Maize May Have Been Domesticated In Mexico As Early As 10,000 Years Ago

Things just keep getting pushed back…

Maize (Corn) May Have Been Domesticated In Mexico As Early As 10,000 Years Ago [Science Daily]

The ancestors of maize originally grew wild in Mexico and were radically different from the plant that is now one of the most important crops in the world. While the evidence is clear that maize was first domesticated in Mexico, the time and location of the earliest domestication and dispersal events are still in dispute.

Now, in addition to more traditional macrobotanical and archeological remains, scientists are using new genetic and microbotanical techniques to distinguish domesticated maize from its wild relatives as well as to identify ancient sites of maize agriculture. These new analyses suggest that maize may have been domesticated in Mexico as early as 10,000 years ago.

Dr. John Jones and his colleagues, Mary Pohl, and Kevin Pope, have evaluated multiple lines of evidence, including paleobotanical remains such as pollen, phytoliths, and starch grains, as well as genetic analyses, to reconstruct the early history of maize agriculture. Dr. Jones, of the Department of Anthropology, Washington State University, Pullman, will be presenting this work at a symposium on Maize Biology at the annual meeting of the American Society of Plant Biologists in Mérida, Mexico (June 28, 2008). [more]

Woolly-Mammoth Gene Study Changes Extinction Theory

More fodder, more grist for that mill.

Woolly-Mammoth Gene Study Changes Extinction Theory

Credit: Penn State
by Staff Writers
University Park PA (SPX) Jun 13, 2008
A large genetic study of the extinct woolly mammoth has revealed that the species was not one large homogenous [sic–ed.] group, as scientists previously had assumed, and that it did not have much genetic diversity.

“The population was split into two groups, then one of the groups died out 45,000 years ago, long before the first humans began to appear in the region,” said Stephan C. Schuster, associate professor of biochemistry and molecular biology at Penn State University and a leader of the research team.

“This discovery is particularly interesting because it rules out human hunting as a contributing factor, leaving climate change and disease as the most probable causes of extinction.” The discovery will be published later this week in the early online edition of the Proceedings of the National Academy of Sciences (PNAS).
The research marks the first time scientists have dissected the structure of an entire population of extinct mammal by using the complete mitochondrial genome — all the DNA that makes up all the genes found in the mitochondria structures within cells.

Data from this study will enable testing of the new hypothesis presented by the team, that there were two groups of woolly mammoth — a concept that previously had not been recognized from studies of the fossil record.

The scientists analyzed the genes in hair obtained from individual woolly mammoths — an extinct species of elephant adapted to living in the cold environment of the northern hemisphere. The bodies of these mammoths were found throughout a wide swathe of northern Siberia. Their dates of death span roughly 47,000 years, ranging from about 13,000 years ago to about 60,000 years ago.

Schuster and Webb Miller, professor of biology and computer science and engineering at Penn State, led the international research team, which includes Thomas Gilbert at the University of Copenhagen in Denmark and other scientists in Australia, Belgium, France, Italy, Russia, Spain, Sweden, the United Kingdom, and the United States.

The team includes experts in the fields of genome evolution, ancient DNA, and mammoth paleontology, as well as curators from various natural-history museums.
Another important finding for understanding the extinction processes is that the individuals in each of the two woolly-mammoth groups were related very closely to one another. “This low genetic divergence is surprising because the woolly mammoth had an extraordinarily wide range: from Western Europe, to the Bering Strait in Siberia, to Northern America,” Miller said.

“The low genetic divergence of mammoth, which we discovered, may have degraded the biological fitness of these animals in a time of changing environments and other challenges.”
Our study suggests a genetic divergence of the two woolly-mammoth groups more than 1-million years ago, which is one quarter the genetic distance that separates Indian and African elephants and woolly mammoths,” Miller said. The research indicates that the diversity of the two woolly-mammoth populations was as low centuries ago as it is now in the very small populations of Asian elephants living in southern India.

“The low genetic divergence of the elephants in southern Indian has been suggested as contributing to the problems of maintaining this group as a thriving population,” Schuster said. Intriguingly, the mitochondrial genomes revealed by the researchers are several times more complete than those known for the modern Indian and African Elephants combined.

Whereas studies before this research had analyzed only short segments of the DNA of extinct species, this new study generated and compared 18 complete genomes of the extinct woolly mammoth using mitochondrial DNA, an important material for studying ancient genes.

This achievement is based on an earlier discovery of the team led by Miller, Schuster, and co-author Thomas Gilbert, which was published last year and that revealed ancient DNA survives much better in hair than in any other tissue investigated so far.
This discovery makes hair, when it is available, a more powerful and efficient source of DNA for studying the genome sequences of extinct animals. Moreover, mammoth hair is found in copious quantities in cold environments and it is not regarded as fossil material of enormous value like bone or muscle, which also carries anatomical information.

“We also discovered that the DNA in hair shafts is remarkably enriched for mitochondrial DNA, the special type of DNA frequently used to measure the genetic diversity of a population,” Miller said. The team’s earlier study also showed that hair is superior for use in molecular-genetic analysis because it is much easier than bone to decontaminate.

Not only is hair easily cleaned of external contamination such as bacteria and fungi, its structure also protects it from degradation, preventing internal penetration by microorganisms in the environment.

An important aspect of the new study is that the hair samples it used had been stored in various museums for many years before being analyzed by the researchers, yet the scientists were able to obtain lots of useful DNA from them. “One of our samples originates from the famous Adams mammoth, which was found in 1799 and has been stored at room temperatures for the last 200 years,” Schuster said.

This research technique opens the door for future projects to target interesting specimens that were collected a long time ago and are no longer available from modern species, the scientists said. Even the molecular analysis of entire collections seems now possible, an effort that the team calls “Museomics.”

“We plan to continue using our techniques to untangle the secrets of populations that lived long ago and to learn what it might have taken for them to survive,” Schuster said. “Many of us also have a personal interest in learning as much as we can about how any species of large mammal can go extinct.”
The research was supported, in large part, by Penn State University, Roche Applied Sciences, and a private sponsor. Additional support was provided by the National Human Genome Research Institute, Marie Curie Actions, the Australian Research Council, the Russian Foundation for Basic Research, and the Pennsylvania Department of Health. [via ARCH-L]

Well, it largely rules out hunting in the 45KYA extinction. Probably. 😉

Let’s see how the use of DNA from hair holds up. That’s a factor, too. Though this appearing in the National Academy of Sciences is heartening, as that implies it has gone through the initial vetting process.

Custer Died for Your Sins

on this day in 1876 at the Battle of the Little Bighorn / Custer’s Last Stand / the Battle of the Greasy Grass thanks to the efforts of Sitting Bull, Crazy Horse, Lame Deer (the older one) and many others. Go have a pig roast or something…

The place of the battle is quite impressive if you’re ever in that neck of the woods.

links for 2008-03-08

links for 2008-02-18

links for 2008-01-26

Merry Christmas 2007

After leaving chocolate-chip cookies and milk for Santa and carrots for his reindeer, we awoke this morning and have watched an exuberant six-year-old unwrap far too many presents (our bad) and settle down, unsurprisingly, with one of the least expensive and uncomplicated gifts of the year. A old-fashioned wooden pop-gun — you know — with a cork on a string that goes “pop!” when you pump it.

Great fun, especially after ‘don’t be a space invader’ policies were reiterated. He’s a good boy, we didn’t even have to tell him to leave the cats alone. My personal favorite of his? The microscope.

Audrey gave me Paleoindian or Paleoarchaic?: Great Basin Human Ecology at the Pleistocene-Holocene Transition, The Adventures of Young Indiana Jones, Vol. Two – The War Years, slide guitar for rock & blues instructional DVD and a lava lamp! Life is gooooood.

We hope you’re having a great day whether it is Christmas, Santa Claus Day, Newtonmas or just December 25.