"1. If evolution is unguided and is a completely natural process, how does nature "KNOW" which traits are beneficial and which traits are not? For example, how did nature know to make a digestive system and a sewage system for the removal of our bodily wastes? Did these systems just "pop up" out of nowhere in organisms? Or did organisms start out with half-systems and couldn't remove waste and digest food? If the latter is the case, how did organisms ever survive
long enough to reproduce?"
This seems to be a common question among creationists. Given the idea that organisms can evolve new traits over time, they ponder how Nature can "know" when and what kind of adaptations to evolve. The answer, of course, is that Nature doesn't "know" either of these things. Nature is, to borrow a metaphor, a blind watchmaker. There is no "when" simply because the processes that drive evolution - natural selection - are at work all the time. Organisms are constantly evolving, whether it be on the micro or on the macro scale. As long as there is a selective pressure, organisms will continue to evolve. That is part of the key to the "what" question as well. Nature doesn't "know" which traits should be evolved. The traits that occur are a consequence of the environment. To answer the example in the question above, organisms that had a method of removing bodily wastes - even a very primitive one unlike our own - were more fit (that is, more likely to live to reproduce) than those without. Eventually, the number of organisms posessing digestive systems would outnumber those without. Of course, such systems would not just "pop into existance". Rather, they would be the result of a gradual building up of more primitive traits. Over time, the system would become more and more complex, since a "better" system would provide a fitness advantage over those with the previous version. At no point in this process did Nature say "Hmmm I think that organism needs a better digestive system, so I'll make them evolve one." It was the environment, selecting for organisms which gain reproductive advantages, that allowed complex systems to come into existance.
I think part of the reason why so many creationists ask this question is that they cannot get their minds around the possibility that there isnt an intelligent force behind the existance of life. They are so ingrained with the idea that an intelligent being - God - runs the universe that, when presented with the idea of evolution, they figure that there still must be an intelligence behind it, that Nature is a conscious, thinking entity (and seeing, rightly, that Nature doesnt posess such a property, they claim that God must be the Creator). For them, an intelligent designer is not a simple assumption but rather an axiom.
Saying that evolution "works to give us traits to survive better" is a bit of an understatement. Evolution works in such a way that traits that allow us to be more fit - to have a greater chance of reproducing - are selected for. Survival post-reproduction doesn't really matter from the point of view of evolution. As long as an organism reproduces, its genes gets passed on, and the better the organism can ensure that it lives long enough to do this the better. So it's not really survival that natural selection favours: rather, it's reproductive success. Evolving an immuminity to fire would not really fit this description. Surely, an organism which evolved immunity to fire would survive over one which is not immune in an environment that is constantly bombarded with fire, but such environments do not exist. Perhaps if you moved a population of squirrels to the bowels of Hell itself for a couple million years you'd get fire resistant rodents, but such a situtation is highly improbable in reality. In the real world, organisms are rarely exposed to fire on a regular basis. An immunity to fire would not probive a distinct reproductive advantage. Quite to the contrary, if any organism did somehow evolve and immunity to fire, it would be likely to be at a reproductive disadvantage, since it would be expending energy and resources to support an immunity that the others in the population would not have to.
"2. It is often said by evolutionists that we have certain traits because they make us survive better. For example, we have eyebrows because it keeps things out of our eyes. (This is said as if nature actually KNOWS it's keeping stuff out of our eyes and decided to stick with eyebrows.) But, if we really do have certain traits because it makes us survive better, why didn't we evolve immunity to fire? Surely if we had the ability to not be harmed by fire, it would be a HUGE survival advantage to our species. But, we do not see this despite the fact that evolutionists say that evolution works to give us traits to survive better. We are immune to other certain types of things. Immunity to fire would've been a huge survival advantage, don't you think?"
This is, of course, ignoring the fact that being immune to fire is a physical impossibility. The reason fire is harmful is because it's high temperatures cause physical damage to matter; it results in irreversal changes to matter it comes into contact with. Our flesh burns, our enzymes denature, our proteins break apart. The reasons these things happen is purely a chemical one. Developing an immunity to fire would mean developing chemistry totally alien to our universe. And while evolution can produce some amazing things, THAT would be a feat even Mother Nature can't do.
"3. if nature doesn't "know" anything and is unguided, how does our body know when something bad is being put into it to cause us to cough? If nature was unguided, there should be no reason why our body "knows" we have to cough. How does nature know what is good and bad? "
This is because we have a complex and effecient immune system. Foreign particles have traces on them that tell our bodies which are "bad" and which are "good. These are called antigens. We have special cells that recognize antigens and can determine which particles are harmful and which are not. This is what helps us fight off bacteria and viruses: they all express antigens which our immune cells can recognize; when such a pathogen is detected by these cells, they are eliminated (through a variety of complex ways, the scope of which is beyond the material of this article).
Similarily, when cells in the lining of the throat recognize that there are foreign particles present that should not be there, they excite a coughing reaction which works to move those particles up and out of our bodies. This is how our body "knows" when to cough. How could such a process have evolved "if nature was unguided"? It couldn't. But nature ISN'T unguided. Nature's hand is guided by natural selection. An organism with a rudimentary immune system would obviously have a reproductive advantage over one without such a system; likewise one that could remove foreign particles from its throat by coughing would be less prone to infection and the like than one who could not. Coughing provides a bonus to fitness and is easily selected for.
"4. If surviving more efficiently is one of the main purposes of evolution, why do so many people get heart disease? Shouldn't we have evolved to a point by now where fatty foods don't harm us because it would make us survive longer and better? Right now, fatty foods can kill you and give you a heart attack if you eat it too much. Some survival advantage that is for us, huh? If we all had the ability to eat any type of food we wanted without getting heart disease, that would be an even GREATER survival advantage, don't you think? "
This is kind of a rehash of the fire-immunity question above. I wont go into detail explaining why we havent become able to eat whatever we want without consequence, so I'll summarise in a few lines:
The particular effects fatty acids have on our bodies are limited by our biochemistry. That is, the reason we have adverse effects from eating too much fatty acids are biochemical ones and, thus, are governed by the laws of biochemistry. Evolving an "immunity" to these effects would mean evolving chemistry that is counter to the chemical laws which govern our (known) universe. Given enough time, we may evolve in such a way that the effects of greater fatty acid intake are less and less adverse but developing an "immunity" is highly improbable, if not impossible.
"Yet, in spite of all these objections, evolutionists will INSIST that evolution gives us traits to be able to survive better. I guess evolution doesn't see a need for us to REALLY be able to survive better considering we can burn in fire and die from too much eating. "So basically this guy's views on evolution can be summed up as "Why haven't we evolved to be invincible? The fact that things can hurt us shows that evolution is false. Besides, organisms can't "know" when to evolve, anyway." As usual, these questions can be answered with a simple undertandsing of evolutionary principles and not taking the idea of an intelligence ruling the universe as a given. Such questions highlight the need for a better teaching of evolution in highschools, and a set curriculum for homeschooled kids (since the only exposure to evolution most of them get are lies from their parents, who are not qualified to teach anything, that evolution is an evil conspiracy lead by scientists). With the trend of school boards in the States trying to pass misnomered "Academic Freedom Bills", it's likely that education on the subject is going to worsen. These questions, as absurd as they are, might become the norm for even the most "enlightened" (and I use the term very lightly) of creationists.