This week's readings cover Jones' chapters on the laws of variation and difficulties that arise from Darwinism. One common theme interwoven between the two chapters is the misunderstanding of the innately complex process of inheritance. Below are some of the important concepts from the readings and a couple of (hopefully useful) discussion questions to start things off.
Importance of Genetics
Genetics, as Jones discusses, seems to bring as much confusion to our understanding of inheritance as it does answers, both of these contributions are asserted as being further proof of evolution rather than discrediting it. Jones begins with Mendellian genetics which provide our most basic understanding of inheritance and goes on to discuss mutations, the need for variation, and 'junk' DNA (though he does not use this term). As discussed in class, without variation there can be no evolution because all organisms would be identical, thus having nothing for evolutionary forces to act upon. Variation is rooted in the most primal and favorite pastime: sex. Sexual reproduction, as opposed to asexual reproduction, is the main mechanism behind variation. This particulate, not blending, process of reproduction provides an equal, random combination of parents' genetic make-up.
Mutations within genetic code can occur in several ways and are a primary force of evolutionary change. Jones points out that these mutations originate within male mammals more often than their female counterparts due to male gametes dividing throughout his lifetime, thus increasing the chance of error for subsequent generations of sperm. When mutations are beneficial to the reproductive success and survival of the offspring, natural selection will favor them.
Outside of Genetics
There is more to natural selection than genetics and he utilizes numerous examples of Lamarckian evolution, or inheritance of acquired characteristics, but never mentions this theory by name. The influence of this process on evolution cannot be dismissed just because it does not make sense biologically and Jones stresses this by emphasizing the importance of parents passing on education/social rank/nutrition to their offspring. There is not biological link between a mothers rank in the pecking order of the society she is about to bring offspring into, but whether or not she is able to provide sufficient nutrients while her young is in the womb, and later as a postpartum dependent, is directly related to that rank.
Difficulties on Theory
There are several holes, or apparent holes, within our understanding of evolution for ID proponents to build off of, but even these arguments tend to misapply and misinterpret evolutionary processes. The lack of intermediary forms is a popular, yet flawed, argument. In truth, everything is an intermediate form because evolution runs on an endless road, not a treadmill. I believe Jones provides a good example of intermediate forms when discussing forms of hawthorn fly. Variations, or subspecies, of this organism exploit different ecological niches and do not breed across those lines outside of the laboratory. It seems very likely that after more time passes by that these subspecies could adapt so well to there particular niches that they will no longer be capable of interbreeding even in a lab and, in biological terms, will speciate.
In Conclusion
The most valuable concept of this section might be that evolution works more as a "tinkerer" rather than as a "trained engineer". We cannot know where evolution will take organisms next because we cannot know what environmental changes are lying in wait for us to adapt to. Natural selection can only act on what is present and does not give consideration to whether a trait that is beneficial now will be deleterious later.
Some questions to promote discussion:
1) Aside from the few mentioned above, what are other apparent 'problems' or 'holes' are there in evolutionary theory that are explainable by someone with a good understanding of the subject?
2) What examples could you provide to explain natural selection to a creationist that hinges on the fact that there is no omniscient designer behind it all? In other words, what is a change that has evolved that could become or has already become possibly disadvantageous? In humans, a male's penis and testicles on the outside of the body would seem an obvious one.
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Chapter VI is a crucial assessment for students of evolutionary theory. Addressing the difficulties and noticeable holes can illustrate the complexities of the theory and can also help us build a response for those still critical at the same time.
ReplyDeleteIn response to Anthony’s initial question, another proposed problem within the theory relates to why certain traits emerge that don’t seem to have any apparent importance to the body. Perfection being a relative term (explained on pg 128) is not the end goal of evolution, as we are on a continuous journey of changing traits. Many characteristics which appear irrelevant, like a cow’s spots or a giraffe’s tail, are actually very useful. Some variations may just in fact be “left over” or still in a state of change, but the point Jones makes is that many animals just haven’t been studied in depth enough yet to make any clear evaluations.
The eye is a common example by anti-evolutionists to explain that some traits are just so advanced that natural selection could not have occurred. We must understand the long gradation process under varying conditions that absolutely could result in our different organs. Jones maintains that “our eye is imperfect, but we are used to what it cannot do” (pg 129). That we cannot see ultraviolet color, like bees can, is clear proof of this.
Touching on question 2. How can you prove to an creationist that natural selection exist? This is a losing battle; for a creationists can simply imply that it was God’s will or other simple conditions caused the problem, which doesn‘t involve natural selection or evolution. The example here is humans moving for quadrupedal to an upright posture. Some would explain the process of bipedal as an imperfect balance (disadvantage); causing back pains and aches common in humans. However, the creationist can say that it was God’s will for back problems, or use recent modern research to state that back problems are simply caused by the abuse of the body in modern life through lack of exercise, poor posture, and stress; not because of evolution. One can take any advantage and turn it into a disadvantage and any disadvantage into an advantage.
ReplyDeleteHere is a quote I found interesting:
"Intelligent design may be interesting as theology, but as science it is a fraud. It is a self-enclosed, tautological 'theory' whose only holding is that when there are gaps in some area of scientific knowledge — in this case, evolution — they are to be filled by God."
Washington Post columnist Charles Krauthammer
If the natural world were really full of "perfection", we would not really be able to distinguish between a supernatural and a natural origin for these adaptations. After all, the predictions of both ID and Darwinism include the fact of adaptation. That is, animals and plants are supposed to be adapted to their environments according to both theories. But when we find obvious examples of less than perfect design in the world of nature, e.g., anatomical devices that work just good enough to outcompete other taxa but far from perfect designs, then Darwinian evolution becomes the superior argument.
ReplyDeleteOne example from the world of biological anthropology involves the bipedal adaptation that all hominids share. Are we perfectly adapted bipeds? Are our anatomical adaptations in the hindblimb, pelvis, and vertebral column the obvious work of a perfect and all-knowing divine designer? Or is bipedalism cobbled together from the raw material present in our tree-climbing, anthropoid ancestors? What do you think?