Sunday, April 5, 2009
Intelligent Life
In his book, Carroll repeatedly connects environmental factors to the biological adaptations they promote. After enough time, he claims, the chance of an adaptation with a selective advantage evolving increases. It is through the build-up of these chance mutations that the diverse life on Earth that we have today arose. And then came Homo sapiens. Is it possible that the evolution of the single most dominating organism to walk the planet brought with it the downfall of evolution itself. In theory, if just being a human is a selective advantage, and physiological traits really don't factor into offspring survival rates, then won't humans have reached an end in their evolutionary road. Discuss if this is truly possible and if not, why is this not possible? Also, what were the events in our planet's history that set up the development of Homo sapiens? Under what conditions did we develop the selective traits that we have today? Finally, is it possible for another intelligent organism to develop such as ourselves independently from another origin, such as the case of the multiple developments of potassium channel blocking neurotoxins around the world?
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ReplyDeleteAddressing Theodore’s point that “for every invention that man has created, nature has created an even bigger force. An example would be bacteria that have developed strong protection against antibiotics over the years.” This doesn’t exactly demonstrate that humans are still in being subjected to nature’s ominous selective force, it instead demonstrates human’s divine hand in natural selection. It demonstrates human’s effect on its surroundings. If anything, humans are just speeding up the evolution process of bacteria around us. Every time we develop a new antibiotic then eventually some “super bug” or multiresistant bug will have the resistance for it, and with the selective advantage to survive and reproduce in the hostile conditions they will soon become the only bug and be immune to all possible antibiotics. This is only possible because of its rapid reproduction rate which allows it to create thousands of offspring within hours and add genetic diversity to the gene pool. This super bug will then go on to evolve while human defense will stay static and our evolutionary journey will slow down.
ReplyDeleteA prime example of a human’s lagging evolutionary ride is the allergy crisis that begins to plague the world. Humans have become clean freaks, or germaphobics not allowing themselves or their loved ones to become exposed to any type of bacteria or dirt. Kids are no longer allowed to play in the dirt outside; instead they are placed in humidified sanitized white walled rooms where they will play their video games with sterilized controllers. This lack of exposure seems to be harmful rather than helpful, opposing what their parents think. “More than half of all Americans test positive in response to one or more allergens, double the percentage who did 30 years ago, a new study reports,” US news reports. This seems to prove that Humans are on the back track of evolutionary trends rather than progressing. It shows that our bodies which used to be able to protect itself from this antigen are no longer to defend for themselves. That’s why we have to have artificial vaccinations.
Vaccinations work because of the interactions between antibodies and antigens. Antibodies released from activated B cells interact specifically to a certain molecular shape of the antigen. B cells are activated to act accordingly because of their antigen receptors. Antigen receptors are not however born to be ready to fight antigens. They need to learn or rather create a memory of how to attack the antigen. When an antigen encounters a lymphocyte, it stimulates the lymphocyte to from two clones. One clone, called the effector cells, are short lived cells that will combat the same antigen. The other clone consists of memory cells, which will be long lasting and be ready in case of another attack by an antigen. This entire process of selective proliferation and differentiation of lymphocytes that occurs when the body is first exposed is the primary immune response. During this time, the T and B cells will create antibodies that will destroy the antigen and develop immunity. So a vaccination is like a small dose which gives the body a big enough chance to survive and kill the antigen at the same time develop a stronger immunity in case of stronger doses.
What makes humans special is that entire process. We acquire our immunities while bacteria inherit their immunities. This trait gives a huge selective advantage in surviving where in a world the human body has become static in the evolutionary trend. I wouldn’t however say static though, just very slow.
As for the other questions from Jack, Numerous answers exist for while humans have become the most dominating species on earth. The atmospheric change into oxygen, dry lands arising, development of the highly specialized brain, and the list goes on.
http://www.usatoday.com/news/health/2005-08-07-allergy-sensitivity_x.htm
http://en.wikipedia.org/wiki/Antigen
http://en.wikipedia.org/wiki/Vaccination
I am only going to answer part of this question. I do not believe that it is possible for natural selection to stop working on humans, at least not unintentionally. Assuming that humans don’t intentionally try to develop technology to bar natural selection (which is probably not going to happen), chances are that natural selection will keep working on humans. Why? Because physiological traits do have an effect on offspring survival rates. It may not be as obvious as in animals, because humans are intelligent enough to overcome disabilities, and have developed medicines that cure all kinds of crippling diseases. Everything that nature has thrown to sweep man off his feet, man has created an effective antidote. Animals often cannot do this. However, this will not stop natural selection. There are two forces in the fight. For every invention that man has created, nature has created an even bigger force. An example would be bacteria that have developed strong protection against antibiotics over the years.
ReplyDeleteIn order to demonstrate that physiological traits do have an effect on survival rates, and that natural selection will still come into play, it would be best to use a simple example. Let’s say a man is born with a crippling disorder- Down Syndrome, for example. The average lifespan is about 49 years. The man will have reduced fertility, mental retardation, and many more hazardous symptoms. Chances are he will not reproduce and will die early. Now, being a human, the man can find all sorts of options to ensure a longer and happier life. Unlike an animal, the man can consult experts who can give him advice and treat his disorder to the point where he can live an almost normal life. He might even find a partner and have children. This is all possible because he is a human being, not an animal; he possesses more intelligence than animals so he can “cheat” his disorder in a way. However, the general trend will show that people with Down Syndrome will generally not have children, meaning that the mutation will not be passed on. If a mutation ceases to be passed on, it will eventually die out, unless something happens.
This is why natural selection will always be a force in nature: because it works on a grand scale. An individual might be able to fight off a disorder, but the general trend will decide what happens to the mutation. Humans have not reached the end of the evolutionary road. A beneficial mutation will work its way around the population and a detrimental one will disappear, because despite the efforts of individuals, the world is simply too big for humans to control.
http://www.newscientist.com/article/dn2073-downs-syndrome-lifespan-doubles.html
http://en.wikipedia.org/wiki/Down_syndrome
This was always an interesting and debatable question. I believe that humans do continue to evolve. According to an article, we are not the same humans we used to be 1,000 years ago. It is possible that people believe homo sapiens have stopped evolving because we look at evolution through the eyes of a person who lives up to 100 years. Evolution takes MUCH longer than that. It is impossible to gauge our evolutionary rate just by looking at one or two generations. If we look at us compared to the older humans, we can see that they did have a use for their appendix. The appendix actually had to do with bacteria; it was its “safe house”, according to another article.
ReplyDeleteAccording to the first article, "Human races are evolving away from each other," Harpending says. "Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity." He says that is happening because humans dispersed from Africa to other regions 40,000 years ago, "and there has not been much flow of genes between the regions since then."“ This means that we truly are diverging from each other as a species. Is it possible that we might actually evolve into different species based on our ecosystem? I believe that at some point, hundreds of thousands of years in the future, it’s possible if, for the most part, people do not move around much (such as moving across the world).
Humans are definitely evolving on an academic level. Would that not be considered evolution? We are learning more and more about everything every day and we are mastering the art of science and the natural world. It is true that humans have the ability to, essentially, control their resources and etc because we have the intelligence to mass produce our needs. Therefore, we really don’t have any limiting factors. For humans, a limiting factor might be money, not something natural such as predation.
It is completely wrong to say that humans are not evolving. Actually, according to many scientists, we are evolving much quicker than would be expected. If one is to look at a castle, it is noticed that the doorways are much too short for the average human being to walk through comfortably. This suggests that humans, have in fact, been evolving. We have been getting taller and taller over the years. According to an interesting blog with biologists, “We are now starting to see resistance to the AIDS virus in some African countries - something that would not have existed even 50 years ago. The rapid spread of HIV and its effect (generally death) has sparked some rapid evolution of resistance in the worst affected areas with those people who were lucky enough to have a natural immunity (by chance from their genes) are obviously surviving and having children when many millions of others are dying.” This means that we are evolving the ability to resist deadly diseases, a key part of sustaining a species. The biologist mentioned “rapid evolution” which therefore completely goes against your question, which was stating the humans have stopped evolving. On the contrary, human evolution has been sped up! We are changing our technology and our environment so fast that humans are evolving much quicker than the average wild animal would on an evolutionary scale.
I believe it is completely possible for another species to evolve into something as intelligent as humans. This generally tends to sound crazy, but out of the over 400 billion planets in space, there is a HIGH probability that intelligent life has evolved separate from homo sapiens. This poses the question of aliens, which I will not get into because it is not completely biologically relevant… ☺ But, I do believe that it is entirely possible for intelligent life to evolve separate from homo sapiens because, although we don’t know for sure, it most likely has on one of the other 400 billion planets in space.
This whole discussion ties into the biological theme of evolution. This is all about evolution and whether or not it has been occurring in humans. As has been argued, evolution is occurring at an extremely rapid pace in the human race. As compared to other species that have taken millions of years to evolve, it has only taken humans a few hundred years to evolve slightly, though noticeably. It is interesting to read different conversations people are having on the web. On person mentioned an interesting point; “Does physical strength and agility evolve along with intelligence? It is difficult to speculate, because all depends on the environment that pushes the evolution. But take the human society as example: physical strength is becoming less and less a survival advantage in a society, which is regulated by laws and where money is the most important evolutionary advantage. Also one can speculate that in the future, with the development of technology, some physical abilities can be substituted or aided by artificial means. So I would hardly expect an alien species that has evolved in intelligence and technology far ahead of us, to be physically very strong.” Therefore, this person is concluding, or implying, that humans have evolved to the point where they need to use their brains much more than physical strength. Also, he might be saying that one day, we won’t even need much physical strength because we can just have some kind of technological procedure done to completely eradicate the need for a physically strong body! Who knows???
http://www.sciencedaily.com/releases/2007/12/071210212227.htm
http://www.boingboing.net/2007/10/06/function-of-the-appe.html
http://www.askabiologist.org.uk/punbb/viewtopic.php?id=462
http://www.physicsforums.com/archive/index.php/t-78045.html
There are countless factors that determine the effect natural selection has on any given species. For this reason an entire region of natural selection involves the complicated and unique mathematics that applies to this area. With humans, this “countless” number only increases because of human's development of civilization. Although I believe that because there are so many factors it can not be said that evolution is absolutely not or absolutely is taking place in humans, I do believe that civilization has decreased the power of natural selection, and I will discuss a couple of the factors that lead me to believe this.
ReplyDeleteFirst, one must realize the differences between biological success and success according to society's standards. To be successful in an evolutionary standpoint, an organism must survive to reproduce healthy offspring who will also be able to reproduce. If this is what success meant to the everyday human being, life wouldn't seem so hard. Our standards of success have risen, however, so the stress on individual to achieve evolutionary success, or reproduction, is trivial. Reproduction is a task that most people can carry out regardless of minor flaws that might have inhibited their survival thousands of years ago. Why is natural selection blind to these flaws? Civilization has offered human beings solutions to such problems. As Theodore mentioned, people can now consult doctors to help their problems, and even deadly diseases are now being treated so that individuals can survive to the age of reproduction. For example, Galactosemia is an autosomal recessive disease that impairs an individuals ability to metabolize the sugar galactose. Before civilization, this disease would most likely be fatal early in life because of its severe symptoms such as learning disabilities and ovarian failure. The genes for this disease would most likely be erased from the Earth because those who possess the genes would not be able to survive or reproduce. Now, however, civilization allows 1) the recognition of the disease and 2) easy treatment options for the disease. With an easy treatment of avoiding galactose in the diet, one can avoid the complications of galactosemia.
My second point to address is the idea that our ability to combat harmful complications is a selective advantage in itself, one with enough weight to offset any complication that might result from random mutation. There is a problem with this because, as Carroll explained, most mutations are bad mutations, and natural selection filters these out. Since we have opened up the filter and decided to just instead deal with the complications instead. With enough time, these bad mutations will accumulate and cause too many complications for mere technology or civilization to combat. An analogy to this would be a person developing many medical problems and instead of curing each one, he or she simply takes a different medication for each problem. Eventually, this person is going to develop problems.
Is my belief that there will be a climactic time during human existence when we can simply no longer handle the problems using our superior intelligence? No. This is why in the beginning of my answer I said that the only conclusion I can draw is that natural selection will be less powerful. Darwin was the first scientist who spoke of the power of gradual change. This is what will occur. We will not simply keep hiding more and more evolutionary complications. They will slowly be erased because although the selective coefficient of many minor problems such as wisdom teeth mentioned in a previous thread will be hidden, it is inevitable that the worst mutations and disadvantageous traits will be forced out of the human race by natural selection; that is if the human race is not first erased by these traits. It is the minor disadvantages that natural selection will fail to erase.