I wrote this post for the blog I write for a course, Peoples and Cultures of the World, and originally intended it primarily for a student audience. However, I think it fits well here as well.
“Possible,” “Plausible,” “Probable,” and “Proven” are terms used to indicate rough degrees of statistical probability of something happening or some proposition being true. (My use of the “probable” here reflects the vernacular. When we say that something is probably true, we don’t mean that it has just any level of statistical probability, but specifically that it is quite likely to be true.)
The terms do reflect an ascending order of probability (and a nested one – anything that is plausible is also possible; anything proven is also probable, plausible, and possible), though not in a numerically precise way. They represent a sort of qualitative statistics. When we can realistically indicate precise probabilities, that is obviously a useful thing, but even a rough sense of degree of probability is far more useful than no such sense at all.
Errors in thinking arise whenever we jump up this ascending ladder of probability without evidence, or without sufficient evidence (though admittedly, knowing what counts as sufficient evidence is always tricky business). Just because it’s possible that Bigfoot could be running around the Pacific Northwest or elsewhere doesn’t make it plausible, much less probable or proven.
The Possible
Saying that something is possible simply means that it does not violate the basic laws of logic. In the realm of empirical scholarship, one could also add that it does not violate basic physical laws, that something is both logically and physically possible.
The existence of Bigfoot is possible – it violates no logical or physical rules, but given the overwhelming lack of evidence, there’s no reason to regard Bigfoot’s existence as having anything but the lowest degree of probability. The same goes for claims about extraterrestrial influence in building the Egyptian Pyramids or Stonehenge or the Nazca Lines.
The Plausible
To say that something is plausible is to indicate that it has a higher probability than the merely possible - it is believable, it makes sense. But claims that are merely plausible (that is, that are not also probable) lack the evidence to be taken as having a high degree of probability of truth.
Thor Heyerdahl’s famous voyage on his Kon-Tiki raft from South America to Polynesia certainly proved that it was possible for people to have traveled from the one place to the other using fairly simple watercraft. He even made it plausible that Polynesians could have made voyages to South America, but his voyage alone did nothing to make such notions probable, much less proven. (See this news article from this past summer from Live Science on both Heyerdahl and more recent evidence of Polynesian voyaging to South America that I’ll discuss below.)
An article I encountered this morning on Science Daily, “Early Apes Walked Upright 15 Million Years Earlier Than Previously Thought, Evolutionary Biologist Argues,” makes what I’d consider a plausible claim. “An extraordinary advance in human origins research reveals evidence of the emergence of the upright human body plan over 15 million years earlier than most experts have believed. More dramatically, the study confirms preliminary evidence that many early hominoid apes were most likely upright bipedal walkers sharing the basic body form of modern humans.” So long as there’s evidence, it’s plausible that hominoid bipedalism might be much older than previously thought, but this is an extraordinary claim, and as such requires not simply a single study with good evidence, but a body of good evidence in order to be taken as probable, much less proven by many scholars.
The Probable and the Proven
To say that something is probable means that it is very likely to be the case, that it has a high degree of probability. To refer to something as proven implies that a claim is definitely true, though given the ever present possibilities of faulty observation (even systematic faulty observation), partial understanding or misunderstanding of empirical materials, nothing (at least outside the abstract realm of pure logic and mathematics) is ever demonstrated to be completely and irrevocably true. Instead, to say something is proven is really to say that it has such a high degree of probability of truth that we can pragmatically assume it to be true (though ideally keeping an open mind towards potential counter-evidence).
When Pizarro and his Spanish soldiers reached Peru, they encountered chickens (an Old World domesticated bird) already there. There are at least a couple ways the chickens could have arrived in the New World – they could have been brought by the very earliest European voyages to the Caribbean and Central America in the 1490s and 1500s and very rapidly diffused southward; or they could have been brought by Polynesian voyagers to South America (the only problem there being, at least until now, a lack of evidence of such Polynesian voyages having actually occurred).
When Captain Cook and other explorers encountered a variety of Polynesian islands in the late 18th century, they encountered sweet potatoes, among other crops being grown. As I understand it, there’s no definite evidence of how these South American plants reached Polynesia. They could have been brought by the Spanish to the Philippines early in the Colonial period and diffused from there to Indonesia, Melanesia, and ultimately Polynesia, or they could have been brought back from South America by Polynesians themselves.
New evidence released this past summer addresses this situation. Chicken bones were recovered in Peru that, according to carbon dating, predate Spanish voyages to the Americas by about a century. Further, genetic evidence links the chicken bones to Polynesian varieties of chickens. (See the previously cited article from Live Science and also this article from New Scientist.)
If the carbon dating and DNA evidence hold up (always an important consideration with important new claims), this proves that Polynesian chickens reached Peru at least on one occasion. Given the highly implausible nature of chickens making the voyage on their own (though not logically impossible), it makes highly probable if not proving claims that Polynesians came to South America on at least one occasion. It makes highly probable that the chickens seen by Pizarro were of Polynesian stock as well. I’d even go so far as to say that this new evidence makes probable the idea that Polynesians brought sweet potatoes back from South America directly, though the distinction between plausible and probable is a bit more ambiguous in this case.
Showing posts with label bipedalism. Show all posts
Showing posts with label bipedalism. Show all posts
Thursday, October 11, 2007
Monday, July 30, 2007
A Round-Up of Recent News and Articles of Interest
Genocide
Asia Times has published a provocative essay by Spengler, “In Defense of Genocide, Redux.” As with Spengler’s earlier essay, “In Defense of Genocide,” this is not actually a defense of genocide, but an essay about the shocking extent to which genocide and potential genocide is denied, ignored, or rationalized away as essentially inconsequential by much of the media, and many policy makers, politicians, and political candidates (see, for example, Barack Obama’s recent comments that genocide would not be a good reason for U.S. troops to remain in Iraq – to me, that would be the one good reason for U.S. troops to remain there – if independent, credible evidence indicated that U.S. troops leaving would result in genocide and that U.S. troops remaining would prevent it).
Anti-Smoking Campaigns and Social Norms Marketing
A recent article on Medical News Today about a study of anti-smoking campaigns targeting youth, “The Secret of Successful Anti-Smoking Ads,” seems to me to give weight to “social norms marketing” strategies (or at least to something similar to them) used by some sociologists, psychologists and others involved with public health education and behavior change campaigns. Social norms marketing tends to emphasize what is “normal” behavior for a target population, the idea being that most people who identify with a particular group want to fit in with their peer group (i.e. social norms marketing is really a form of “enlightened peer pressure).
The following is from the article:
"Some anti-smoking ads are simply ineffective, while others actually make youth more likely to light up. Fortunately, some are successful, and a new University of Georgia study helps explain why.
"Hye-Jin Paek, assistant professor at the UGA Grady College of Journalism and Mass Communication, found that anti-smoking ads are most effective when they convince youth that their friends are listening to the ads. Otherwise, the ads appear to stimulate the rebellious and curious nature of youth, making them more interested in smoking. Paek and co-author Albert Gunther from the University of Wisconsin-Madison examined data from surveys of nearly 1,700 middle school students, and their results appear in the August issue of the journal Communication Research."
Race and Medical Care
“When it comes to medical care – skin color matters” reports on a study indicating that, at least in a carefully constructed simulated exercise, race can affect the quality of medical care received.
The following is from the article:
“Other studies too have found that whites receive better medical care than blacks and experts agree the information is not new.
“But this one differs in that it is the first to demonstrate the reason for the difference really is racial bias.
“Following their evaluation of the two simulated patients, the doctors were then given an 'implicit association test' designed to reveal a person's unconscious views of blacks and whites.
“Dr. Green says a high score on the bias against African-Americans portion of the test, showed doctors were less likely to provide clot-busting treatment for a heart attack for black patients.”
The Rise and Fall of Woolworth
“Why Woolworth Had to Die” provides a short synopsis of the rise and decline of the Woolworth’s retail chain over the 20th century, but more interestingly, the article provides a decent short overview of changes in communities and marketing over the course of the century in the U.S.
Drugs, Organized Crime, Development, and Journalism in Africa and Mexico
Two recent articles at AllAfrica.com present a troubling picture of recent developments in Sub-Saharan Africa. “Organized Crime Targets Weak States,” presents an overview of recent moves by organized crime, especially syndicates associated with drug smuggling – in particular the movement of cocaine from South America into Europe, to increasingly take up shop in weak states of Sub-Saharan Africa. The article also discusses some of the debilitating effects this can have on economic development, as if the people of Sub-Saharan African nations needed other economic obstacles.
“IFJ condemns threats against two journalists covering drug trafficking,” as its title indicates, covers recent threats made by traffickers against journalists who cover the drug trade with any depth. This presents a troubling parallel with the recent spate of drug-related violence in general, and specifically violence directed against journalists covering the drug trade, in Mexico. For example, see the article “Drug Wars Endanger Mexican Press.”
Chimpanzees and Bipedalism
There has been much in the realm of anthropology news and blogs recently about origins of bipedalism. An article, “Study Sheds Light on Bipedal Walking” at Medical News Today covering a recent study of energetics of upright walking among chimpanzees presents some interesting information.
The following three paragraphs are from the article:
"We were prepared to find that all of the chimps used more energy walking on two legs -- but that finding wouldn't have been as interesting," Sockol said. "What we found was much more telling. For three chimps, bipedalism was more expensive, but for the other two chimps, this wasn't the case. One expended about the same energy walking on two legs as on four. The other used less energy walking upright."
These two chimps had different gaits and anatomy than their knucklewalking peers. And when the researchers examined the early hominid fossil record, they found evidence of these traits -- skeletal characteristics of the hip and hind limb that allow for greater extension of the hind limb -- in some early bipeds.
Taken together, the findings provide support for the hypothesis that anatomical differences affecting gait existed among our earliest apelike ancestors, and that these differences provided the genetic variation natural selection could act on when changes in the environment gave bipeds an advantage over quadrupeds.
Asia Times has published a provocative essay by Spengler, “In Defense of Genocide, Redux.” As with Spengler’s earlier essay, “In Defense of Genocide,” this is not actually a defense of genocide, but an essay about the shocking extent to which genocide and potential genocide is denied, ignored, or rationalized away as essentially inconsequential by much of the media, and many policy makers, politicians, and political candidates (see, for example, Barack Obama’s recent comments that genocide would not be a good reason for U.S. troops to remain in Iraq – to me, that would be the one good reason for U.S. troops to remain there – if independent, credible evidence indicated that U.S. troops leaving would result in genocide and that U.S. troops remaining would prevent it).
Anti-Smoking Campaigns and Social Norms Marketing
A recent article on Medical News Today about a study of anti-smoking campaigns targeting youth, “The Secret of Successful Anti-Smoking Ads,” seems to me to give weight to “social norms marketing” strategies (or at least to something similar to them) used by some sociologists, psychologists and others involved with public health education and behavior change campaigns. Social norms marketing tends to emphasize what is “normal” behavior for a target population, the idea being that most people who identify with a particular group want to fit in with their peer group (i.e. social norms marketing is really a form of “enlightened peer pressure).
The following is from the article:
"Some anti-smoking ads are simply ineffective, while others actually make youth more likely to light up. Fortunately, some are successful, and a new University of Georgia study helps explain why.
"Hye-Jin Paek, assistant professor at the UGA Grady College of Journalism and Mass Communication, found that anti-smoking ads are most effective when they convince youth that their friends are listening to the ads. Otherwise, the ads appear to stimulate the rebellious and curious nature of youth, making them more interested in smoking. Paek and co-author Albert Gunther from the University of Wisconsin-Madison examined data from surveys of nearly 1,700 middle school students, and their results appear in the August issue of the journal Communication Research."
Race and Medical Care
“When it comes to medical care – skin color matters” reports on a study indicating that, at least in a carefully constructed simulated exercise, race can affect the quality of medical care received.
The following is from the article:
“Other studies too have found that whites receive better medical care than blacks and experts agree the information is not new.
“But this one differs in that it is the first to demonstrate the reason for the difference really is racial bias.
“Following their evaluation of the two simulated patients, the doctors were then given an 'implicit association test' designed to reveal a person's unconscious views of blacks and whites.
“Dr. Green says a high score on the bias against African-Americans portion of the test, showed doctors were less likely to provide clot-busting treatment for a heart attack for black patients.”
The Rise and Fall of Woolworth
“Why Woolworth Had to Die” provides a short synopsis of the rise and decline of the Woolworth’s retail chain over the 20th century, but more interestingly, the article provides a decent short overview of changes in communities and marketing over the course of the century in the U.S.
Drugs, Organized Crime, Development, and Journalism in Africa and Mexico
Two recent articles at AllAfrica.com present a troubling picture of recent developments in Sub-Saharan Africa. “Organized Crime Targets Weak States,” presents an overview of recent moves by organized crime, especially syndicates associated with drug smuggling – in particular the movement of cocaine from South America into Europe, to increasingly take up shop in weak states of Sub-Saharan Africa. The article also discusses some of the debilitating effects this can have on economic development, as if the people of Sub-Saharan African nations needed other economic obstacles.
“IFJ condemns threats against two journalists covering drug trafficking,” as its title indicates, covers recent threats made by traffickers against journalists who cover the drug trade with any depth. This presents a troubling parallel with the recent spate of drug-related violence in general, and specifically violence directed against journalists covering the drug trade, in Mexico. For example, see the article “Drug Wars Endanger Mexican Press.”
Chimpanzees and Bipedalism
There has been much in the realm of anthropology news and blogs recently about origins of bipedalism. An article, “Study Sheds Light on Bipedal Walking” at Medical News Today covering a recent study of energetics of upright walking among chimpanzees presents some interesting information.
The following three paragraphs are from the article:
"We were prepared to find that all of the chimps used more energy walking on two legs -- but that finding wouldn't have been as interesting," Sockol said. "What we found was much more telling. For three chimps, bipedalism was more expensive, but for the other two chimps, this wasn't the case. One expended about the same energy walking on two legs as on four. The other used less energy walking upright."
These two chimps had different gaits and anatomy than their knucklewalking peers. And when the researchers examined the early hominid fossil record, they found evidence of these traits -- skeletal characteristics of the hip and hind limb that allow for greater extension of the hind limb -- in some early bipeds.
Taken together, the findings provide support for the hypothesis that anatomical differences affecting gait existed among our earliest apelike ancestors, and that these differences provided the genetic variation natural selection could act on when changes in the environment gave bipeds an advantage over quadrupeds.
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