Human Genome News -  page 18
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DNA analysis points to humanity's oldest civilization - 9/23/16
-- New DNA Analysis Technique Aids in Study of Early Human Migrations - 1/22/13
Our Tangled Ancestry - 2/10/14
-- Computer Model Simulates Ancient Climate Change, Migration - 9/22/16


 DNA analysis points to humanity's oldest civilization

Published September 23, 2016

New research suggests that the title of world's oldest civilization goes to the indigenous populations of Australia and Papua New Guinea. Scientists say the DNA of these people can be traced back to an original wave of settlers from Africa more than 50,000 years ago, reports the Guardian.

“They are probably the oldest group in the world that you can link to one particular place,” says the University of Copenhagen's Eske Willerslev, lead author of a new study in Nature.

It finds that the ancestors of these indigenous populations arrived on Sahul—a supercontinent that once included New Guinea, Australia, and Tasmania, per the Telegraph—between 51,000 and 72,000 years ago.

In fact, the study suggests they were the first people to cross an ocean. "Now we know their relatives are the guys who were the first real human explorers," says Willerslev.

"Our ancestors were sitting being kind of scared of the world while they set out on this exceptional journey across Asia and across the sea.” At some point, they seem to have interbred with an unspecified early human relative whose DNA has left a small mark on their modern genetic makeup—it accounts for about 4% of it. The study, based on analysis of 83 indigenous Australians and 25 Papuans, found that the group remained largely isolated until about 4,000 years ago, when they encountered populations from Asia and then Europe. (A related study found that almost everyone is descended from a single wave of African migrants.)

This article originally appeared on Newser: Scientists Find Earth's Oldest Civilization

 New DNA Analysis Technique Aids in Study of Early Human Migrations

January 22, 2013

LEIPZIG, GERMANY—A new technique that identifies ancient human DNA even when large amounts of DNA from soil bacteria are also present has been used to study a 40,000-year-old modern-human leg bone. The findings suggest that the remains, which were found in China’s Tianyuan Cave in 2003, came from an ancestor of present-day Asians and Native Americans. The DNA tests also indicate that this ancestor had already split from the ancestors of present-day Europeans. “More analyses of additional early modern humans across Eurasia will further define our understanding of when and how modern humans spread across Europe and Asia,” said Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology.

 Computer Model Simulates Ancient Climate Change, Migration

Tobias Friedrich    September 22, 2016

Milankovitch cycles simulation

MANOA, HAWAII—Live Science reports that scientists led by Axel Timmermann of the University of Hawaii at Manoa have developed a new computer simulation, spanning a period of 125,000 years, of how rainfall, temperature, sea levels, glacial ice, vegetation, carbon dioxide levels, and the migration patterns of modern humans might have been affected by Milankovitch cycles, or wobbles in the planet’s orbit and tilt that occur every 21,000 years. The model suggests that modern humans may have traveled between northeastern Africa and other parts of the world through periodic “habitable green corridors” in the Sahara and Arabian deserts. Timmermann says these results align with archaeological and fossil data from the Middle East, Europe, Asia, Australia, and the Americas. “If the climate had been constant over the past 125,000 years, we would have evolved in a very different way,” he said. A future version of the simulation will add Neanderthals, interbreeding, cultural exchange, and competition for food into the mix. For more on modern human origins, go to "Our Tangled Ancestry."

 Our Tangled Ancestry

By ZACH ZORICH    February 10, 2014

When scientists attempt to draw the evolutionary family tree of the human race, they would like to be able to use straight lines to show the relationships between hominin groups: one species leads to another, and so on. But this isn’t always possible. Three recent studies of ancient DNA have uncovered unique genetic markers in unexpected places, showing that our ancestors got around and interbred more than anyone had previously thought. The result is a convoluted set of relationships among early humans where once there was a simpler family tree.

The story of this new work begins in northern Spain. There, a group of Spanish researchers at the site of Sima de los Huesos teamed up with geneticists from the Max Planck Institute for Evolutionary Anthropology to examine the oldest known hominin DNA sample, which comes from a 400,000-year-old Homo heidelbergensis thigh bone. They sequenced the bone’s mitochondrial DNA (mtDNA), which is passed from mother to child. “What we were expecting to see was Neanderthal mitochondrial DNA,” says Matthias Meyer of the Max Planck Institute, as Neanderthals would later occupy that part of Europe and might be expected to carry genetic material from the previous inhabitants. Surprisingly, the mtDNA is instead more closely related to that of a hominin who lived more than 50,000 years ago in Siberia’s Denisova Cave than it is to that of Neanderthals. The Denisovans were related to, but genetically distinct from, Neanderthals.

According to Meyer, the Sima de los Huesos sample is old enough that it could represent an ancestor to both Denisovans and Neanderthals. However, it is also possible that H. heidelbergensis is not ancestral to either group, but later interbred with the Denisovan lineage. Studies of nuclear DNA, which contains genetic information from both parents, will be needed to clarify the relationship, Meyer believes.

Max Planck Institute scientists also recently sequenced the genome of a second individual who lived at Denisova more than 50,000 years ago. They discovered that the individual was actually a Neanderthal, not a Denisovan. It is the most complete Neanderthal genome yet recovered, and it has given geneticists a novel point of comparison among various human lineages. The new analysis shows that occasional interbreeding between Neanderthals, Denisovans, and Homo sapiens probably took place in more than one time and place, and that the Denisovans also interbred with an unknown archaic hominin group—possibly H. heidelbergensis.

Denisova Cave, Siberia    According to another new study with surprising results, a small percentage of the Denisovans’ unique DNA still lives on in the indigenous people of Australia, New Guinea, and the eastern islands of Indonesia—all places that are separated from the Asian mainland by strong ocean currents that form a migratory barrier called the Wallace Line. Based on the lack of Denisovan DNA markers in ancient and modern populations on the Asian side of the line, and their relative abundance on the other, Alan Cooper of the University of Adelaide and Christopher Stringer of London’s Natural History Museum believe that Denisovans may have boated to locations across the Wallace Line and interbred with the H. sapiens already living there.

While these studies paint a complex picture of our genetic past, Meyer believes the relationships between ancient humans will become clear as methods for recovering ancient DNA improve. “In the next year or two,” he says, “we will have a much, much higher-resolution picture of human migrations out of Africa and within Eurasia.”






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