Saturday, March 13, 2010
Facilitated Evolution
As humans expand over the Earth's surface, our methods of making life easier for ourselves grow in number and complexity. Not least in these is breeding: selective breeding and domestication are both examples of humans determining the path of evolution, picking and choosing certain traits that are desirable to us, like in the Dog movie we watched in class, from wolf to man's best friend. Mr. Coyne also mentions this in his book, in Chapter 5, the Engine of Evolution, the section Animal and Plant Breeding (p. 125). But to what degree do we as humans have control over evolution? Are there factors we can't control in an organism's evolution? How does our tampering with natural selection help us, and how does our selection of traits help the organism? And now, with the genetic information we have, should we mess around with evolution?
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I definitely agree that humans are playing an increasing role in the facilitation of evolution. The dog example mentioned in the prompt, movie and Coyne’s book is proof that human selective breeding contributes to evolution. As we humans chose to take care of docile, hunting, loyal or “pretty” dogs. In result, these types of dogs were better able to survive and reproduce because the care they were given by the humans. Thus, the dogs evolved such that hundreds of breeds of dogs exist today.
ReplyDeleteThis concept of selective breeding is not limited to just animals; the selective breeding of plants for food has had an equal control over evolution. In Human Geography last year, we learned that when agriculture was first beginning, the humans were already practicing selective breeding. Early humans who planted corn would replant the mutant corn seeds which yielded the largest stocks of corn in hopes of producing more large corn stalks. Large corn thus had a selective advantage because it (the larger corn) was more likely to be planted by humans. As a result, corn that we buy today is significantly larger than the corn harvested by our ancestors who lived thousands of years ago. This type of selective breeding, in addition to exemplifying the theme of evolution, also shows the relationship between structure and function. The larger structure of some corn stalks, suits the function of being more attractive for humans to replant.
Facilitating evolution of plants has undoubtedly already existed for thousands of years. Recently, humans have begun facilitating diffusion in a far more controversial way: genetic engineering. Scientists are able to insert plasmids contain certain beneficial genes into varieties of crops. For example, scientists can engineer rice to contain more vitamins or proteins that the population consuming the rice needs to survive. By preventing malnutrition, genetic engineering is seen as a good thing. In contrast, many others call this type of genetic manipulation unnatural and refuse to eat genetically modified food. It comes down to personal opinion, how far is going too far in the manipulation of other forms of life?
I agree with Samantha that humans have domesticated crops and animals to suit their needs. If domestication doesn't suit us, then why take time and energy to domesticate anyhow? But to answer your question, Jolyn, how much it has helped us and the organism, I think it actually depends on the species.
ReplyDeleteHumans, obviously, always try to promote domestication and breeding to suit their needs, such as breeding hunting dogs to help catch food.
For example, hunting dogs are domesticated so they're agile and could help hunt food for their master. This is an example of a symbiotic relationship, in which case the dog and master help each other obtain food (and if you think the master doesn't do anything, remember that the master has to be the one who brings up the dog in the first place)
However, some traits humans want to see but don't help the dog also come during domestication. I remember a program I was watching a few weeks ago on the domestication of dogs. They discussed bulldogs, and how their skin has huge wrinkles. The wrinkles on bulldogs are the work of humans who breed bulldogs to have huge wrinkles. Coyne notes that "breeders have virtually sculpted these dogs to their liking," however, this does NOT help some species (128). With large wrinkles on a bulldog's skin, this causes the bulldog to be heat intolerant. A bulldog constantly pants in order to keep its body temperature level. This is our work; we, humans, have done this to make the common bulldog's life harder.
How about corn plants that were domesticated to be tall and bear more kernels? From one perspective, domesticating corn to be longer has helped the corn crop, and it would allow it to have more offspring if grown in the wild. However, this is not the case, since humans harvest the corn's babies.
Therefore, human regulation of nature can, in one perspective, ethical if it provides a symbiotic relationship like the common hunting dog. However, it is unethical if we intend to breed organisms and leave them with bad traits like the bulldog.
As for crops, human intervention helps us, but only helps the crop to the extent that better genes will be expressed with the tradeoff that the crop will ultimately die for the sake of our race.
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ReplyDeleteThough there is no doubt that human domestication has utilized natural selection to their advantage, the advantages given to the domesticated organism is questionable. As Henry had stated, if the domesticated organism is designed to be a crop or livestock species, the domesticated traits would often be a disadvantage to the organism, not only because the organism is gaining traits that it would be killed for, but because these traits generally would make the organism less fit for survival in the wild. The same can be argued for organisms such as dogs. Though domesticated dogs are given the benefits of human care, they lose traits that would be necessary for survival in the wild, thus putting the dogs at a disadvantage if the human factor were ever to be removed.
ReplyDeleteThe extent of human domestication, until recently, could not reach the potent of natural selection. Human domestication generally fails to cause speciation, as breeds are capable of breeding with other breeds. Therefore an important pillar of evolution is missing from human domestication. The new ability of humans to alter the genome of organisms overcomes this issue, however, and could easily open up paths that were previously closed. Altering the genome is not gradual however, and therefore also cannot truly be called evolution.
I believe that altering the genome of organisms is a perfectly legitimate exercise. Though this new technology could have negative implications on the ecosystem by creating new super-variations, the gradual fall of the natural world to human society seems inevitable and there is only question toward the rate at which it occurs. Eliminating a technology with such great potential in favor of delaying an inevitable outcome appears illogical, and the theme of Science, Technology, and Society indicate that the new technology of genetic modification should be used to help solve problems such as world hunger. Instead, measures should be taken to control these organisms if they do spread beyond their intended habitat. For example, a "kill" gene could be added to the organism that would make it extremely vulnerable to certain toxins. We can achieve this by isolating genes that make plants vulnerable to certain toxins using DNA microarrays to test a genome for toxin vulnerability. (Campbell 410).
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ReplyDeleteI agree with Henry and Ray in that artificial selection, or selective breeding, though parallel with natural selection, often works in opposition to the natural process. While the goal of natural selection is to achieve the best adaptations for survival, the goal of artifical selection is to achieve the best adaptations for human use; in artificial selection, according to Coyne, "the criterion of reproductive success is human desire rather than adaptation to a natural environment" (Coyne 127). For instance, while dog breeding in order to create "Sam the Ugliest Dog" won the owner her 15 minutes of fame on primetime TV after the dog earned 3 awards, selective breeding in no way helped Sam's reproductive success - in fact, it may very well have harmed the dog, for he was euthanized due to heart failures (http://www.samugliestdog.com/theugliestdog.html).
ReplyDeleteThe question of whether tampering with natural selection should continue (and to what extent) has become more critical in dealing with genetic engineering. Agriculturally speaking, the genetic modification of crops is pertinent and being widely discussed today because of its alleged implications for humans. With the genetic knowledge we hold, some claim that genetically modified crops could substantially contribute to solving world hunger. Since this would happen partially due to an increased amount of crops, it seems as though the process would work alongside natural selection, improving the organisms' reproductive success; however, genetic modification eliminates genetic variation (and evolution works to create variation). If one organism in a field of genetically modified corn is susceptible to a certain virus, that virus can wipe out the entire group (http://www.safe-food.org/-issue/dangers.html).
Genetic engineering and interference with natural selection becomes even more ethically controversial with genetic counseling and modification for humans. Should we go ahead and increase chances of survival by avoiding the inheritance of disease genes? Most, including myself, believe that treatment of illnesses by genetic design in humans is completely okay. Once genetic design interferes with natural selection so much that parents are meeting with genetic counselors to "order" a baby with blonde hair and blue eyes, though, we are again decreasing variation and thus conflicting with the evolutionary process (which, in my opinion, should not be done).
This debate falls under the theme "Science, Technology, and Society," which so often consists of huge and potentially helpful advances vs. complex ethical issues. Issues dealing with this theme constantly bring up Sam's question - how far is too far?