Scientific Evidence Strongly Supports the Theory of Evolution by Common Descent

Pro 1: Evidence from Our Bodies Our bodies have yielded much evidence as to how life evolved on earth, as Theodosius Dobzhansky once said, “Nothing in Biology Makes Sense Except in the Light of Evolution. ” These words reign true throughout the study of biology and throughout our bodies. Vestigial Structures Definition: “A vestigial character is reduced and rudimentary compared to the same complex structure in other organisms. Vestigial characters can certainly have functions; non-functionality is not a requirement. ”[1] P1: If evolution by common descent were true, we should see such instances of vestigial structures. P2: We see many examples of these structures. C: Therefore, common descent most likely occurred. There are many examples of rudimentary and nonfunctional vestigial characters carried by organisms, and they can help uncover new information in terms of evolutionary history. For example, there are many flightless beetles (i. e. , weevils from the genus Lucanidae, which retain perfectly form wings underneath fused wing covers (image 1-1) [2] and even blind, cave dwelling fish and salamanders with eyelids – albeit no eyes (figure 1-2)! [3] Figure 1-1 Figure 2-1: This Typhlotriton spelaeus is completely blind, yet retains the eyelid and eyes, though they are fused shut. Conclusion There are many vestigial structures than can appear in multiple species. These vestigial structures yield valuable evidence for the Theory of Evolution. Atavisms Definition: The reappearance of a lost character specific to a remote evolutionary ancestor and not observed in the parents or recent ancestors of the organism displaying the atavistic character. These are different from vestigial structures as vestigial structures are found in all or most species whereas atavisms are found in relatively few and rarely show up. [4] P1: If evolution by common descent were true, atavisms should appear. P2: Atavisms do appear. C: Therefore, evolution by common descent most likely occurred. Atavisms also offer powerful and concise evidence for evolution. Atavisms can be quite strange such as a human newborn with a full tail (figure 1-3)[5] Figure 3-1: This is an x-ray of a 6 year old girl. [6] Dolphins have also been known to have been born with extra sets of hind-limbs, most likely originally used for land. See figure 4-1. Figure 4-1: The hind-flippers of a bottlenose dolphin found in Japanese coastal waters. Yellow arrows indicate the location of a well-formed atavistic set of hind limbs. Conclusion Atavisms are very strange should we expect creation to occur. Why would God give a human a tail, or a dolphin with hind limbs? This makes no sense except in the light of evolution. Pro 2: Evidence from the Genome Perhaps the most powerful evidence of common descent comes not from our bodies – but from our DNA and from the human genome. Our genome is full of abundant evidence for evolution. Pseudogene Definition: A segment of DNA resembling a gene but lacking a genetic function [7] in other words, it is a segment of DNA that has been disabled. P1: If evolution by common descent occurred, pseudogenes should be observed. P2: There are many such cases of pseudogenes. C: Therefore, evolution most likely occurred. Malaria is one of the most horrific human diseases. However, at one point in our evolutionary history, humans enjoyed immunity to malaria. What happened for humans to gain and lose resistance to malaria? Malaria is caused by a microorganism known as Plasmodium falciparum. It cannot be transmitted from person to person but must be carried via a mosquitoes and acquired and transmitted when a mosquito bites a person. Chimpanzees suffer from a less severe form of malaria caused by a microorganism called Plasmodium reichenowi. What happened is the following: The human parasite evolved from the chimp parasite by jumping hosts from humans to chimpanzees. Plasmodium reichenowi recognizes a substance on a gene called CMAH. Our genome carries this gene and we have it in the same strand of DNA as chimpanzees do. However, the only difference is it is disabled – a pseudogene if you will. No-one has the original non-mutated version. The mutation that disabled the CMAH gene had a distinct advantage of those that did not – they became resistant to malaria. [8] So, what happened? Why did we lose our resistance to malaria? The answer lies in the evolution of malaria itself. Mutations in a gene called EBA-175 allowed those parasites that carried the same mutation to recognize another substance which is abundant on human red blood cells about five to ten thousand years ago. The results: Plasmodium falciparum evolved as a new species. We are highly susceptible to this new form of malaria and the new version of malaria is much worse than the old one. [9] Pro 3: Evolution in Action Observed Cases of Speciation If evolution by common descent is true, we should be able to observe evolution. We have observed speciation many times thus irrefutably confirming the fact of evolution. Moreover, there have been cases where the documentation of evolution is overwhelmingly strong, we can trace the origin of specific diseases and development of entirely new species. P1: If evolution is true, we should observe speciation. P2: We have observed speciation. C: Therefore, evolution is most likely true. "Three species of wildflowers called goatsbeards were introduced to the United States from Europe shortly after the turn of the century. Within a few decades their populations expanded and began to encounter one another in the American West. Whenever mixed populations occurred, the specied interbred (hybridizing) producing sterile hybrid offspring. Suddenly, in the late forties two new species of goatsbeard appeared near Pullman, Washington. Although the new species were similar in appearance to the hybrids, they produced fertile offspring. The evolutionary process had created a separate species that could reproduce but not mate with the goatsbeard plants from which it had evolved. "[10] There are many other cases of this; however with space running out I will use this one example. This is so powerful that creationists themselves have even admitted that speciation has occurred on Earth. As CMI admitted, “new species have been observed to form”[11] Conclusion The Theory of Evolution is powerful – it has made numerous predictions that have been confirmed and more evidence is uncovered every day. If I had more room (and I’ll expand in the next round), I would show how we can actually make our knowledge of evolution relevant in our lives. Onto con. [1] . http://www.talkorigins.org... [2] Coyne, J. “Why Evolution is True. ” [3] Ibid. [4] Fairbanks, D. “Evolving: The Human Effect and why it Matters. ” [5] Humans have been known to have been born with fully functional tails – with even muscles to voluntarily move the tail. See ibid for more information. [6] See . http://www.ncbi.nlm.nih.gov... [7] . http://medical-dictionary.thefreedictionary.com... [8] Neanderthals apparently had this same CMAH pseudogene meaning that the disabling mutation occurred before the splitting of the two lineages [9] Fairbanks, D. “Evolving. ” [10] . http://www.talkorigins.org... [11] . http://creation.com...