Saturday, February 11, 2006


Space rock re-opens Life on Mars debate

BBC News

A carbon-rich substance found filling tiny cracks within a Martian meteorite could boost the idea that life once existed on the Red Planet.

The material resembles that found in fractures, or "veins", apparently etched by microbes in volcanic glass from the Earth's ocean floor.

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Friday, February 10, 2006


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 - thus, making love, not war.

"The 'Out of Africa' replacement theory has always been a big controversy," Templeton said. "I set up a null hypothesis and the program rejected that hypothesis using the new data with a probability level of 10 to the minus 17th. In science, you don't get any more conclusive than that. It says that the hypothesis of no interbreeding is so grossly incompatible with the data, that you can reject it."

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.

Templeton published his results in the Yearbook of Physical Anthropology, 2005.

A trellis, not a tree

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.

Three years later, he had 25 regions to analyze and the data provided molecular evidence of a third migration, this one the oldest, back to 1.9 million years ago.

"This time frame corresponds extremely well with the fossil record, which shows Homo erectus expanding out of Africa then," Templeton said.

Another novel find is that 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.

The new data confirm an expansion out of Africa to 700,000 years ago that was detected in the 2002 analysis.

"Both (the 1.9 million and 700,000 year) expansions coincide with recent paleoclimatic data that indicate periods of very high rainfall in eastern Africa, making what is now the Sahara Desert a savannah," Templeton said. "That makes the timing very amenable for movements of large populations through the area."

Templeton said that the fossil record indicates a significant change in brain size for modern humans at 700,000 years ago as well as the adaptation and expansion of a new stone tool culture first found in Africa and later at 700,000 years expanded throughout Eurasia.

"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.

Source: Washington University in St. Louis News and Information February 2, 2006


[1] Haplotype trees and modern human origins
Templeton AR

Am J Phys Anthropol. 2005;Suppl 41:33-59

A haplotype is a multisite haploid genotype at two or more polymorphic sites on the same chromosome in a defined DNA region. An evolutionary tree of the haplotypes can be estimated if the DNA region had little to no recombination. Haplotype trees can be used to reconstruct past human gene-flow patterns and historical events, but any single tree captures only a small portion of evolutionary history, and is subject to error. A fuller view of human evolution requires multiple DNA regions, and errors can be minimized by cross-validating inferences across loci. An analysis of 25 DNA regions reveals an out-of-Africa expansion event at 1.9 million years ago. Gene flow with isolation by distance was established between African and Eurasian populations by about 1.5 million years ago, with no detectable interruptions since. A second out-of-Africa expansion occurred about 700,000 years ago, and involved interbreeding with at least some Eurasian populations. A third out-of-Africa event occurred around 100,000 years ago, and was also characterized by interbreeding, with the hypothesis of a total Eurasian replacement strongly rejected (P less than 10(-17)). This does not preclude the possibility that some Eurasian populations could have been replaced, and the status of Neanderthals is indecisive. Demographic inferences from haplotype trees have been inconsistent, so few definitive conclusions can be made at this time. Haplotype trees from human parasites offer additional insights into human evolution and raise the possibility of an Asian isolate of humanity, but once again not in a definitive fashion. Haplotype trees can also indicate which genes were subject to positive selection in the lineage leading to modern humans. Genetics provides many insights into human evolution, but those insights need to be integrated with fossil and archaeological data to yield a fuller picture of the origin of modern humans.


Related posts include:

"Out of Africa - Bacteria, as well (Helicobacter pylori)"

"Artefacts support theory man came from Africa"

"Hofmeyr Skull Is First Fossil Proof of Human Migration Theory"

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[Gen] Science losing war over evolution (Harvard Gazette)

[Powell, Harvard University News Office, Feb '06]

Screening airs evolution versus intelligent design debate

This just in from the front lines of the battle between evolution and intelligent design: evolution is losing.

That's the assessment of Randy Olson, a Harvard-trained evolutionary biologist turned filmmaker who explored the debate in a new film, "Flock of Dodos: The Evolution - Intelligent Design Circus," which was screened Monday (Feb. 6) at the Harvard Museum of Natural History.

Full text at:


Model of an Internal Evolutionary Mechanism

Featured book: "Flock of Dodos: Behind Modern Creationism and Intelligent Design" (Amazon UK | US)

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Wednesday, February 08, 2006


Scientists Force Viruses To Evolve As Better Delivery Vehicles For Gene Therapy

Viruses and humans have evolved together over millions of years in a game of one-upmanship that, often as not, left humans sick or worse.

Now, a University of California, Berkeley, researcher has shown that viruses - in this case, a benign one - can be forced to evolve in ways to benefit humans.

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New Scientist Breaking News - T. rex's great-grandfather unearthed in China

"The earliest tyrannosaur - the great-grandfather of the fearsome Tyrannosaurus rex - has been unearthed in a desert in China.

Dubbed Guanlong, meaning "crowned dragon", the oldest known tyrannosauroid lived about 160 million years ago in northwestern China and was at the base of the evolutionary tree leading to the tyrant lizard king, T. rex.

Researchers found the nearly complete skeleton of a juvenile and the partial skeleton of a 3-metre-long adult in a former wetland in what is now the Gobi Desert. The juvenile died first and its skeleton sank into the mud where it may later have been walked over by the adult before it died, says Xing Xu of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, who led the team."

Books on Dinosaurs from the Science and Evolution Bookshop: UK | US

Books on Paleontology from the Science and Evolution Bookshop: UK | US

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Scientists Sequence Complete Genome of Woolly Mammoth

"Scientists have completed the oldest mitochondrial genome sequence from the 33,000-year-old remains of a woolly mammoth; results show mammoths and Asian elephants are a sister species that diverged soon after their common ancestor split from the lineage of the African elephant.

Some 10,000 years after the last of their kind wandered the North American and Eurasian wilderness, woolly mammoths (Mammuthus primigenius) remain a fascinating subject of study for scientists, with implications for understanding the evolutionary origins of present day mammals. Mammoths and elephants belong to one of the most ancient mammalian groups and various recent studies have debated the genetic relationships between them. Now, scientists at the University of Massachusetts Medical School and the Russian Academy of Medical Sciences have weighed in on the issue, with results supported by the oldest mitochondrial genome sequence determined to date from the remains of a mammoth that died approximately 33,000 years ago."

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Cancer researchers found a new mechanism potentially explaining

Cancer researchers at the University of Helsinki, Finland, in trying to find a novel tumor suppressor gene, instead found an important evolutionary change that occurred in a key developmental signalling pathway. The finding suggests a potential mechanism for evolution of complex intercellular signalling pathways. The results are published in today’s issue of the journal Developmental Cell.

Full text at:


Model of an Internal Evolutionary Mechanism

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The Human Genome Project +5 (The Scientist)

The Human Genome Project +5

Five years after publication of two drafts of the human genome, Maynard Olson of the University of Washington finds himself longing for another "lurch." To be sure, genomic scientists across the world have chalked up many achievements since 2001, but, like many of his colleagues, Olson is feeling more impatient than celebratory.

Full text at:


Model of an Internal Evolutionary Mechanism

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Tuesday, February 07, 2006


New species found in Papua 'Eden'

An international team of scientists says it has found a "lost world" in the Indonesian jungle that is home to dozens of new animal and plant species.

"It's as close to the Garden of Eden as you're going to find on Earth," said Bruce Beehler, co-leader of the group.

The team recorded new butterflies, frogs, and a series of remarkable plants that included five new palms and a giant rhododendron flower.

The survey also found a honeyeater bird that was previously unknown to science.

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