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Descent of Man In this lecture, beginners can familiarize themselves with basic information and terms used to describe the evolution of humanity beginning with the origin of primates through the comings and goings of Genus Homo. |
Scientists find gene that affects skin color
Posted: Friday, December 16, 2005
The merest fragment of one gene plays a major role in the differing skin colors of white and black people, scientists have found, capping an 11-year effort that began with the study of similar color variations in a common pet-store critter, the zebrafish.
The team of 25 geneticists, molecular biologists and anthropologists, most of them from Pennsylvania State University, says the work could have implications for skin cancer treatment, crime-scene analysis, and even cosmetics.
For those bent on altering their skin color, the gene could lead to pharmaceutical products that would be safer than tanning salons or the chemical skin-lightening creams popular in India, said project coordinator Keith C. Cheng, a cancer geneticist at the Penn State College of Medicine in Hershey, Pa.
The research, published today in the journal Science, also challenges a common assumption about when the various races branched off after leaving the scene of their common beginnings in Africa, more than 50,000 years ago. The people who would become Asians and northern Europeans were thought by some to have evolved their light skin together, before migrating their separate ways.
The new research indicates that the two groups developed lighter skin after the separation - giving just a taste of the secrets of history that can be unlocked with the human genome, said Penn State anthropologist Mark Shriver.
Full Article : gazettetimes.com
Fish helps solve puzzle of skin colour
'Golden gene' found in zebra fish same one that whitened skin of early Europeans
Genetic studies have humbled humans more than once. They've told us that we are 98-per-cent chimpanzee, that we share a great deal of our DNA with dogs and that even the fruit fly is a distant cousin.
Now, new research finds that humans and a common aquarium fish also have something in common. U.S. and Canadian scientists have discovered that a gene that lightens the scales of the zebra fish to a golden colour is the same one that helped to whiten the skin of the first Europeans.
A mutated form of this "golden gene," which most people of European descent carry, essentially suppresses the production of melanin, the pigment that gives skin its colour. Africans, East Asians and indigenous Americans carry an original form of the gene that contributes to their darker complexions.
Full Article : theglobeandmail.com
Scientists Find A DNA Change That Accounts for White Skin
Scientists said yesterday that they have discovered a tiny genetic mutation that largely explains the first appearance of white skin in humans tens of thousands of years ago, a finding that helps solve one of biology's most enduring mysteries and illuminates one of humanity's greatest sources of strife.
The work suggests that the skin-whitening mutation occurred by chance in a single individual after the first human exodus from Africa, when all people were brown-skinned. That person's offspring apparently thrived as humans moved northward into what is now Europe, helping to give rise to the lightest of the world's races.
Leaders of the study, at Penn State University, warned against interpreting the finding as a discovery of "the race gene." Race is a vaguely defined biological, social and political concept, they noted, and skin color is only part of what race is -- and is not.
In fact, several scientists said, the new work shows just how small a biological difference is reflected by skin color. The newly found mutation involves a change of just one letter of DNA code out of the 3.1 billion letters in the human genome -- the complete instructions for making a human being.
"It's a major finding in a very sensitive area," said Stephen Oppenheimer, an expert in anthropological genetics at Oxford University, who was not involved in the work. "Almost all the differences used to differentiate populations from around the world really are skin deep."
Full Article : washingtonpost.com
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Posted: Thursday, December 15, 2005
Source: www.eurekalert.org
Scientists at the University of York used a 'protein time capsule' to confirm the earliest record of human activity in Northern Europe.
A team of bio-archaeologists from York were able to provide the final piece of scientific evidence which confirmed that primitive stone tools discovered in East Anglia dated back around 700,000 years – 200,000 years earlier than any other traces of human colonisation of northern latitudes.
Dr Kirsty Penkman and Dr Matthew Collins were part of an international team, headed by the Ancient Human Occupation of Britain (AHOB) project, which studied the worked flint flakes discovered two years ago in a cliff at Pakefield near Lowestoft, Suffolk.
After members of the international team used stratigraphy to indicate the likely age of the flints, the York scientists were called in to confirm the antiquity of the artefacts using a newly-refined technique of amino acid analysis. The technique measures the extent of deterioration of proteins in fossils found close to the flints - in this case, opercula, the tiny trap-doors that close a snail's shell.
The results of the research are published in the latest edition of Nature today (Thursday 15 December 2005).
Dr Penkman, an Associate member of AHOB, said: "The amino acids were very securely contained in enclosed crystals of the opercula, unchanged by environmental factors other than normal internal protein degradation. In effect, they are a protein time capsule, enabling us to confirm the Pakefield opercula were significantly older than 500,000 years, the previous earliest date for humans north of the Alps."
Dr Collins said: "The method relies upon measuring the products of decomposition, so we had to isolate a protein sample that was well protected and did not leak the products of decay."
Dr Penkman added: "Helping to demonstrate the antiquity of the Pakefield site has been very exciting, and we are now trying to apply the same technique to more sites in Britain and overseas. A systematic survey will enable us to build a framework which records the extent of protein degradation in different sites, so that we can link the patchy terrestrial records of past climate change with the long continuous records from ice cores and marine sediments".
Notes for editors:
Up to now the oldest evidence of people north of the Alps was from about 500,000 years ago, though evidence of earlier human habitation has been discovered at sites in Italy and Spain.
BioArch is a joint venture between the Departments of Archaeology , Biology, and Chemistry. The labs are based in the Biology department, with analytical work conducted using facilities housed in the state of the art Technology Facility which shares three floors of the department's new £21.6M building.
The concept behind BioArch is to provide archaeologists with access to high quality analytical facilities. The BioArch building houses its own laboratories for research and teaching. These include a large 'clean' research laboratory, a soils/sectioning laboratory (also used for teaching), an HPLC laboratory (dedicated to amino acid analysis), an image analysis laboratory, a bone preparation laboratory, a balance room and a mass-spectrometry laboratory.
The Leverhulme Trust awarded a grant of more than £1 million for a five-year study of the Ancient Human Occupation of Britain (AHOB). Specialists from several Institutes and Universities are working together to investigate when people first arrived in Britain, and what factors led to their survival or local extinction. The work at York was funded by grants from English Heritage and the Natural Environment Research Council.
Kirsty Penkman has recently been awarded a Wellcome BioArchaeology fellowship to further develop and refine this dating technique.
'The earliest record of human activity in Northern Europe' is published in Nature http://www.nature.com/index.html
Reprinted from:
www.eurekalert.org/pub_releases/2005-12/uoy-bpo121505.php
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Humans in England May Go Back 700,000 Years Posted: Wednesday, December 14, 2005
Ancient tools found in Britain show that humans lived in northern Europe 200,000 years earlier than previously thought, at a time when the climate was warm enough for lions, elephants and saber tooth tigers to also roam what is now England.
Full Article : livescience.com
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Ancient humans brought bottle gourds to the Americas from Asia Posted: Wednesday, December 14, 2005
Source: www.eurekalert.org
Plants widely used as containers arrived, already domesticated, some 10,000 years ago
CAMBRIDGE, Mass., Dec. 13, 2005 -- Thick-skinned bottle gourds widely used as containers by prehistoric peoples were likely brought to the Americas some 10,000 years ago by individuals who arrived from Asia, according to a new genetic comparison of modern bottle gourds with gourds found at archaeological sites in the Western Hemisphere. The finding solves a longstanding archaeological enigma by explaining how a domesticated variant of a species native to Africa ended up millennia ago in places as far removed as modern-day Florida, Kentucky, Mexico and Peru.
The work, by a team of anthropologists and biologists from Harvard University, the Smithsonian Institution's National Museum of Natural History, Massey University in New Zealand and the University of Maine, appears this week on the web site of the Proceedings of the National Academy of Sciences.
Integrating genetics and archaeology, the researchers assembled a collection of ancient remnants of bottle gourds from across the Americas. They then identified key genetic markers from the DNA of both the ancient gourds and their modern counterparts in Asia and Africa before comparing the plants' genetic make-up to determine the origins of the New World gourds.
"For 150 years, the dominant theory has been that bottle gourds, which are quite buoyant and have no known wild progenitors in the Americas, floated across the Atlantic Ocean from Africa and were picked up and used as containers by people here," says Noreen Tuross, the Landon T. Clay Professor of Scientific Archaeology in Harvard's Faculty of Arts and Sciences. "Much to our surprise, we found that in every case the gourds found in the Americas were a genetic match with modern gourds found in Asia, not Africa. This suggests quite strongly that the gourds that were used as containers in the Americas for thousands of years before the advent of pottery were brought over from Asia."
The researchers say it's possible the domesticated gourds -- differentiated from wild bottle gourds by a much thicker rind -- were conveyed to North America by people who arrived from Asia in boats or who walked across an ancient land bridge between the continents, or that the gourds floated across the Bering Strait after being transported by humans from their native Africa to far northeastern Asia.
"This finding paints a new picture of the founding of the Americas," says co-author Bruce Smith of the Smithsonian Institution. "These people did not arrive here empty-handed; they brought a domesticated plant and dogs with them. They arrived with important tools necessary to survive and thrive on a new continent, including some knowledge of and experience with plant domestication."
Thought to have originated in Africa, bottle gourds (Lagenaria sicereria) have been grown worldwide for thousands of years. The gourds have little food value but their strong, hard-shelled fruits were long prized as containers, musical instruments and fishing floats. This lightweight "container crop" would have been particularly useful to human societies before the advent of pottery and settled village life, and was apparently domesticated thousands of years before any plant was domesticated for food purposes.
Radiocarbon dating indicates that bottle gourds were present in the Americas by 10,000 years ago and widespread by 8,000 years ago. Some of the specimens studied by the team were not only the oldest bottle gourds ever found but also quite possibly the oldest plant DNA ever analyzed. The newest of their archaeological samples, a specimen found in Kentucky, was just 1,000 years old -- suggesting the gourds were used in the New World as containers for at least 9,000 years.
Tuross and Smith's co-authors on the PNAS paper are David L. Erickson of the National Museum of Natural History, Andrew C. Clarke of Massey University and Daniel H. Sandweiss of the University of Maine. Their work was supported by the Smithsonian Institution and the National Museum of Natural History and by Harvard's Department of Anthropology and Peabody Museum of Archaeology and Ethnology.
Reprinted from:
www.eurekalert.org/pub_releases/2005-12/hu-ahb121305.php
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Skulls in South America Tell New Migration Tale Posted: Monday, December 12, 2005
By Bjorn Carey
LiveScience Staff Writer
For decades it has been believed that the first peoples to populate North and South America crossed over from Siberia by way of the Bering Strait on a land-ice bridge.
However, a new study examining the largest collection of South American skulls ever assembled suggests that a different population may have crossed the bridge to the New World 3,000 years before those Siberians.
Scientists occasionally discover skulls in South America that look more like those belonging to indigenous Australians and Melanesians than Northern Asians, but researchers tend to regard these skulls as anomalies due to natural variation rather than a norm, mainly because there were too few to study.
Now scientists have compared 81 skulls from the Lagoa Santa region of Brazil to worldwide data on human variation.
While the skulls of Native Americans and Northern Asians-the descendents of the early Siberian settlers-generally feature short, wide crania, a broader face, and high, narrow eye sockets and noses, this collection was remarkably different.
The skulls belonging to the earliest known South Americans-or Paleo-Indians-had long, narrow crania, projecting jaws, and low, broad eye sockets and noses. Drastically different from American Indians, these skulls appear more similar to modern Australians, Melanesians, and Sub-Saharan Africans.
Full Article : livescience.com
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