miércoles, 28 de abril de 2010
The Ostrinia nubilalis and Ostrinia scapulalis are two very closely related species of pest caterpillars that only differ in their host plant. While Ostrinia nubilalis, which is commonly called the corn borer, "spends spring and summer feeding on its corn stalk before spinning a cocoon for the cold winter," the Ostrinia scapulalis has the same life cycle except it feeds on a weed known as mugwort. Up until recently these two caterpillars were classified as the same species, because the particular host plant seemed unimportant to scientists. After closer observation, however, scientists realized that the cultivation of corn has created a distinct difference between these two species. While mugwort is never harvested or grazed, corn stalks are cut down leaving only about 6 inches of the stalk in the ground. The harvested stalks are then burned or fed to livestock once the corn has been removed, either of which leads to the certain death of any caterpillar cocoons attached to the harvested stalk. The corn borer, however, has adapted in order to survive the harvest by climbing down the stalk before it spins its cocoon.
This example of evolution was very successful and occured fairly quickly relative to the evolutionary time scale, because of the fast turnover of generations (one each year) and the lack of contamination of the sample. There was no worry of a caterpillar who did not move down the stalk before spinning its cocoon of passing on its genes, because it would die before it got the chance. I also found this example interesting, because nature has almost given us a control with the Ostrinia scapulalis, which have not developed the same "descending behavior, called geotaxis," because it has no evolutionary advantage since mugwort is not cut down. This clearly shows evolution at work.
Darwin certainly wouldn't have taken these caterpillars for granted.
Full Article: http://www.nytimes.com/2010/04/27/science/27obborer.html
Remember when Darwin visited the Falkland Islands, and he noted a "wolf-like fox" as the only large native quadruped? It was about the size of a coyote, peculiar to the island, and apparently very tame, to the point of going into gauchos' tents at night to steal meat. Darwin thought that the tameness indicated that they had been brought over as pets when humans travelled to the island, and before leaving, predicted (correctly) its imminent extinction because it was so easy to kill (and then facilitated the process, of course, by taking samples). Recently, researchers at UCLA have looked at mitochondrial DNA from these samples and other samples, and determined that it was indeed a separate species, its closest relatives being South American canids. But it wasn't brought over by people, because the 5 samples they looked at had a common ancestor (one that was already speciated into their current form) 70,000 years ago, and people didn't even arrive in the New World until 13,000 years ago. Furthermore, the South American canids that it shares an ancestor with (the "toaster-like" bush dog and the maned wolf) separated off about 6 million years ago-- which is before dogs even show up in South America (2.5 mya). So apparently the ancestors of all three species (and some other ones, incluing a Patagonian canid) evolved in North America and then migrated south. Somewhat annoyingly, though, no fossils that look like the Falklands fox-wolf lineage have been found in North America.
As to how it got to the Islands: since the Falkland Islands were never connected with South America, the researchers think it must have floated over from the mainland on an iceberg, surviving the journey and subsequent stay on seals, penguins, seabirds, etc.
Apparently Darwin's notebooks associate the wolves with some of his first thoughts on evolution, since he mentions them in conjunction with the Galapagos finches and his idea that species change over time.
From an evolutionary standpoint depression should be seen as a malfunction of the mind that would make it less inclined to function in society or leave offspring and would therefore be selected against. However, depression is very prevalent throughout human history. While most mental illnesses remain in less than 1% of the population, clinically diagnosed depression is like the common cold. How can something that makes you lose sleep, your appetite, and your libido still exist in so pervasively?
Like the fever helps the immune system, depression may have an unknown effect on either performance at a given task or protection against sudden crises, but up to this date, I know of no experiments on the purpose of depression. It is always assumed that depression is a bad thing that needs to be cured with drugs. In conclusion, would Darwin have written "The Origin of Species" if he was depressed?
New York Times
martes, 27 de abril de 2010
At times throughout this quarter I have been amazed at the different windows of science that can all be accessed through the lens created by Charles Darwin. I’ve marveled at his contributions to the scientific fields of geology, evolution, psychology and the list goes on and on. However, this cerebral journey seems to be satisfying my need to learn about the man who revolutionized the way people think about science.
For some Darwin enthusiasts this journey of contemplation isn’t enough. Last year in honor of Darwin’s 150th birthday and the 100th anniversary of the publishing of his masterpiece On the Origin of Species a replica of the HMS Beagle set out to retrace Darwin’s footsteps. These Darwinians traveled 24,000 nautical miles in hopes of connecting with the great scientist. Their epic journey came to a close on Sunday in Cape Town, South Africa and I hope they got out of it a new appreciation for Darwin. Personally I think you can get more for you money if you read his works, listen to expert opinions and develop your own opinions. The beauty of this is that most of it can be done from the comfort of your own home and when you get the chance to travel, you can trust that Darwin will be everywhere you look.
I´m sure when you were younger your mother sighed exasperatedly "that´s why some animals eat their young" but Marion Mehlis of the University of Bonn in Germany has proven that the three spined Stickleback makes very precise decisions when it comes to eating its offspring. Mehlis concluded that male Sticklebacks that guard the eggs after fertilization eat only the eggs that are fertilized by another male. Sticklebacks are notorious for "sneak fertilizations" but apparently the males have evolved a sense of whose eggs are whose. Researchers speculate that the fish must use some type of odor to determine his own eggs when the paternal genes are activated during development.
The study replaced different percentages of the clutches of male Sticklebacks, including 100% of the eggs, and every time, the male ate all the eggs that he did not fertilize. This goes back to the idea of fitness, in which an animal´s ability to produce more offspring and leave behind more of its genome is the ultimate goal. The fish would be wasting valuable energy and time raising offspring with another competitor´s genes. Darwin, of course, is the father of the "survival of the fittest.
New York Times
I have always seen the debate in the United States between Evolutionists and Creationists as another one of the many battles between the Red and Blue States. My perception was that only the conservative, fundamentalist Christians were the driving force behind the Creationist movement and that it was only in states where these groups were a strong political force was the credibility of Evolution questioned. This article, however, drastically adjusted my perspective on the issue, because it was a school district in Weston, Connecticut that felt teaching 3rd, 4th and 5th graders about Evolution was too controversial. When I think of conservative strong holds in the U.S., Connecticut does not even enter my radar. What this proved to me is that Evolution is a controversial throughout the country and we cannot only think of this as an issue that only affects a few places. This also makes me think about the future of our country and how we should continue to move forward and create a more educated populace. To do this I think it is very important to educate the youth of this country about Charles Darwin and Evolution. I think disregarding this piece of history, because some people disagree with Evolution, is a great disservice to education, because even if a person disagrees with his findings, Charles Darwin changed the way people thought and that is a lesson that every child should be exposed to.
Full Article: http://www.thehour.com/story/485043
Charles Darwin meticulously spelled out the Theory of Evolution in his most famous book, On the Origin of Species (1859). It was the first book on the subject of Evolution that presented the material in a clear and accessible manner that enabled not only scientists, but also the general educated populace to understand Evolution. 150 years later, however, Michael Keller and Nicolle Rager Fuller are helping to make Darwin’s masterpiece accessible to even more people by presenting the information in the form of a graphic novel. This medium is especially powerful for this book, because it was through seeing the world that Darwin was able to develop his Theory on Evolution. Presenting the material in this new and interesting way will help to bring Darwin’s research to the next generation and will hopefully inspire them through its words and images that Evolution is process by which the world has formed. It should also be noted that I stumbled upon this book, because of how well made it was, being recognized within the graphic novel community with a 2010 Eisner Award Nomination for Best Adaptation of Another Work.
Full Article about Eisner Awards: http://www.comic-con.org/cci/cci_eisners_10nom.php
Link to More Information about Charles Darwin´s On the Origin of Species: A Graphic Adaptation: http://www.amazon.com/Charles-Darwins-Origin-Species-Adaptation/dp/160529697X
Charles Darwin’s research on the connection between the face and emotion was presented in, The Expression of the Emotions in Man and Animals (1872). This was a revolutionary concept, but at the time it was published it went relatively unnoticed and since then has been lost in history among his other marvelous contributions to science. Emotional expressions, however, have recently caught the attention of researches throughout the U.S. as they examine emotions with respect to people who have been born with facial paralysis. The interest begins, because leading studies have shown that facial mimicry is what allows people to interpret each other’s emotions, while a person with facial paralysis is not able to interact in this way. This explains why a person with facial paralysis would struggle interacting in the “normal” manner, because the people they are interacting with feel disconnected from them, because they cannot determine the person’s emotions. People with facial paralysis, however, are just as good as people without it at identifying emotions, which proves that there is some other mechanism that a person can use to identify emotions other than facial mimicry. Scientists hope to apply this discover to helping people who suffer from conditions such as autism, which make them unable to determine facial cues. Their thought process is that if they can figure out how to teach someone to use this other mechanism of identification of emotions, then they will be able to teach these people how to emotionally connect with the world.
miércoles, 21 de abril de 2010
martes, 20 de abril de 2010
Charles Darwin´s "The Origin of Species", first published in 1859, has been called the biggest single idea in the history of thought.
This is the story of how it came to written.
This is the opening of the film "Creation", which is going to be released to DVD June 16th. This film created quite a bit of controversy as it tackled Creationism and Evolution as opposing sides in a black and white battle of right and wrong. I watched this film online and took a few notes about interesting scenes. Also, there are a few interpretations/ artistic liscense abuses that give the movie its drama. However, this film brings Darwin back to the front of a mainstream audience. It had difficulties finding a distributor within the United States, but was eventually picked up by Newmarket Films, the same distributor that released "The Passion of the Christ" in the U.S.
If anybody would like to watch the movie, here is the link: