-- Lost Colony of Roanoke - 1/1/12
-- Discovery of Oldest DNA Scrambles Human Origins - 12/04/13
Lost Colony of Roanoke
Genotyping could answer a centuries-old mystery about a vanished group of British settlers.
By Kerry Grens | January 1, 2012
Lost Colony Research Group volunteers, grad students, and Outer Banks locals at an archaeological dig site on Hatteras Island.
Roberta EstesThe legend of the Lost Colony of Roanoke has haunted American history for centuries. In July 1587, a British colonist named John White accompanied 117 people to settle a small island sheltered within the barrier islands of what would become North Carolina’s Outer Banks. When conditions proved harsher than anticipated, White agreed to sail back to Britain to shore up the settlement’s supplies—a trip that should have lasted a few months.
When White belatedly returned in 1590, the colonists had vanished—more than 100 men, women, and young children, their shelters and belongings, all gone. According to White’s writings, the only trace they left behind was a structure of tree trunks, with a single word carved into one post: CROATOAN.
The creepiness of the Lost Colonists’ disappearance didn’t discourage future American settlement. Nor has the lack of clues about their fate discouraged professional and amateur historians from trying to figure out what happened to them.
Archaeological digs, weather records, historical writings, genealogy—none have fully answered the question of what happened during White’s absence. But Roberta Estes, who owns DNAeXplain, a company that interprets the results of genetic heritage tests, is looking to DNA for help. Her hypothesis is that the Lost Colonists survived, and that evidence of their salvation is tucked away in the mitochondrial or Y chromosomal DNA of living descendents.
“They were stranded,” Estes says of the settlers. “They knew they couldn’t survive there on the island.” The colonists’ solution, in her estimation, was to go native.
“Croatoan,” Estes explains, was a message to White indicating that the colonists had gone to live with the Croatan Indians who lived on nearby Hatteras Island. Estes’s volunteer organization, the Lost Colony Research Group, is recruiting people from the area to submit DNA samples and family histories to test her theory.
Studying patterns of short tandem repeats (STRs) on the Y chromosomes of living men can determine whether they are likely to share a common ancestor that was a member of the Lost Colony. For example, Estes can compare the STR profile of a man whose family history suggests that his ancestors lived on Hatteras Island in the 17th century against genetic databases to see if he’s related to anyone with a Lost Colonist surname, such as Dare, Hewet, or Rufoote.
Additionally, it’s possible to scan that man’s mitochondrial or Y chromosomal DNA for evidence of Native American heritage, creating a clearer picture of what became of the vanished colonists. “It is true that with Y chromosome and mitochondrial DNA you can assign them unequivocally to different ethnic groups,” says Ugo Perego, a senior researcher at the Sorenson Molecular Genealogy Foundation. But, he adds, it would be difficult to tell exactly when the European ancestry was introduced.
Estes has amassed early land-grant records detailing who lived in the Outer Banks area a few centuries ago. Some of the putative Native Americans living there are thought to have adopted the last names of their European neighbors, she says. If Estes can show that the descendents of these Native American families have DNA matching families with Lost Colony surnames, that would suggest that the colonists mixed with the Croatan Indians.
“It’s a romantic idea,” says Charles Ewen, an East Carolina University anthropology professor who is writing a book about the Lost Colony. Ewen, who’s also working with Estes on an archaeological dig in the Outer Banks, offers other possibilities for the Colony’s fate that are far less rosy. The settlers battled a severe drought while White was journeying back to England that could have made trying conditions worse; Native Americans or Spanish arrivals could have killed the settlers; or the colonists could have tried to sail back to Britain in White’s wake and perished.
Ewen says there are some historical examples of settlers assimilating into native groups, but none in which an entire colony was adopted. “I won’t rule it out, but the whole group forming new tribal identities? I don’t buy it.”
Estes’s group is commencing a new archaeological dig this year to look for Lost Colony artifacts. Previous digs on Hatteras Island have yielded British and Native American items in the same stratum of soil, thought to predate English homesteads from the 1700s, indicating that the groups commingled, she says.
Ewen says he hopes the dig can also help answer questions about the vanished Native Americans who once lived on the Outer Banks. “We don’t know what happened to them.” Like that of the Lost Colonists, the fate of the Croatan Indians is also buried in history.
Reprinted by permission from http://the-scientist.com/2012/01/01/lost-colony-dna/
of Oldest DNA Scrambles Human Origins
The bones were first thought to belong to European Neanderthals, but analysis showed they are genetically closer to the Siberian Denisovans.
December 4, 2013 By Karl Gruber for National Geographic
New tests on human bones hidden in a Spanish cave for some 400,000 years set a new record for the oldest human DNA sequence ever decoded—and may scramble the scientific picture of our early relatives.
Analysis of the bones challenges conventional thinking about the geographical spread of our ancient cousins, the early human species called Neanderthals and Denisovans. Until now, these sister families of early humans were thought to have resided in prehistoric Europe and Siberia, respectively. (See also: "The New Age of Exploration.")
But paleontologists write in a new study that the bones of what they thought were European Neanderthals appear genetically closer to the Siberian Denisovans, as shown by maternally inherited "mitochondrial" DNA found in a fossil thighbone uncovered at Spain's Sima de los Huesos cave.
"The fact that they show a mitochondrial genome sequence similar to that of Denisovans is irritating," says Matthias Meyer of Germany's Max Planck Institute for Evolutionary Anthropology in Leipzig, lead author of the study, published Wednesday in Nature.
"Our results suggest that the evolutionary history of Neanderthals and Denisovans may be very complicated and possibly involved mixing between different archaic human groups," he said.
Neanderthals and Denisovans arose hundreds of thousands of years before modern-looking humans spread worldwide from Africa more than 60,000 years ago. The small traces of their genes now found in modern humans are signs of interbreeding among ancient human groups.
Previously, the oldest human DNA sequenced came from bones that were less than 120,000 years old.
Meyer said stable temperatures in the cave helped preserve the mitochondrial DNA, and credited recent advances in gene-sequencing technology for establishing the basis for the new milestone.
Mixed Up or Mixing It Up?
For humanity's tangled past, the new mitochondrial DNA results raise an unexpected question: How does a Spanish early human species end up with Siberian DNA?
The authors propose several possible scenarios. For instance, Sima hominins could simply be close relatives of the Denisovans. But that would mean they lived right alongside Neanderthals without having close genetic ties to them.
The Sima hominins could also be a completely independent group that mingled with Denisovans, passing on their mitochondrial DNA, but it would be hard to explain why they also have Neanderthal features.
Another possibility, suggested by anthropologist Chris Stringer of the Natural History Museum in London, is that mitochondrial DNA from the Sima people reached the Denisovans thanks to interspecies sexual adventures among early humans, which introduced the DNA to both the Sima and Denisovans.
In the end, the identity of these ancient people remains a mystery, and further work is needed to clarify their identity. "The current genetic data [mitochondrial DNA] is too limited to conclude much about their population history," Meyer says.
As with the Denisovans, only the decoding of the full genetic map or genome, and not just the mitochondrial DNA, will provide convincing evidence of Sima family history, Meyer says.
New Piece of the Puzzle
In recent years, paleogeneticists have released surprising reports about such early human species, notably the interspecies breeding that likely occurred among Neanderthals, Denisovans, and modern humans.
Uncovered only in 2010, Denisovans are known solely from a pinkie and a tooth found in 30,000- to 50,000-year-old rock layers in Siberia's Denisova cave. DNA from those Siberian bones first established their owners as genetically distinct from Neanderthals and modern people.
(Read "The Case of the Missing Ancestor" in National Geographic magazine.)
"The fact that the Sima de los Huesos [mitochondrial DNA] shares a common ancestor with Denisovan rather than Neanderthal [mitochondrial DNA] is unexpected in light of the fact that the Sima de los Huesos fossils carry Neanderthal-derived features," says the study.
But paleoanthropologist John Hawks of the University of Wisconsin, Madison, who was not part of the study, says "there's not really anything very surprising" about the Spanish bones' bearing mitochondrial DNA that is not an earlier version of Neanderthal genes.
Ancient mitochondrial DNA from many other species—"bison, mammoths, cave bears, and others"—doesn't resemble that of more recent species, he notes.
Hawks is more cautious than the study authors about regarding the Spanish genes and younger Denisovan ones as being closely related: "The difference between Sima and Denisova [gene] sequences is about as large as the difference between Neanderthal and living human sequences.
"It would not be fair to say that Denisova and Sima represent a single population, any more than that Neandertals and living people do."
One reason for caution is that mitochondrial DNA results in the past have pointed scholars in errant directions; for example, some early studies suggested that humans and Neanderthals did not share any common ancestry.
Mitochondrial DNA is a small part of the human genome that is generally transmitted only through the female line, from mothers to offspring. This has important implications for the study of past events.
For instance, ancient interspecies breeding events might not be picked up by mitochondrial DNA.
But mitochondrial DNA can be transferred between species when interspecies mingling events occur. Such scenarios have been observed for other groups, such as polar and brown bears, where it has been found that interspecies breeding led to mixed-up mitochondrial genomes.
The Mountain of Bones
The Atapuerca Mountains, where the human bones were found, is a world-famous archaeological site located in northern Spain; a group of caves there contain some of Western Europe's oldest known human remains.
The most famous of these caves, Sima de los Huesos, has been studied since 1997 and hosts more than 6,000 ancient bone samples belonging to 28 ancient humans that lived roughly 400,000 years ago. The exact origin of the bone pile is unclear.
"Could a natural catastrophe or carnivore activities explain the accumulation of so many bodies?" asks anthropologist Juan-Luis Arsuaga, a co-author of the study and lead excavator at the cave for the past 30 years. "Or were there hominins that accumulated the corpses of their relatives and friends in such a dark and remote place: a pit in a cave?
"I would like to live to know the answer."
The bones of the Sima people share the features of Neanderthals, notably their thick-browed skulls, as well as the features of a much older group of human ancestors called Homo heidelbergensis, which lived about 600,000 years ago.
That species is also considered an ancestor of modern humans, Denisovans, and Neanderthals.
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