In pages 81 - 85, Coyne shows us that bad design is a mark of evolution. One example of bad design is the "small gap between the human ovary and Fallopian tube, so that an egg must cross this gap before it can travel through the tube and implant in the uterus". The design is "maladaptive" because it evolved from fish without consideration of the Fallopian tube until much later.
Why does bad design support evolution? What arguments could a Creationist make about bad design to support himself?
Name an organism with a feature that could have been better placed/designed. Explain the bad placement by tracing the evolution of the feature.
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Many people argue that evolution must be possible because "if organisms were built from scratch by a designer-one who used the biological building blocks of nerves, muscles, bone, and so on-they would not have such imperfections. Perfect design would truly be the sign of a skilled and intelligent designer" (pg. 81). An example of bad design is in the flounder, which is a flat fish. Flatfish are born as normal looking fish that swim vertically and have one eye on each side of their body. After a month, however, one eye begins to move upward and joins the other eye so that there is a pair of eyes on either side of the body. The skull changes shape to promote this movement. This is an example of poor design because the fish should be flat from birth and be able to lie on its belly, not have to achieve flatness by lying on its side, moving its eyes, and deforming its skull. This all stems from its evolutionary heritage, however. Flounders evolved from normal symmetrical fish. They found it advantageous to flip on their sides and lie on the sea floor to hid from predators and their prey. This was an issue because their bottom eye would be useless and could potentially be damaged. Natural selection selected for the movement of the eye and deforming of the body so that the fish had a better chance of survival and reproduction. There are many other examples of poor design. In human females, the birth canal passes through the pelvis. If a baby's skull is significantly larger than the pelvic opening, then the baby cannot be born naturally and the mother must have a caesarean selection. There are unnecessary wings in birds such as the ostrich that don't fly. This is bad design because it could cause them harm because they can get in the way and are easily injured. The existence of the pharynx, a passage used for both ingestion and respiration, is bad design because it increases the risk of choking. According to (http://en.wikipedia.org/wiki/Argument_from_poor_design) some Christians may believe that "because of mankind's sin, the world is fallen, and full of imperfections. It is argued that imperfections and apparent sub-optimal design persist in the world because of sin." Another website, (http://www.godandscience.org/evolution/designgonebad.html#3Ix5T1Tb9FOo) argues that many evolutionist's examples of "bad design" are "bad examples." They explain that the appendix contains a significant amount of lymphoid tissue. Similar aggregates of lymphoid tissue occur in other areas of the gastrointestinal system. These lymphoid tissues are involved in the body’s ability to recognize foreign antigens in ingested material. Some may say that many examples of bad design are wrong because these traits are still used in species today, however, they greatly support the theory of evolution and how natural selection has allowed populations to adapt better to their surroundings.
ReplyDeleteThe argument that supports the idea that bad intelligent design is evidence of natural selection is called the dysteleogical argument - it is an argument agains the existence of a creator God. Scientists believe that a creator God would create organisms with optimal design, and many organisms have features that are suboptimal, so therefore, God did not create such organisms. Some Creationists counter this argument by stating that if an organism shows good design, then God designed it, but if an organism shows bad design, it's a result of Adam and Eve's fall from Paradise (Genesis). For example, in humans, the existence of the blind spot in the eye is bad design, according to an article by Robert Harrand. He states that "The human-eye is an excellent tool for viewing the world, but it is far from perfect. The optic nerve, the bundle of nerve fibres that transit electrical signals to the brain, is attached to the eye via the retina. This creates a blind spot - a whole patch in human vision where nothing can be seen." The evolution of the blind spot in the human eye is hard to trace. According to an article on LiveJournal.com, our eyes have ciliary photoreceptors that are incapable of discerning the polarization of light. All animals, including both vertebrates and cephalopods, got their eyes from a common prebilaterian ancestor. The dilemma of the blind spot arises only when the oxygen is delivered using blood. That is where the crucial difference between the cephalopods and vertebrates emerges. The cephalopds belong to the clade of animals having blue blood: instead of using hemoglobin in which O2 is carried by Fe, they use hemocyanin where O2 binds to Cu. The cephalopods pass huge amount of water through their gills, extract lots of oxygen and immediately deliver it to their organs in a single pass. It happens that our retina is one of the highest O2-consuming tissues of the body. O2 is delivered to the retinal receptors directly by hemoglobins in the blood vessels. These vessels are absolutely essential there, next to the cones, because oxygen has no means of diffusing through its thickness. They deliver oxygen to their retinas using extracellular hemocyanins, so they do not need the blood vessels to go right next to their rhabdomeres. Faster O2 metabolism and lack of cooperativity make this mode of oxygenation possible. The animals that deliver oxygen using hemoglobin containing specialized blood cells cannot allow themselves such a luxury. Since the arterial blood has to enter the retina anyway, nature chose to use this entrance for the optic nerve, which makes good sense: the nerve grows around the artery, so the nerves get their oxygen, too. Better still, our sharp central vision is by the fovea, which is cleared of blood vessels and innervated and oxygenated from behind, through the choroid. That is the reason why the fovea operates under hypoxic stress under bright light and why we avert our eyes from it. Marine animals do not encounter this problem because they do not deal with bright light, so the oxygen demand of their retinas is lower.
ReplyDeletehttp://en.wikipedia.org/wiki/Argument_from_poor_design
http://geneticsevolution.suite101.com/article.cfm/how_to_design_a_better_human
http://shkrobius.livejournal.com/143323.html
Another example of this bad design theory is the human knee. It's job is to bear and absorb the weight of our bodies as we stand, walk and run. However, it has a very poor design to perform this task, as bending in the opposite direction would provide a much more effiecient method of bearing the weight. Especially when walking or running, bending the knee in the opposite direction would cause it to ask much like a spring, bearing the weight of the body as it comes down on it, and then releasing that stored "spring" energy as the weight comes off of it. The design of the knee causes it to be almost completely dependent on the ligaments that surround it, the only joint that has such a great degree of dependence on its ligaments. This continued strain often causes ligament damage, and the risk is especially high for athletes because of the high amounts of stress put on the knee. Knee injuries are the 5th most common sports injury, and the most common sports injury to joints. More and more companies which provide prosthetic legs to athletes are switching to a design of prosthetic that bends in the opposite direction of how a normal knee bends. These new artificial legs have proven to show a much higher level of performance than the old artificial limbs, and many Paralympic records were broken at the Beijing Games in 2008 with these more modern artificial limbs. When compared to animals with a significantly different knee and leg design, such as kangaroos, our performance pales in comparison. The kangaroo's leg design allows it to act like a spring, compressing and then releasing energy to spring it forward.
ReplyDeleteSources:
http://www.stvincent.org/ourservices/totaljoint/kneerep/knee/default.htm
http://www.sciencedaily.com/releases/2008/10/081003123250.htm
http://men.webmd.com/guide/seven-most-common-sports-injuries
http://answers.yahoo.com/question/index?qid=20090410010737AAnIiPq
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