Oldest human genome reveals roots of first Americans – New Scientist
http://news.google.com Wed, 20 Nov 2013 18:02:22 GMT
Design & TrendOldest human genome reveals roots of first AmericansNew ScientistA 24,000-year-old boy from Siberia is helping redraw the Native American family tree. He is the oldest human to have his genome sequenced, and the results suggest that the …
A 24,000-year-old boy from Siberia is helping redraw the Native American family tree. He is the oldest human to have his genome sequenced, and the results suggest that the first people to colonise the Americas were not simply east Asians. Instead, those early settlers had both western Eurasian and east Asian roots.
The first Americans probably arrived from north-east Asia via a land bridge, around 15,000 years ago. Confusion arose because Native Americans have DNA that resembles that of people in east Asia, but no modern contemporary population exactly fits, says Eske Willerslev of the Natural History Museum of Denmark in Copenhagen.
Plus Native Americans carry some DNA characteristic of modern Europeans, which has led some researchers to suggest that America was first colonised from Europe, not Asia.
Read more …
Ancient humans interbred with Neanderthals, Denisovans and a mystery species that may have originated in Africa and migrated to Asia, paleontologists said this week.
Improved genome sequencing from two extinct human relatives suggests the forerunners to modern humans intermingled with one another more extensively than was previously known.
Ancient genomes, one from a Neanderthal and one from a different archaic human group, the Denisovans, were presented Monday at the Royal Society in London, where researchers said they’d found evidence to suggest rampant interbreeding among members of ancient human-like groups more than 30,000 years ago in Europe and Asia – including an unknown human ancestor.
“What it begins to suggest is that we’re looking at a ‘Lord of the Rings’-type world — that there were many hominid populations,” said Mark Thomas, evolutionary geneticist at University College London.
Previous Neanderthal and Denisovan genome sequences showed the two groups had interbred with anatomically modern humans, contributing to the genetic diversity of modern humans, and revolutionized the study of ancient human history.
But those genome sequences were of low quality and full of gaps and errors.
A team led by David Reich, an evolutionary geneticist at Harvard Medical School in Boston, Massachusetts, and Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, said they’d produced genome sequences that matched the quality of modern human genomes.
All humans whose ancestry originates outside Africa have about 2 percent Neanderthal genomes, and some Oceanic humans, such as Papua New Guineans and Australian Aboriginals, have about 4 percent of their DNA from interbreeding between their human ancestors and Denisovans, whose remains were found in a cave in Siberia’s Altai Mountains.
Researchers said the Denisovans interbred with Neanderthals and humans who lived in China, East Asia and Oceania.
Scientists have mapped the genome of a four-year-old boy who died in south-central Siberia 24,000 years ago.
The Mal’ta boy was buried with a variety of artifacts, including a Venus figurine
Scientists have mapped the genome of a four-year-old boy who died in south-central Siberia 24,000 years ago.
It is the oldest modern human genome sequenced to date, researchers report in the journal Nature.
The results provide a window into the origins of Native Americans, whose ancestors crossed from Siberia into the New World during the last Ice Age.
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They suggest about a third of Native American ancestry came from an ancient population related to Europeans.
Analysing the genes of present-day populations can only tell us so much about the past because traces of ancient movements have been overwritten many times.
So studying the DNA from ancient remains is becoming a powerful tool for disentangling the numerous waves of migration that produced the genetic patterns seen in people today.
The burial of an Upper Palaeolithic Siberian boy was discovered along with numerous artifacts in the 1920s by Russian archaeologists near the village of Mal’ta, along the Belaya river.
The DNA of ancient viruses first spotted in the Neanderthal genome have now been identified in modern humans – although whether they cause disease is not yet clear.
In 2010, researchers unveiled the genomes of two extinct groups of human – the Neanderthals and the Denisovans. This revealed that some humans share a few per cent of their DNA with their extinct cousins. Ever since, geneticists have been poring over the ancient DNA sequences for an insight into Stone Age life.
Last year, Jack Lenz’s team at the Albert Einstein College of Medicine in New York began looking for signs of endogenous retroviruses in the ancient genomes, a class of virus that not only invades cells but worms its way into DNA. These retroviral gene sequences make up about 8 per cent of the human genome, and are part of what is sometimes called “junk” or non-coding DNA because they don’t contain genetic instructions to make proteins.
Lenz found 14 retroviral gene sequences in the Neanderthal and Denisovan DNA. When he compared this to the human genome used as a standard reference, he found that none of the sequences overlapped – in other words, it seemed that modern humans did not share this endogenous retroviral DNA with their extinct cousins.
Not so fast
That was until Robert Belshaw at Plymouth University, UK, and Gkikas Magiorkinis at the University of Oxford, who study whether these viral DNA sequences contribute to disease, decided to take a closer look.
They examined the genomes of 67 people with cancer, and found they each contained seven of the sequences supposedly unique to the ancient humans. Belshaw suspects that all 14 might still be around, although finding the rest will take more time. The viruses insert themselves into DNA repeats – patterns that occur in multiple locations throughout the genome, only one of which will carry the sequence in question, so tracking them down is time consuming.
The finding suggests that the viruses probably infected our ancestors before we split from the lineage that led to Neanderthals and Denisovans, roughly 400,000 years ago.
So why did Lenz’s team miss the retroviral sequences in humans?
Stone-tipped spears predate existence of humans by 85,000 years
Remains of the world’s oldest known stone-tipped throwing spears, described in a new paper, and so ancient that they actually predate the earliest known fossils for our species by 85,000 years.
There are a few possible implications, and both are mind-blowing. The first is that our species could be much older than previously thought, which would forever change the existing human family tree.
The second, and more likely at this point, is that a predecessor species to ours was extremely crafty and clever, making sophisticated tools long before Homo sapiens emerged.
Homo heidelbergensis, aka Heidelberg Man, lived in Africa, Europe and western Asia from at least 600,000 years ago. He clearly got around, and many think this species was the direct ancestor ofHomo sapiens in Africa and Neanderthals in Europe and Asia
(Reuters) – Humans first made dogs their best friends in prehistoric Europe, where groups of hunter-gathers learnt to tame dangerous wolves into companions between 19,000 and 32,000 years ago, scientists said on Thursday.
The new research, based on analysis of DNA fragments from fossils of ancient wolves and dogs, confounds earlier theories that dogs were originally domesticated in the Middle East or East Asia.
Experts generally agree that dog training started out with a few grey wolves hanging around human encampments in the hope of picking up scraps. Over time, humans accepted them, perhaps initially as guards or hunting partners, and taught them to be useful companions.
Where and when this happened, however, has been a matter of controversy.
Now Olaf Thalmann, from Finland’s University of Turku, and colleagues believe they have placed initial doggy taming firmly in Europe after finding that modern dogs’ DNA most closely matches that of either ancient European canines or modern European wolves, but not wolves outside Europe.
“We’re pretty sure that Europe played a major role in the domestication of the dog,” Thalmann, whose research was published on Thursday in the journal Science, said in an interview.
Ancient DNA helps researchers unlock secrets of a cave bear and horse which roamed Earth hundreds of thousands of years ago.
SANTA FE—Where did the first Americans come from? Most researchers agree that Paleoamericans moved across the Bering Land Bridge from Asia sometime before 15,000 years ago, suggesting roots in East Asia. But just where the source populations arose has long been a mystery.
Now comes a surprising twist, from the complete nuclear genome of a Siberian boy who died 24,000 years ago—the oldest complete genome of a modern human sequenced to date. His DNA shows close ties to those of today’s Native Americans. Yet he apparently descended not from East Asians, but from people who had lived in Europe or western Asia. The finding suggests that about a third of the ancestry of today’s Native Americans can be traced to “western Eurasia,” with the other two-thirds coming from eastern Asia, according to a talk at a meeting* here by ancient DNA expert Eske Willerslev of the University of Copenhagen. It also implies that traces of European ancestry previously detected in modern Native Americans do not come solely from mixing with European colonists, as most scientists had assumed, but have much deeper roots.
I’m still processing that Native Americans are one-third European,” says geneticist Connie Mulligan of the University of Florida in Gainesville. “It’s jaw-dropping.” At the very least, says geneticist Dennis O’Rourke of the University of Utah in Salt Lake City, “this is going to stimulate a lot of discussion.” Researchers have been trying to parse the origins of the first Americans for decades. Most agree that people moved across Beringia, via a vast ice age land bridge (see map p. 410), and began spreading through the Americas, reaching Chile by 14,500 years ago. But the origins of the source populations are not clear, and some archaeologists have even suggested that ancient Europeans crossing the Atlantic were part of the mix (Science, 16 March 2012, p. 1289). Others have contended that early skeletons found in the Americas, such as the 9000-year-old Kennewick Man, show some European features (Science, 10 April 1998, p. 190). In his talk, Willerslev argued that the ancient genome “can actually explain a lot of these inconsistencies,” by offering glimpses of prehistoric populations before more recent migrations and other demograp
Oct. 17, 2013 at 2:33 PM ET
Georgian National Museum
An oddball skull from a site in the former Soviet republic of Georgia has sparked a debate over early human evolution.
Putting together the pieces of a 1.8 million-year-old skull from the former Soviet republic of Georgia has led researchers to a surprising conclusion: Specimens that supposedly represent several early human species might be merely different-sized individuals from the same species.
If the conclusion holds up, the skull discovery would require a major rewrite for the story of early human evolution. Such species as Homo habilis and Homo rudolfensis, long a part of humanity’s “bushy” family tree, could be folded into a wide-ranging species known as Homo erectus.
“It is really an extraordinary find in many respects,” Christoph Zollikofer of Zurich’s Anthropological Institute and Museum, one of the researchers behind the study published in this week’s issue of the journal Science, told reporters during a teleconference.
The key to the claim is the assembly of a fossil called Skull 5. The specimen was discovered in separate pieces at a sprawling excavation in Dmanisi, about 50 miles (80 kilometers) from Tbilisi, Georgia’s capital. Over the past eight years, Skull 5’s jaw and the cranium were painstakingly matched up and compared with four other hominid skulls unearthed at the site.
C. Zollikofer and M. S. Ponce de Leon / Univ. of Zurich
This graphic shows the five skulls found at the Dmanisi dig, numbered 1 through 5.
Professor Bryan Sykes: “Yeti hairs genetically identical to polar bear”
Research by a British scientist has concluded that the legendary Himalayan yeti may in fact be a sub-species of brown bear.
DNA tests on hair samples carried out by Oxford University genetics professor Bryan Sykes found that they matched those from an ancient polar bear.
He subjected the hairs to the most advanced tests available.
He says the most likely explanation for the myth is that the animal is a hybrid of polar bears and brown bears.
Prof Sykes told the BBC that there may be a real biological animal behind the yeti myth.
“I think this bear, which nobody has seen alive,… may still be there and may have quite a lot of polar bear in it,” he said.
“It may be some sort of hybrid and if its behaviour is different from normal bears, which is what eyewitnesses report, then I think that may well be the source of the mystery and the source of the legend.