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10# cpan0256

原文网址:The genomic landscape of Neanderthal ancestry in present-day humans --- Nature : Nature Publishing Group
imvivi001 发表于 2014-6-14 20:57

Comprehensive candidate gene study highlights UGT1A and BNC2 as new genes determining continuous skin color variation in Europeans.
Jacobs LC1, Wollstein A, Lao O, Hofman A, Klaver CC, Uitterlinden AG, Nijsten T, Kayser M, Liu F.
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Natural variation in human skin pigmentation is primarily due to genetic causes rooted in recent evolutionary history. Genetic variants associated with human skin pigmentation confer risk of skin cancer and may provide useful information in forensic investigations. Almost all previous gene-mapping studies of human skin pigmentation were based on categorical skin color information known to oversimplify the continuous nature of human skin coloration. We digitally quantified skin color into hue and saturation dimensions for 5,860 Dutch Europeans based on high-resolution skin photographs. We then tested an extensive list of 14,185 single nucleotide polymorphisms in 281 candidate genes potentially involved in human skin pigmentation for association with quantitative skin color phenotypes. Confirmatory association was revealed for several known skin color genes including HERC2, MC1R, IRF4, TYR, OCA2, and ASIP. We identified two new skin color genes: genetic variants in UGT1A were significantly associated with hue and variants in BNC2 were significantly associated with saturation. Overall, digital quantification of human skin color allowed detecting new skin color genes. The variants identified in this study may also contribute to the risk of skin cancer. Our findings are also important for predicting skin color in forensic investigations.

Comprehensive candidate gene study highlights UGT1A and BNC2 as new genes determining continuous skin color variation in Europeans. - PubMed - NCBI  https://www.ncbi.nlm.nih.gov/pubmed/23052946
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23# Hanhe
本帖最后由 Hanhe 于 2017-3-30 20:08 编辑

奋斗 发表于 2014-6-14 18:11
Skull discovery suggests location where humans first had sex with Neanderthals | Science | The Guardian

Skull found in northern Israeli cave in western Galilee, thought to be female and 55,000 years old, connects interbreeding and move from Africa to Europe

Views of the human skull, with missing jaw, found in western Galilee, northern Isreal and estimated at 55,000 years old. Photograph: Tel Aviv University and University of Vienna

Ian Sample, science editor

Wednesday 28 January 2015 18.18 GMTFirst published on Wednesday 28 January 201517.59 GMT

An ancient skull found in a cave in northern Israel has cast light on the migration of modern humans out of Africa and the dawn of humanity’s colonisation of the world.
For most palaeontologists that might be enough for a single fossil, but the braincase has offered much more: a likely location where the first prehistoric trysts resulted in modern humans having sex with their heavy-browed Neanderthal cousins.
Discovered in a cave in western Galilee, the partial skull belonged to an individual, probably a woman, who lived and died in the region about 55,000 years ago, placing modern humans there and then for the first time ever.
Homo sapiens walked out of Africa at least 60,000 years ago, but the harsh climate in parts of Europe at the time hampered their spread across much of the continent until about 45,000 years ago.
The skull reveals that modern humans reached the Levant where the population may have given rise to those who later colonised Europe when the frozen climate abated and the territory became more habitable.
Israel Hershkovitz at Tel Aviv University said the skull, though missing its face and jaws, was an extraordinary find. Distinctly modern in its anatomy, the braincase resembles the European Cro-Magnons (robustly built early modern humans), but retains some African features too. “It’s amazing. This is the first specimen we have that connects Africa to Europe,” Hershkovitz told the Guardian.

The excavation area of where the skull was found in western Galilee in a cave that had collapsed around 30,000 years ago. Photograph: Israel Hershkovitz, Ofer Marder & Omry BarzilaiPalaeontologists spotted the skull on a rocky shelf in the side chamber of the enormous Manot cave that was discovered by chance when a bulldozer broke through the roof while cutting a sewer trench for a nearby village.

When scientists abseiled through the hole torn in the ceiling, they found the cave opened up more than 20 metres deep, 50 metres wide and 100 metres long. The original entrance to the cave had collapsed about 30,000 years ago, sealing off the contents.
“We couldn’t believe our eyes. We immediately realised it was a prehistoric cave and that it had been inhabited for a very long time. Because the entrance had collapsed so long ago, it had been frozen in time. Nobody had been inside for 30,000 years,” said Hershkovitz.
“There is a huge central cave and several beautiful side chambers. In one side chamber, the skull was lying there on top of a rocky shelf. It was there waiting for us. We just had to pick it up,” he added.
Excavations at the site have yielded an impressive haul of modern human and antelope bones, but the partial skull is the oldest of the human remains recovered from the cave. How it came to be perched on a shelf in a side chamber of the cave is a mystery: it may have come to rest there after being washed in by floodwater. Or perhaps it was placed there intentionally by another individual living in the cave.

Location of Manot Cave in Israel

Writing in the journal Nature, the scientists explain how dating the skull to 55,000 years ago reveals that modern humans arrived in the region when it was already well populated with Neanderthals. Skeletons of Neanderthals from the same time have been recovered from Amud cave 24 miles (40km) to the east of Manot cave, and from Kebara cave 30 miles to the south.

That modern humans and Neanderthals shared the land around Manot cave 50,000 to 60,000 years ago means that the rolling hills of what is now Galilee may have provided the romantic backdrop to the spell of interbreeding that left non-Africans with a smidgen of Neanderthal DNA. Genetic studies suggest that humans and Neanderthals mixed in the same 50,000 to 60,000-year-old period, most probably in western Asia.

“Manot is the best candidate for the interbreeding of modern humans with Neanderthals and there is really no other candidate,” Hershkovitz said. “The people at Manot cave are the only population we know of that shared the same geographical region for a very long period of time,” he added. Without DNA from the skull, it is impossible to know if the Manot cave individual was a product of such couplings.

Chris Stringer, head of human origins at the Natural History Museum, said the region was certainly a contender for the main interbreeding that happened 50 millennia ago, though further north than modern day Israel was possible.

“At about 55,000 years old, this is the first modern human from western Asia which is well dated to the estimated timeframe of interbreeding between early modern humans and Neanderthals,” he said.

“Manot might represent some of the elusive first migrants in the hypothesised out-of-Africa event about 60,000 years ago, a population whose descendants ultimately spread right across Asia, and also into Europe. Its discovery raises hopes of more complete specimens from this critical region and time period,” he added.

  https://www.theguardian.com/scie ... on-sex-neanderthals
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