Getty Images/WireImage
I am predicting that The Economist will carry an obituary.
Friday, January 8, 2010
We All Need A Little Luck In Life
From Discovery News:
Tsutomu Yamaguchi, the only person officially recognized as a survivor of both the Hiroshima and Nagasaki atomic bombings at the end of World War II, has died at age 93....
Getty Images/WireImage
I am predicting that The Economist will carry an obituary.
Getty Images/WireImage
I am predicting that The Economist will carry an obituary.
Thursday, January 7, 2010
Tasmanian Devils And One Selfish Gene
Genes don't have real motives. Selfish in the term "selfish gene" really reflects the metaphorical motives of genes and not the real motives of individuals carrying those genes.
Ordinarily, different genes in the multicellular bodies of organisms co-operate. Such a system has evolved because in sexually reproducing multicellular organisms the reproductive fate of any gene depends on the successful reproduction of the individual. Genes in the somatic cells of the body, cells which form the body mass, can extend their lives only if a copy of themselves in the sex cells gets passed on. Co-operating to build successful bodies is the only way out.
But what if a gene is able bypass this system? What if a gene is able to unlink its reproduction from the reproduction of the individual?
Just such a situation has occurred in the spread of cancerous facial tumor in populations of the Tasmanian Devil - a carnivorous marsupial. Scientists working on these animals have identified a nerve cell type known as Schwann cells as the progenitor of this cancer which must have originated through mutations in one Schwann cell of one individual Tasmanian Devil.
Devils are aggressive creatures and they often bite each other especially during mating. The cancer cells graft themselves on facial tissue of the other individual and grow and spread. As cells divide, the bodies defense may kill some of these cells, but mutants among them which are better able to resist thus become more common. This is natural selection acting on this cell lineage. Within the lifetime of an individual devil, cancer cells divide hundreds of times. Cells in the nth generation would be different somewhat from their ancestral state. This is evolution, though not in the form we are familiar with or think of commonly. Ordinarily, this cancer cell lineage would die with the death of the individual. In this case, their evolution continues when they get grafted on another individual. The tumor gene thus spreads through the population by bypassing the normal channels of reproduction. The cancer cells have been able to successfully invade another body in this way because there is very little genetic variation in the immune system of the Tasmanian Devils. That may be because there are a small inbred population. Immune cells don't recognize grafted cancer cells as foreign and don't reject them.
The mutant gene (s) responsible for this cancer can be thought of as a special type of a selfish gene. In a broader sense all genes are selfish since they "try" to maximize copies of themselves by competing against variations of themselves. Generally, the reproductive fate of the gene is tied to the reproductive fate of the individual and so genes cooperate to make bodies successful. However, in the more specific usage of the term, selfish genes may enhance their own reproduction by subverting the reproductive machinery of the cell and in the process causing harm to the population in the long run. During sexual reproduction any gene on average has a fifty percent chance of being passed on to the next generation. A selfish gene subverts these odds and ensures a more than even chance for copies of itself to be passed on.
In the case of the Tasmanian Devils, the "selfish gene" is not in the sex cells but is a somatic cell mutant.
We don't think of somatic cells as a separate life form. The cells that make up our bodies are us. But occasionally as in the case of the facial cancer in the Tasmanian Devils the us can morph into the other. Most cancerous cell types which rebel against the body don't have an extended evolutionary future. The cell lineage dies with the death of the individual. This particular cancer cell however, which was once part of the Tasmanian Devil is evolving into a parasite. It has developed a life of its own.
This situation illustrates several broader principles of evolution.
Firstly that evolution has no foresight. There is no long term benefit of the Tasmanian Devils that evolution is striving towards. Natural selection doesn't work for the benefit of the species. Evolution through natural selection is all about immediate advantage. Mutant cells have found a way to propagate independent of the body and because their life cycles operate quicker than that of an individual, selection will favor the spread of these cells regardless of whether that is harming Devil individuals and populations.
Second, it demonstrates that natural selection doesn't only act at the level of the individual. It can act on any entities which shows certain properties. If entities vary in certain traits, if these traits are heritable and if these traits affect "fitness" i.e. they enable one variant to reproduce more than the other then natural selection is off and running. In the natural world these conditions are most familiarly met by whole organisms but in principal they can be met by cells or genes within cells.
In this case, selection is operating at two levels. At a lower level cells which contain the mutant gene are fitter than cells that don't contain this gene. But at a higher level individuals that don't contain this mutant gene are fitter than individuals that do. In most cases the "interests" of the gene and the individual coincide. Here, because their reproductive fates have been decoupled the relationship has turned antagonistic.
Finally, the study shows that the reconstruction of a complete evolutionary narrative requires thinking across the entire (or as much as possible) hierarchy of life. The so called division between reductionists and practitioners of "holistic" biology is and always has been a false dichotomy. Genes, cells, individuals, social behavior and population history all go to make the unfortunate story of the Tasmanian Devils more complete.
** Wishing readers coming to this post via Desipundit a very Happy New Year. If you missed my earlier announcement do note that my blog Reporting on a Revolution has been renamed Rapid Uplift. ...more in tune with the broad earth sciences / geology theme I write about. Thanks for your support.
Ordinarily, different genes in the multicellular bodies of organisms co-operate. Such a system has evolved because in sexually reproducing multicellular organisms the reproductive fate of any gene depends on the successful reproduction of the individual. Genes in the somatic cells of the body, cells which form the body mass, can extend their lives only if a copy of themselves in the sex cells gets passed on. Co-operating to build successful bodies is the only way out.
But what if a gene is able bypass this system? What if a gene is able to unlink its reproduction from the reproduction of the individual?
Just such a situation has occurred in the spread of cancerous facial tumor in populations of the Tasmanian Devil - a carnivorous marsupial. Scientists working on these animals have identified a nerve cell type known as Schwann cells as the progenitor of this cancer which must have originated through mutations in one Schwann cell of one individual Tasmanian Devil.
Devils are aggressive creatures and they often bite each other especially during mating. The cancer cells graft themselves on facial tissue of the other individual and grow and spread. As cells divide, the bodies defense may kill some of these cells, but mutants among them which are better able to resist thus become more common. This is natural selection acting on this cell lineage. Within the lifetime of an individual devil, cancer cells divide hundreds of times. Cells in the nth generation would be different somewhat from their ancestral state. This is evolution, though not in the form we are familiar with or think of commonly. Ordinarily, this cancer cell lineage would die with the death of the individual. In this case, their evolution continues when they get grafted on another individual. The tumor gene thus spreads through the population by bypassing the normal channels of reproduction. The cancer cells have been able to successfully invade another body in this way because there is very little genetic variation in the immune system of the Tasmanian Devils. That may be because there are a small inbred population. Immune cells don't recognize grafted cancer cells as foreign and don't reject them.
The mutant gene (s) responsible for this cancer can be thought of as a special type of a selfish gene. In a broader sense all genes are selfish since they "try" to maximize copies of themselves by competing against variations of themselves. Generally, the reproductive fate of the gene is tied to the reproductive fate of the individual and so genes cooperate to make bodies successful. However, in the more specific usage of the term, selfish genes may enhance their own reproduction by subverting the reproductive machinery of the cell and in the process causing harm to the population in the long run. During sexual reproduction any gene on average has a fifty percent chance of being passed on to the next generation. A selfish gene subverts these odds and ensures a more than even chance for copies of itself to be passed on.
In the case of the Tasmanian Devils, the "selfish gene" is not in the sex cells but is a somatic cell mutant.
We don't think of somatic cells as a separate life form. The cells that make up our bodies are us. But occasionally as in the case of the facial cancer in the Tasmanian Devils the us can morph into the other. Most cancerous cell types which rebel against the body don't have an extended evolutionary future. The cell lineage dies with the death of the individual. This particular cancer cell however, which was once part of the Tasmanian Devil is evolving into a parasite. It has developed a life of its own.
This situation illustrates several broader principles of evolution.
Firstly that evolution has no foresight. There is no long term benefit of the Tasmanian Devils that evolution is striving towards. Natural selection doesn't work for the benefit of the species. Evolution through natural selection is all about immediate advantage. Mutant cells have found a way to propagate independent of the body and because their life cycles operate quicker than that of an individual, selection will favor the spread of these cells regardless of whether that is harming Devil individuals and populations.
Second, it demonstrates that natural selection doesn't only act at the level of the individual. It can act on any entities which shows certain properties. If entities vary in certain traits, if these traits are heritable and if these traits affect "fitness" i.e. they enable one variant to reproduce more than the other then natural selection is off and running. In the natural world these conditions are most familiarly met by whole organisms but in principal they can be met by cells or genes within cells.
In this case, selection is operating at two levels. At a lower level cells which contain the mutant gene are fitter than cells that don't contain this gene. But at a higher level individuals that don't contain this mutant gene are fitter than individuals that do. In most cases the "interests" of the gene and the individual coincide. Here, because their reproductive fates have been decoupled the relationship has turned antagonistic.
Finally, the study shows that the reconstruction of a complete evolutionary narrative requires thinking across the entire (or as much as possible) hierarchy of life. The so called division between reductionists and practitioners of "holistic" biology is and always has been a false dichotomy. Genes, cells, individuals, social behavior and population history all go to make the unfortunate story of the Tasmanian Devils more complete.
** Wishing readers coming to this post via Desipundit a very Happy New Year. If you missed my earlier announcement do note that my blog Reporting on a Revolution has been renamed Rapid Uplift. ...more in tune with the broad earth sciences / geology theme I write about. Thanks for your support.
Tuesday, January 5, 2010
Hydrologist Will Be One Of Top Careers In 2010
US News and World Report has a listing of best science and technology careers and hydrologists figures among the top.
The figures are for the United States but I would predict that a career to do with water holds a lot of promise in any country. This is not a new observation. Sometime back Science Careers carried a lengthy article on hydrogeology careers and called them "recession proof".
Population pressures, water reallocation challenges between rural and urban consumers, climate change and past mismanagement of water resources means there will be plenty of work for hydrologists and hydrogeologists for decades to come.
Job opportunities should be plentiful for environmental scientists and especially for hydrologists. There were 8,100 hydrologist jobs in 2008, and employment should grow more than 18 percent by 2018. The government has stepped up environmental regulations and has begun cleaning up contaminated and hazardous waste sites—all efforts that increase the need for hydrological research. Competition for openings is limited by the small number of universities and colleges that offer degrees in hydrology.
The figures are for the United States but I would predict that a career to do with water holds a lot of promise in any country. This is not a new observation. Sometime back Science Careers carried a lengthy article on hydrogeology careers and called them "recession proof".
Population pressures, water reallocation challenges between rural and urban consumers, climate change and past mismanagement of water resources means there will be plenty of work for hydrologists and hydrogeologists for decades to come.
Now That's An Earthquake Cluster
From my USGS magnitude 5+ earthquake feed:
Begining with a foreshock of mag 6.5, a bigger shock of 7.2 and then a series of aftershocks of 5+; all within several hours of immense rumbling and shaking in the Solomon islands at the junction of the Australian plate and the Pacific plate. In the map below the plate boundary trends NW-SE just south of the islands.
Here is the tectonic summary from USGS:
Begining with a foreshock of mag 6.5, a bigger shock of 7.2 and then a series of aftershocks of 5+; all within several hours of immense rumbling and shaking in the Solomon islands at the junction of the Australian plate and the Pacific plate. In the map below the plate boundary trends NW-SE just south of the islands.
Here is the tectonic summary from USGS:
The Solomon Islands earthquake of January 3, 2010, likely occurred
at the boundary between the Pacific and Australian plates, where the
Australian plate subducts beneath the Pacific towards the northeast at
a rate of approximately 95 mm/yr. The mechanism of the January 3rd
earthquake is consistent with its occurrence in relation to
underthrusting of the Australia plate beneath the Pacific plate, as
part of this subduction process.
The Solomon Islands arc as a whole experiences a very high level of
earthquake activity, and many shocks of magnitude 7 and larger have
been recorded since the early decades of the twentieth century. The
January 3rd, 2010 earthquake nucleated approximately 50 km to the
southeast of a M8.1 earthquake in April 2007, which with an associated
tsunami caused at least 50 fatalities and destroyed several coastal
villages on nearby islands. An M6.5 foreshock occurred less than one
hour before this main shock, in approximately the same location.
Monday, January 4, 2010
Reporting on a Revolution Has Been Renamed Rapid Uplift
I got me a new blog name this new year. In a civil ceremony Reporting on a Revolution has been rechristened Rapid Uplift.
I think the new name has a restless dynamic geologyey feel to it. It is more in tune with the broad theme of my blog of a changing planet..being reshaped and re sculpted through geological processes and biological evolution. I have to admit that the focus of this blog has changed somewhat over the last two years. My initial purpose of keeping a tab on poor and sensationalistic science reporting especially by the Indian media prompted the blog title Reporting on a Revolution.
Over time though I have found myself writing more and more on geology related themes often not taking cues from media reports or without any intent to criticize media reporting but writing simply because I found a particular story interesting.
Rapid Uplift will continue this geology centered science outreach attempt.
Do update your blogrolls. The page and feed URLs are unchanged.
Wishing everyone a Happy New Year!
I think the new name has a restless dynamic geologyey feel to it. It is more in tune with the broad theme of my blog of a changing planet..being reshaped and re sculpted through geological processes and biological evolution. I have to admit that the focus of this blog has changed somewhat over the last two years. My initial purpose of keeping a tab on poor and sensationalistic science reporting especially by the Indian media prompted the blog title Reporting on a Revolution.
Over time though I have found myself writing more and more on geology related themes often not taking cues from media reports or without any intent to criticize media reporting but writing simply because I found a particular story interesting.
Rapid Uplift will continue this geology centered science outreach attempt.
Do update your blogrolls. The page and feed URLs are unchanged.
Wishing everyone a Happy New Year!
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