2/09/2006
Three human migrations out of Africa
By Tony Fitzpatrick
A new, more robust analysis of recently derived human gene trees by Alan R. Templeton, Ph.D, of Washington University in St Louis, shows three distinct major waves of human migration out of Africa instead of just two, and statistically refutes — strongly — the 'Out of Africa' replacement theory.
That theory holds that populations of Homo sapiens left Africa 100,000 years ago and wiped out existing populations of humans. Templeton has shown that the African populations interbred with the Eurasian populations.
Templeton's analysis is considered to be the only definitive statistical test to refute the theory, dominant in human evolution science for more than two decades.
"Not only does the new analysis reject the theory, it demolishes it," Templeton said.
He used a computer program called GEODIS, which he created in 1995 and later modified with the help of David Posada, Ph.D., and Keith Crandall, Ph.D. at Brigham Young University, to determine genetic relationships among and within populations based on an examination of specific haplotypes, clusters of genes that are inherited as a unit.
In 2002, Templeton analyzed ten different haplotype trees and performed phylogeographic analyses that reconstructed the history of the species through space and time.
Populations of Homo erectus in Eurasia had recurrent genetic interchange with African populations 1.5 million years ago, much earlier than previously thought, and that these populations persisted instead of going extinct, which some human evolution researchers thought had occurred.
"By the time you're done with this phase you can be 99 percent confident that there was recurrent genetic interchange between African and Eurasian populations," he said. "So the idea of pure, distinct races in humans does not exist. We humans don't have a tree relationship, rather a trellis. We're intertwined."
New analysis shows three human migrations out of Africa
A new, more robust analysis of recently derived human gene trees by Alan R. Templeton, Ph.D, of Washington University in St Louis, shows three distinct major waves of human migration out of Africa instead of just two, and statistically refutes — strongly — the 'Out of Africa' replacement theory.
That theory holds that populations of Homo sapiens left Africa 100,000 years ago and wiped out existing populations of humans. Templeton has shown that the African populations interbred with the Eurasian populations.
Templeton's analysis is considered to be the only definitive statistical test to refute the theory, dominant in human evolution science for more than two decades."Not only does the new analysis reject the theory, it demolishes it," Templeton said.
He used a computer program called GEODIS, which he created in 1995 and later modified with the help of David Posada, Ph.D., and Keith Crandall, Ph.D. at Brigham Young University, to determine genetic relationships among and within populations based on an examination of specific haplotypes, clusters of genes that are inherited as a unit.
In 2002, Templeton analyzed ten different haplotype trees and performed phylogeographic analyses that reconstructed the history of the species through space and time.
Populations of Homo erectus in Eurasia had recurrent genetic interchange with African populations 1.5 million years ago, much earlier than previously thought, and that these populations persisted instead of going extinct, which some human evolution researchers thought had occurred.
"By the time you're done with this phase you can be 99 percent confident that there was recurrent genetic interchange between African and Eurasian populations," he said. "So the idea of pure, distinct races in humans does not exist. We humans don't have a tree relationship, rather a trellis. We're intertwined."
New analysis shows three human migrations out of Africa
Nutrigenomics
Nutrigenomics experts worldwide have aligned, and they are calling for teamwork. José Ordovas, PhD, director of the Nutrition and Genomics Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University joined more than eighty other leading researchers in the fields of nutrition and genetics to co-author a report outlining their strategy for maximizing the impact of nutrigenomics research on global poverty and health.
As Jim Kaput, PhD, of University of California, Davis, Ordovas, and their many colleagues write in the British Journal of Nutrition, their goal is to create an international consortium with which to harness the power and expertise of a large collaborative network of nutritional genomics researchers dedicated to investigating how genetics and nutrition can promote health or prevent disease.
"Advancing our knowledge of diet-gene interactions is critical," says Ordovas, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts, "but knowledge alone is not sufficient for us to effectively address health disparities and combat chronic disease throughout the world." He emphasizes that scientists must collaborate with scholars and policy makers, as well.
Potential benefits include developing new diagnostic tests for adverse responses to food, identifying specific populations of people who have special nutrient needs, revealing previously undiscovered nutrient-gene interactions, improving current methods for dietary assessment, and assisting in creating more nutritious foods and formulations.
Since some racial and ethnic populations suffer disproportionately from specific chronic diseases, it is important that they are included as participants in nutrigenomic research studies. The consortium proposes the development of protocols to address the ethical, social and legal issues of study sponsorship and benefit sharing, public engagement, consent, and data protection.
The future of nutritional genomics is collaboration
As Jim Kaput, PhD, of University of California, Davis, Ordovas, and their many colleagues write in the British Journal of Nutrition, their goal is to create an international consortium with which to harness the power and expertise of a large collaborative network of nutritional genomics researchers dedicated to investigating how genetics and nutrition can promote health or prevent disease.
"Advancing our knowledge of diet-gene interactions is critical," says Ordovas, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts, "but knowledge alone is not sufficient for us to effectively address health disparities and combat chronic disease throughout the world." He emphasizes that scientists must collaborate with scholars and policy makers, as well.
Potential benefits include developing new diagnostic tests for adverse responses to food, identifying specific populations of people who have special nutrient needs, revealing previously undiscovered nutrient-gene interactions, improving current methods for dietary assessment, and assisting in creating more nutritious foods and formulations.
Since some racial and ethnic populations suffer disproportionately from specific chronic diseases, it is important that they are included as participants in nutrigenomic research studies. The consortium proposes the development of protocols to address the ethical, social and legal issues of study sponsorship and benefit sharing, public engagement, consent, and data protection.
The future of nutritional genomics is collaboration
Weight-Loss Resistance Gene
Two obese people follow the same low-calorie diet and do not exercise, but one loses much more weight than the other. Genetic factors may explain this phenomenon, according to Jose Ordovas, PhD, director of the Nutrition and Genomics Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. In a study published in the Journal of Clinical Endocrinology & Metabolism, Ordovas and colleagues identified a variation in the perilipin gene that appears to render some people resistant to weight loss from calorie restriction. This research builds on their earlier work on perilipin and obesity.
Friedman Nutrition Notes: November / December 2005
Friedman Nutrition Notes: November / December 2005
2/06/2006
Ancestry Tracing basics
Good article in NYT by Jennifer Alserver with basics about tracing your ancestry using DNA analysis:
The DNA tests have limitations, showing only small slices of genetic history.
Here is why: a popular test, the Y-DNA, analyzes the Y chromosome that is passed virtually unchanged for generations from father to son. The test, which can be taken only by men, examines just one branch of a family tree: the male line — a father's father's father, and so on.
Another test looks at mitochondrial DNA, a certain form that is passed from a mother to all her children. Both men and women can take the test, which aims to trace ancestors on a mother's side. But the test follows only the direct female line.
Both tests are used to determine if people are related, even through people who lived 500 years ago, or perhaps determine the country of their ancestors. No test can look at the DNA of a father's mother, for instance, or of a mother's father.
The tests generally work this way: A person orders a test online and receives a kit with toothbrushlike scrapers, collection tubes and instructions on how to take a swab from inside the cheek. The samples are mailed to a laboratory, where scientists analyze DNA markers, or genetic traits.
The results and samples, sometimes labeled with bar codes to protect identities, are stored for future tests unless customers request that they be destroyed. Consumers worried about privacy should ask questions of the testing company and satisfy themselves that the provider respects confidentiality.
DNA Kits Aim to Link You to the Here and Then - New York Times
The DNA tests have limitations, showing only small slices of genetic history.
Here is why: a popular test, the Y-DNA, analyzes the Y chromosome that is passed virtually unchanged for generations from father to son. The test, which can be taken only by men, examines just one branch of a family tree: the male line — a father's father's father, and so on.
Another test looks at mitochondrial DNA, a certain form that is passed from a mother to all her children. Both men and women can take the test, which aims to trace ancestors on a mother's side. But the test follows only the direct female line.
Both tests are used to determine if people are related, even through people who lived 500 years ago, or perhaps determine the country of their ancestors. No test can look at the DNA of a father's mother, for instance, or of a mother's father.
The tests generally work this way: A person orders a test online and receives a kit with toothbrushlike scrapers, collection tubes and instructions on how to take a swab from inside the cheek. The samples are mailed to a laboratory, where scientists analyze DNA markers, or genetic traits.
The results and samples, sometimes labeled with bar codes to protect identities, are stored for future tests unless customers request that they be destroyed. Consumers worried about privacy should ask questions of the testing company and satisfy themselves that the provider respects confidentiality.
DNA Kits Aim to Link You to the Here and Then - New York Times
