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Evolution: Fact or Fiction?

Updated on December 28, 2017
Charles Darwin
Charles Darwin

In 1859, Charles Darwin published the book On the Origin of Species, which outlined the design of living things as the result of random variations and natural selection. Since then, scientists across the globe have continued to research Darwin’s theory of evolution, as they strive to prove that there is fact behind Darwin’s theory. All around the world, these scientists have uncovered various forms of evidence proving evolution. For instance, Lucy, an Australopithecus afarensis uncovered in 1974, is one of the most complete fossils of an early human ancestor. Lucy is one of the fossils identifying the transition from ape to human. Regardless of these facts, some still disregard evolution as hallucinatory due to that lack of human observation of an evolutionary process. Even though evolution has never been observed, life has changed over the billions of years that life on earth has existed, as seen by the similarities between homologies and fossil evidence.


Transitional Fossils

Never seen by the human eye, evolution remains elusive as well as a controversial subject. Although never observed, different fossils have been recovered over the years. The only problem is that “there should be many ‘transitional’ forms that we could observe” in order to draw conclusions as to how evolution works. Even though fossils have been recovered, there is not enough evidence proving that evolution occurred. Transitional fossils prove that through natural selection and adaptations, species evolve, which is why the discovery of the Tiktaalik roseae made such an impact. The Tiktaalik roseae, also known as the “fishapod”, is an essential transitional fossil dating back three hundred seventy-five million years that was discovered in the Canadian Arctic in 2004. The Tiktaalik roseae “looks like a cross between the primitive fish it lived amongst, and the first tetrapods”, which is significant due to the fact that it marks the pivotal transition between fish and species that walked on land. Although more transitional fossils are needed, the Tiktaalik roseae strengthens the evidence towards evolution. Despite the fact that transitional fossils exist, there has never been any direct observation of evolution, leading many to believe that it does not exist. A direct observation of evolution would include a single individual observing the change of a species. According to a professor of anthropology at the University of Pittsburgh, Jeffrey Schwartz, “the formation of a new species, by any mechanism, has never been observed”, which suggests that evolution, even in a controlled experiment, has never been recorded. Admittingly, the creation of a new species has yet to be witnessed, but rapid changes within the same species, such as the peppered moths, may contribute to evidence towards adaptation and evolution. Before the exposure to pollution in the Industrial Revolution in Britain, the species of peppered moths were primarily lighter colored, by after the introduction of smoke and other residues, the habitat where the peppered moths lived became darker, seeing as the trees were covered in smoke. After the shift in environment, the main predator of the moths began to consume the lighter colored moths due to the contrast between them and the trees, however the darker colored moths, who had always had a lower population within the species, suddenly fit into the habitat of smoke and pollution, causing them to survive. The lighter moths began to decrease in number, while “the black peppered moths became far more numerous in urban areas than the pale variety”, meaning that the predators could only see the lighter moths, making the pale moths the minority within the species. Despite the lack of direct observation of evolution, there is evidence that contributes to Darwin’s theory of evolution.

Tiktaalik Fossil
Tiktaalik Fossil

Homologies

Homologies, characteristics shared by two species due to common ancestry, are an example of evidence proving Darwin’s theory of evolution. Homologies occur in three types: morphological homology, ontogenetic homology, and molecular homology. Morphological homology, the anatomical similarities between species, looks at homologous structures in order to prove similarity. Among the most common of morphological homologies are the skeletal components of vertebrates show that different species. For example, the human, cat, whale, and bat, all have similar bone structures in the limb of the creature; the first bone is the Humerus followed by the Radius paired with the Ulna, the next set of bones being the Carpals, then the Metacarpals, and finally the Phalanges. The similarities in the bone structure provide insight as to why “evolution can be considered a process of ‘remodeling’ a population over the course of many generations”. This suggests that over the course of millions of years, natural selection has caused many different species to evolve and develop new traits in order to survive, and henceforth creating a common ancestor from the base of these evolutionary habits. In order to evolve, new variations of a species must be created, and through embryo development, ontogenetic homology has been able to identify similarities of different embryonic structures and development. Studying embryological development can provide evidence of species similarity, and “is one of the most accurate ways to determine whether a structure appearing similar in adult organisms is homologous or analogous”, considering that some physical traits are only present in an embryo, it is easier to tell what species are related. By studying embryological development, different homologies are able to be uncovered. Although ontogenetic homology is accurate, molecular homology, the similarities of species through DNA, RNA, and protein, is the deepest level of homology. The similarities between DNA in different species is strong evidence in itself, and this is because “the very existence in of DNA every living thing on Earth is, in itself, strong evidence of common ancestry [and] it would be highly unlikely for DNA to have evolved independently so many times, over and over”, meaning that the passing down of DNA throughout generations proves through common ancestry that species do evolve. With different methods of homology, it is possible to trace common ancestry and prove Darwin’s theory of evolution.

DNA
DNA

Fossils

Over the course of billions of years, an incalculable number of creatures have lived and died, each leaving behind a record of their existence in the form of fossils. After billions of years, only a fraction of these fossils exist, the majority undiscovered, and from these fossils, clues about these species--growth patterns, the species’ evolutionary pattern, and the history of a species--can be found. By looking at the cellular structure of the recovered fossils, the growth pattern of the organism can be found. Each creature has a particular growth pattern, and by looking at fossils, different indications of growth can be found such as “ growth lines [which] reflect a seasonal pause in the animal's growth”. Findings such as seasonal growth can offer clues as to where the creature lived, the amount of water in the area, and the temperature, especially in plants. Cross-referencing this information with weather patterns of the estimated time frame such as drought may give a more accurate reading of the time period when the organism lived. While observing the cellular structure may provide evidence about that individual fossil, examining the fossil record of an entire species provides indications of the evolutionary pattern of the species. Though there are many gaps, much of the evolutionary timeline has been filled in with billions upon billions of species, each differentiated from the last by “Fossils [which] show how much, or how little, organisms have changed over time”. Fossils are the most accurate evidence of evolution, as they show the transition between species as they adapt and develop. The development of species is documented through fossils, and from this documentation, the history of a species emerges. Throughout a species existence, many changes occur in the makeup of a species such as homo sapiens, or humans, and over time the human species adapted “ [to] walk upright... [to] live in hot, tropical habitats or cold, temperate environments”, and this can be seen through different fossils such as Lucy, who was a Hominidae, which are all species originating after the human/African ape ancestral split. Through the evidence of fossils, it is possible to piece together an evolutionary tree and to recognize where the species evolved from.

As Sir Julian Huxley, a British evolutionary biologist, eugenicist, and internationalist, wrote in the introduction to Darwin’s On the Origin of Species, “Man could no longer be regarded as the Lord of Creation, a being apart from the rest of nature. He was merely the representative of one among many Families of the order Primates in the class Mammalia”. Humans are not the most significant creatures on the surface of the Earth, and regarding this as such only contributes to the ludicrous idea of superiority. Knowing where the human race evolved from not only humbles them but also helps to account for curiosity about why people live they do and where they came from. Evolution has unknowingly affected everything: the way that the world is observed, and how one lives their life. Knowing that humans evolved from apes amongst other things, brings a new outlook on life. Understanding the process of evolution has brought forth advances in medicine; doctors are now able to stay ahead of pathological diseases by understanding the evolutionary patterns of these diseases. Despite never directly observing evolution, Darwin’s theory of evolution has been proven by documentation of similarities of different species through homologies, and the discoveries of various fossils.

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    • Jorge Cruz99 profile image

      Jorge 

      5 months ago from Canada

      Thank you for this educative article. Climate change is forcing the evolution of species to adapt to new conditions. It is yet to be seen if they can make it. Some might not, like California's sequoias, because they have a very long lifespan.

    • K S Lane profile image

      K S Lane 

      6 months ago from Melbourne, Australia

      Nice article. I'm currently about half-way through 'On the Origin of Species' and I figured I'd read up a bit on whether Darwin's theory still holds up to the standards of modern science. Apparently it still does so quite well.

    • Jessie L Watson profile image

      Jessie Watson 

      6 months ago from Wenatchee Washington

      Darwin admitted that fossil evidence was a poor indicator of his theory. To this day, biologists and paleontologists argue over the rate at which species evolved. From a paleontological point of view, it looks as if there are long periods of stasis punctuated by large changes in morphology. Problem is, fossils cannot tell us anything about the softer tissues that decay long before fossilization occurs. Darwin's idea of a gradualism remains consistent with the current biological view of micro-mutations across thousands of years. Granted, environmental stressors and selection pressures do influence how traits are actualized across time. Again, natural selection for the win.

      Good article. Sharp.

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