Scientific Evidence Supports the Theory of Evolution

It is clear my opponent is irratoinal and has no desire to have a rational discussion. A theory is A well supported, conceptual framework that encompasses a large body of scientific facts, inferences, data, and observations and explains them in a coherent way. Hence, "only a theory" is rather meaningless. I. The Phylogenetic Tree of Life One prediction that is made by evolution is that if evolution via common descent were true, then we should be able to place life in a hierarchy – a tree if you would. We should be able to develop an objective classification scheme for all organisms. We call this the Phylogenetic tree of life. The above lists a basic Phylogenetic tree (Theobald, 29+ Evidences for Macroevolution - Part 1: The Unique Universal Phylogenetic Tree). Note that “hypothetical common ancestor” does not mean that we guess that it existed; rather it means that we infer that it existed. This Tree of Life and the line of evidence can easily be falsified if we find an organism that cannot fit into any known taxonomy or hierarchy on such a tree. The video to the right explains how Phylogenetic trees are constructed and why they offer such great proof for evolution. II. Evidence from our bodies “Nothing in biology makes sense except in the light of evolution.” -- Theodosius Dobzhansky. A. Remnants of the past Our bodies yield much evidence for evolution. I will explore several key points from our body that presents evidence for common descent: 1) Vestigial structures; 2) Atavisms; 3) HERVs; and 4) Pseudogenes. A-1. Vestigial structures Contrary to Creationists claims, a vestigial structure is not a structure that is functionless. Indeed, a vestigial structure is a reduced and rudimentary structure compared to the same complex structure in other organisms. Vestigial characters, if functional, perform relatively simple, minor, or inessential functions using structures that were clearly designed (or evolved) for another complex purpose (Theobald, 29+ Evidences for Macroevolution - Part 2: Past History). Example 1: Goosebumps Goosebumps are vestiges of a time when our ancestors had hair covering their entire body. The function of the goosebump is to raise hairs to make better insulating the animal when the air is cold, or to make the animal look larger and more menacing when frightened (Fairbanks). Example 2: The ostrich wing "The wing of the ostrich resembles those of the gyrfalcon and the hawk. Who does not know how the speed of the gyrfalcon and hawk in flight exceeds that of other birds? The ostrich certainly has wings like theirs but not their speed of flight. Truly, it has not the capacity to be lifted from the ground and gives only the impression of spreading its wings as if to fly; however, it never supports itself above the earth in flight. It is exactly the same with all those hypocrites who pretend to live a life of piety, giving the impression of holiness without the reality of holy behaviour." The Aberdeen Bestiary http://www.abdn.ac.uk...;Folio 41v , c. AD 1200 — on the ostrich, its vestiges a symbol of hypocrisy since the 2nd century A.D. The ostrich wing is a vestigial structure as the wing is useless for flight. No organism can have a vestigial structure that was not previously functional in one of its ancestors. Thus, for each species, the standard Phylogenetic tree (listed above) prohibits what types of structures we cannot see. For example, we will never see a man with vestigial wings used to fly. A-2. Atavisms Atavisms are a slam dunk for common descent. Atavisms offer powerful evidence of how anatomy evolves. Unlike a vestigial structure, an atavism is a lost ancestral structure that occasionally reappears in a few individuals (Fairbanks). I will list below two common forms of atavisms. Example 1: Humans with tails The most striking (at least to me) atavism is the formation of humans with a true tail. Occasionally, human infants are born with a small tail that persists into adulthood if it is not surgically removed. More than 100 cases of human tails have been reported. Less than 1/3 of these are “pseudo-tails” [1] (Dao and Netsky) This picture above shows an x-ray of a human tail (Theobald, 29+ Evidences for Macroevolution - Part 2: Past History). III. Evidence from the genome A pseudoegene is a gene that is disabled. It is one that has lost its entire function via a disabling mutation. There are numerous such pseudogenes in humans and I am going to explore a couple of them in this debate. A. PseudogenesA-1. CMAH 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. [2] 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. (Fairbanks) Conclusion The evidence that I have given you in this debate is not even the tip of the iceberg. Many books have been written on the evidence for evolution and I can easily write hundreds of pages on evolution. Yes we evolved, yes we are evolving; along with the rest of life—how we use our knowledge of evolution directly impacts the future of life on earth. [1] “Pseudo-tails” are not true tails; they are simply lesions of various types coincidentally found in the caudal region of newborns. [2] Neanderthals apparently had this same CMAH pseudogene meaning that the disabling mutation occurred before the splitting of the two lineages. Bibliography Dao, A. H. and M. G Netsky. "Human tails and pseudotails." Human Pathology (1984): 449-453. Pub Med. <http://www.ncbi.nlm.nih.gov......;. Fairbanks, Daniel J. Evolving: The Human Effect and Why it Matters. Amherst: Prometheus Books, 2012. Print. Theobald, Douglas. 29+ Evidences for Macroevolution - Part 1: The Unique Universal Phylogenetic Tree. 16 April 2012. 16 August 2012. <http://www.talkorigins.org......;. —. 29+ Evidences for Macroevolution - Part 1: The Unique Universal Phylogenetic Tree. 16 April 2012. Document. 16 August 2012. <http://www.talkorigins.org......;. —. 29+ Evidences for Macroevolution - Part 2: Past History. 16 April 2012. 17 August 2012. <" target="blank">http://www.talkorigins.org......;.