In 1872, construction workers digging a hole for a fence post near the shores of Lake Winnipesaukee in New England found a lump of clay, with an egg shaped artifact inside it, six feet below the ground. Called the 'Mystery Stone', it is one of New Hampshire's more curious and lesser known relics. Amateur and professional archaeologists have speculated about the origin of this strange artifact for well over one hundred years with no clear answers emerging.

The rock type is not familiar to New Hampshire and there are no other known objects bearing similar markings or design in the United States. It may very have been the work of someone living in a faraway place and time, as nothing like its fine workmanship has been produced by the Native American tribes living locally in the area.

A bullet fragment depicted in an autopsy X-ray used to implicate Lee Harvey Oswald in the assassination of President John F. Kennedy recently has been found to be a faked artifact superimposed on the X-ray sometime after JFK's autopsy.

Such tampering with official evidence could not have been accomplished without the knowledge of high-level federal officials and adds considerable weight to the claims of government cover-up in that tragic event

The X-ray fabrication was the topic of a 2015 paper by Dr. David Dr. Mantik published in issue three of Medical Research Archives, an international scientific peer-reviewed journal publishing articles in all disciplines of medicine, with a focus on new research.

Oswald, an ex-Marine who had attempted to defect to Russia in 1959, was identified in 1964 by President Lyndon B. Johnson's handpicked commission headed by Supreme Court Justice Earl Warren as the lone assassin of President Kennedy. The Warren Commission concluded that Oswald had used a 6.5 mm Italian WWII carbine to shoot Kennedy from the sixth-floor of a book depository building in downtown Dallas on November 22, 1963.

Potentially lethal biological agents were unleashed on an unsuspecting British public and chemical warfare was trialed on military personnel as part of Ministry of Defense (MOD) experiments carried out over decades, a shocking new book reveals.

In his latest work, entitled 'Secret Science: A Century of Poison Warfare and Human Experiments,' University of Kent historian Ulf Schmidt presents a series of case studies about covert state projects conducted between 1939 and 1989.

In one 1953 experiment, 20 year-old Royal Air Force (RAF) engineer Ronald Maddison was killed by exposure to what is now known as sarin gas.

Like many service men of his era, he was promised small amounts of extra pay or days off to take part in the experiment. For 15 shillings and a three-day leave pass, Maddison volunteered.

The mystery surrounding the ancient rock paintings of Utah's Black Dragon Canyon has finally been solved. For decades, researchers and creationists have debated whether the vibrant red pictographs are images of humans and animals, or rather, depictions of a large winged monster, possibly a pterosaur.

Now, using cutting-edge technology, researchers suggest the red paintings show five separate images, including a tall bug-eyed person, a smaller person, a sheep, a dog and a serpentlike figure.

"It is not a single figure. It is not a pterodactyl," said co-lead researcher Paul Bahn, a freelance archaeologist. "It's a beautiful set of images." [See Photos of the Rock Paintings from Black Dragon Canyon]

The rock paintings belong to the agrarian Fremont culture (circa A.D. 1 to 1100). Other Fremont rock paintings — known as Barrier Canyon style — show abstract humanlike figures with elongated bodies and round heads, the researchers wrote in the study.

These long figures are usually accompanied by tiny "attendants," including people, birds and four-legged creatures, such as hoofed animals, canines, felines, badgers and bears.

Amateurs discovered the painting in 1928, and soon after talk of the "winged monster" arose. In 1947, a man named John Simonson traced over the paintings with chalk and said the end result looked like "a weird bird."

Chalking rock art was a common practice in earlier years — ancient rock art is usually faint, and chalk can help make it visible — but today it's illegal, Bahn said.

"It's one of the worst things you can do, because it damages the art, it imposes what you think you can see on it, it messes up the chemistry of the rock, probably, and it just doesn't disappear," Bahn told Live Science.

• Experts say it is 'unlikely' the site still has active pathogens
• Bones of impoverished victims found under highway embankment
• Believed impromptu burial site once been the site of a poorhouse
• Experts say it could contain a mass grave for victims

Researchers have discovered bones believed to be from impoverished victims of the worldwide Spanish flu pandemic in 1918 under a highway embankment in eastern Pennsylvania.

The state highway department, known as PennDOT, received reports of bones in what appeared to be an impromptu burial site beneath a broad meadow that had once been the site of a poorhouse, said Bob Rescorla, a PennDOT inspector at the site.

Researchers are now looking for more bones believed to be from impoverished victims of the worldwide Spanish flu pandemic in 1918.

The state highway department, known as PennDOT, received reports of bones in what appeared to be an impromptu burial site beneath a broad meadow that had once been the site of a poorhouse, said Bob Rescorla, a PennDOT inspector at the site.

'There were rumors it was a mass grave here,' Rescorla said of the burial ground along State Highway 61 in Schuylkill Haven, about 100 miles northwest of Philadelphia. Historians say the Spanish flu pandemic touched all parts of the world and claimed tens of millions of lives. The flu could kill quickly, sometimes in less than a day.

In Schuylkill County, the Pottsville Republican-Herald newspaper reported that some 17,000 residents were sickened and several thousand died during the pandemic, leaving as many as 3,000 children orphaned.

In what is sure to cause controversy, a researcher has claimed that the mysterious and ancient ruts which crisscross the Phrygian Valley of Turkey were caused by an unknown and intelligent race between 12 and 14 million years ago.

Dr. Alexander Koltypin, geologist and a director of the Natural Science Scientific Research Centre at Moscow's International Independent University of Ecology and Politology has recently completed investigations at the site in Anatolia which is marked with strange ruts, described as "petrified tracking ruts in rocky tuffaceous deposits' made from compacted volcanic ash," according to MailOnline.

Prehistoric man may have been responsible for the first ever war crime, after German archaeologists found a mass grave with evidence that the victims had been tortured and slain.

Researchers at the University of Mainz have been studying the remains of 26 people who were found dumped in a bit dating from the early Neolithic, around 4000BC.

Although mass graves have been found before from the stone age, it is the first time that skeletons have shown evidence of needless violence.

Most of the skull bones revealed that the victims had been hit over the head with a blunt instrument, while arrow heads nearby suggest they could have been killed by bowmen.

But for the first time there was evidence of deliberate and systematic smashing of the lower leg bones of a number of individuals suggesting that the victims were either tortured before or mutilated after death.

The grave was discovered at Schöneck-Kilianstädten, Darmstadt, in 2006, and archaeologist have been excavating the site and studying the bones ever since.

Researchers have discovered unique inscriptions on the wall of a cave in China recording the effects of droughts on the local population over the course of 500 years.

The inscriptions were found on the walls of Dayu Cave in the Qinling Mountains of central China by a team of international experts including scientists from the University of Cambridge in the UK. When there was a drought, people from the local area would go to the cave to collect water and to pray for rain. Some of them recorded the impacts of the drought by writing a graffiti-type scrawl on the yellow rock wall. Seven such droughts occurring between 1520 and 1920 were recorded in this way. For example, one of the inscriptions, from 1891, reads:

"On May 24th, 17th year of the Emperor Guangxu period, Qing Dynasty, the local mayor, Huaizong Zhu led more than 200 people into the cave to get water. A fortune-teller named Zhenrong Ran prayed for rain during the ceremony."

Adding to the number of unsolved mysteries regarding the ancient origins of humanity and the biology of our species, scientists have discovered that we have less DNA now than our ancient ancestors possessed. Are we de-evolving?

A study published this week in the journal Science has found that modern humans lost DNA as we evolved after our split from apes. Our ancient ancestors, early humans, possessed substantially more amounts of genetic data than we do now. This surprising discovery raises many questions, the most obvious one being: why did we lose all that genetic information? Also, what difference has the loss made?

The short answer is: we don't know yet.

According to news website Gizmodo, the team of researchers led by Professor Evan Eichler, geneticist at the Department of Genome Sciences, University of Washington, sequenced the genomes of 236 individuals from 125 distinct populations. They found that Homo sapiens have shed approximately 40.7 million base pairs of DNA after breaking from our closest living relatives, chimpanzees, around 13 million years ago.

Washington — DNA testing all but confirmed Thomas Jefferson slept with his slave Sally Hemings. Now it's rewriting another lurid chapter in presidential history, this one from the Roaring '20s.

Genetic analysis has proved that President Warren G. Harding fathered a child with long-rumored mistress Nan Britton, according to AncestryDNA, a DNA-testing division of Ancestry.com.

Britton set off a Jazz Age sex scandal when she went public with her tale of forbidden love in the White House, boldly publishing her story in a 1927 best-selling memoir, The President's Daughter. But historians long questioned her claims, and Harding defenders vilified her as a liar for nearly 90 years.

Based on DNA from Britton's grandson and descendants of Harding, the results are 99.9 percent certain, Ancestry.com said. The findings were first reported Thursday by The New York Times.

The child born of their union, Elizabeth Ann Blaesing, was the only known offspring of the 29th president. She died in 2005. Britton died in 1991.

James Blaesing, 65, who grew up hearing the story of his grandfather, the president, from Britton, his grandmother, told The Associated Press he long wanted to prove she was telling the truth. He was delighted by the DNA results.

"You know what this is? It's a love story," he said of his grandparents. "It was true love, especially on her side, and I know he felt the same way. And he got trapped."

Harding was a heartthrob U.S. senator from Ohio when the affair began. The relationship continued when Harding was president, with Britton later writing of how they made love in a White House coat closet. It ended with Harding's sudden death during his presidency in 1923.

Harding's family long maintained that Britton's book was a lie or a childhood fantasy or was perhaps dreamed up by Democratic opponents of the Republican president. Some people maintained that Harding was sterile because he had mumps as a child.

The Library of Congress recently published love letters between Harding and another woman, Carrie F. Phillips, opening further doubts about the family's denials.