all organisms, the living and the dead (Coyne, 2009).

In 1871, the human fossil record constituted only a few bones of the late-appearing Neanderthals—too humanlike to count as a missing link between ourselves and apes (Coyne, 2009). They were considered instead as a deviant population of Homo sapiens.

“Humanness” genes have become almost a Holy Grail of evolutionary biology, with many laboratories engaged in the search (Coyne, 2009). The first effort to discover them was done in 1975 by Mary-Claire King and Allan Wilson, at the University of California. Their findings were astonishing. Watching at protein sequences retrieved from humans and chimpanzees, they realized that they varied on average by only about 1 percent (Coyne, 2009).

The existence of diverse races in humans illustrates that our populations were geographically separated long enough to allow some genetic divergence to occur (Coyne, 2009). Direct genetic evidence, amassed over the last three decades, demonstrates that solely about 10 to 15 percent of all genetic discrepancy in humans is signified by alterations between “races” that are recognized by alteration in physical appearance. The remainder of the genetic variation, 85 to 90 percent, occurs among individuals within races (Coyne, 2009).

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