Friday, April 25, 2008

Could Humans Have Faced a Near Extinction 70,000 Years Ago?

An extensive genetic study is suggesting that human beings may have had a brush with extinction 70,000 years ago. The human population at that time was reduced to very small and isolated groups on the African Continent, most likely due to intense drought conditions, according to an analysis released Thursday. The report also notes that a separate study by researchers at Stanford University estimated the number of early humans may have been reduced to as low as 2,000 before numbers began to expand in the early Stone Age.

"This study illustrates the extraordinary power of genetics to reveal insights into some of the key events in our species' history," Spencer Wells, National Geographic Society explorer in residence, said in a statement. "Tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA."

Wells is director of the Genographic Project, launched in 2005 to study anthropology using genetics. The report was published in the American Journal of Human Genetics. Previous studies using mitochondrial DNA, which is passed down through mothers, have traced modern humans to a single "mitochondrial Eve," who lived in Africa about 200,000 years ago.

The migrations of humans out of Africa to populate the rest of the world appear to have begun about 60,000 years ago, but little has been known about humans between Eve and that dispersal. The new study looks at the mitochondrial DNA of the Khoi and San people in South Africa which appear to have diverged from other people between 90,000 and 150,000 years ago.

The researchers led by Doron Behar of Rambam Medical Center in Haifa, Israel and Saharon Rosset of IBM TJ Watson Research Center in Yorktown Heights, NY, and Tel Aviv University concluded that humans separated into small populations prior to the Stone Age, when they came back together and began to increase in numbers and spread to other areas.

Eastern Africa experienced a series of severe droughts between 135,000 and 90,000 years ago and the researchers said this climatological shift most likely contributed to the population changes, dividing into small, isolated groups which developed independently. Paleontologist Meave Leakey, a Genographic adviser, commented: "Who would have thought that as recently as 70,000 years ago, extremes of climate had reduced our population to such small numbers that we were on the very edge of extinction."

Today more than 6.6 billion people inhabit the globe, according to the US Census Bureau. The research was funded by the National Geographic Society, IBM, the Waitt Family Foundation, the Seaver Family Foundation, Family Tree DNA and Arizona Research Labs.

Monday, April 7, 2008

Centralia, Pennsylvania a town on fire since 1962

Johnathan Faust opened Bull's Head Tavern in 1841 in what was then Roaring Creek Township. In 1854, Alexander W. Rea, a civil and mining engineer for the Locust Mountain Coal and Iron Company, moved to the site and laid out streets and lots for development. The town was known as Centreville until 1865, when the post office was established and the name was changed to Centralia. Centralia was incorporated as a borough in 1866. The anthracite coal industry was the principal employer in the community. Coal mining continued in Centralia until the 1960s, when most of the companies went out of business. Bootleg mining continued until 1982. Strip and open-pit mining is still active in the area, and there is an underground mine employing about 40 employees three miles to the west.

The borough was served by two railroads, the Philadelphia and Reading and the Lehigh Valley, with the Lehigh Valley being the principal carrier. Rail service ended in 1966. The borough operated its own school district with elementary schools and a high school within its precincts. There were also two Catholic parochial schools in the borough. The borough once had seven churches, five hotels, twenty-seven saloons, two theatres, a bank, post office, and fourteen general and grocery stores. During most of the borough's history, when coal mining activity was being conducted, the town had a population in excess of 2,000 residents. Another 500 to 600 residents lived in unincorporated areas immediately adjacent to Centralia.

Mine fire
In May 1962, Centralia Borough Council hired five members of the volunteer fire company to clean up the town landfill, located in an abandoned strip mine pit next to the Odd Fellows Cemetery. This had been done prior to Memorial Day in previous years, but in previous years the landfill was in a different location. The firemen, as they had in the past, set the dump on fire, let it burn for a time, and then extinguished the fire. However, the fire was not extinguished.

In her 2007 book about Centralia, Joan Quigley asserts that the fire began on May 27 when one of the two commercial haulers serving the borough "hurled hot ashes onto the dump." Quigley cites "interviews with volunteer firemen, the former fire chief, borough officials, and several eyewitnesses, as well as contemporaneous borough council minutes" as her sources for this explanation of the fire.

The fire remained burning in the lower depths of the garbage and eventually spread through a hole in the rock pit into the abandoned coal mines beneath Centralia. Attempts to extinguish the fire were unsuccessful, and it continued to burn throughout the 1960s and 1970s. Adverse health effects were reported by several people due to the carbon monoxide produced.

Where PA Route 61 Cuts off due to the Mine FireIn 1979, locals became aware of the scale of the problem when a gas station owner inserted a stick into one of his underground tanks to check the fuel level. When he withdrew it, it seemed hot, so he lowered a thermometer down on a string and was shocked to discover that the temperature of the gasoline in the tank was 172 °F (77.8 °C). Statewide attention to the fire began to increase, culminating in 1981 when 12 yr old Todd Domboski fell into a sinkhole four feet wide by 150 feet (46 m) deep that suddenly opened beneath his feet. He was saved after his older cousin pulled him from the mouth of the hole before he could plunge to his probable death. The incident brought national attention to Centralia as an investigatory group (including a state representative, a state senator, and a mine safety director) were coincidentally on a walking tour of Domboski's neighborhood at the time of his near-death incident.

Section of PA Route 61 closed due to mine fire.In 1984, Congress allocated more than $42 million for relocation efforts. Most of the residents accepted buyout offers and moved to the nearby communities of Mount Carmel and Ashland. A few families opted to stay despite warnings from state officials.

In 1992, Pennsylvania claimed eminent domain on all properties in the borough, condemning all the buildings within. A subsequent legal effort by residents to have the decision reversed failed. In 2002, the United States Postal Service revoked Centralia's ZIP code, 17927.

A 1999 photo showing the abandoned highway, and its replacementA handful of occupied homes remain in Centralia. Most of the buildings have been razed, and at a casual glance the area now appears to be a meadow with several paved streets through it. Some areas are being filled with new-growth forest. Most of Centralia's roads and sidewalks are overgrown with brush, although some areas appear to be mowed. The remaining church in the borough holds weekly Saturday night services, and the borough's four cemeteries are still well-maintained. Centralia's cemeteries now have a far greater population than the town, including one on the hilltop that has smoke rising around and out of it.

The only indications of the fire, which underlies some 400 acres, spreading along four fronts, are low round metal steam vents in the south of the borough, and several signs warning of underground fire, unstable ground, and carbon monoxide. Additional smoke and steam can be seen coming from an abandoned portion of Pennsylvania Route 61, the area just behind the hilltop cemetery, and various other cracks in the ground scattered about the area. Route 61 was repaired several times until its final closing. The current route was a detour around the damaged portion during the repairs and became a permanent route in the mid 90's, thus abandonment occurred to the old route with permanent barriers being placed at both ends of the former route. However, the underground fire is still burning and will continue to do so for the indefinite future. There are no current plans to extinguish the fire, which is consuming an eight mile seam containing enough coal to fuel it for 250 years.

Sunday, April 6, 2008

The Battle of Hastings 1066

When Edward the Confessor died he left no direct heir, and the throne of England passed to Harold. However, William of Normandy claimed that Edward had promised the crown to him, and indeed that Harold himself had sworn a sacred oath to relinquish his claim in William's favour. William prepared an invasion fleet and, armed with a papal bull declaring his right to the throne, he crossed the English Channel to land near Pevensey.

Harold , in the meantime, had another threat to concern him; his brother Tostig allied with Harald Hardrada of Norway and landed in the north of England. They took York, but Harold defeated them soundly at the Battle of Stamford Bridge. No sooner had the battle dust settled than Harold received news of William's invasion in the south. He marched his tired men from York to Sussex, arriving there on October 13 to face the Normans.

The battle took place on October 14, 1066. Harold and the English army took up a defensive position on a high ridge known as Senlac. The battle began with devastating volleys of stone missiles hurled into the Norman infantry by the Saxon "fyrd", or irregular troops levied from the shires. William himself led the centre of the Norman army, and it is said that he carried into battle some of the holy relics upon which Harold had sworn to cede the crown to him.

The Norman infantry made no dent in the Saxon lines, and the cavalry fared no better. But when some of the Norman horsemen turned and fled, a large group of Saxons left their position to chase them. It was a fatal mistake, as William rallied his men and routed the unprotected attackers. The Saxon lines quickly closed, but they had not learned their lesson, and they repeated the same folly of chasing an apparently fleeing enemy twice more as the day wore on. By late afternoon the Saxon lines were wavering under continued Norman attacks. It is then that the most famous arrow in English history was released by an anonymous Norman archer. The arrow took King Harold in the eye, and a final Norman onslaught killed him where he stood. The rest of the leaderless Saxons ceded Senlac ridge yard by grudging yard, but eventually they had no choice but to turn and flee the field. The day belonged to Duke William, soon to be dubbed, "the Conqueror". The body of King Harold was eventually buried in Waltham Abbey.

The Battle of Hastings was the decisive Norman victory in the Norman Conquest of England. Although there were sporadic outbreaks of Saxon resistance to Norman rule after the Battle of Hastings, notably in East Anglia under Hereward the Wake, and in the north of England, from this point on England was effectively ruled by the Normans.