[ Back to EurekAlert! ] Public release date: 6-Dec-2011
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Contact: PNAS News Office
Proceedings of the National Academy of Sciences

European colonization and Native American populations

A genetic study suggests that indigenous Americans experienced a significant contraction in population size some 500 years ago, coincident with European colonization. Brendan O'Fallon and Lars Fehren-Schmitz analyzed ancient and contemporary mitochondrial DNA to construct a demographic history of indigenous Americans. While archeological and historical records indicate that European contact resulted in widespread Native American mortality from various sources including warfare, enslavement, and disease, genetic studies had so far found little evidence of a recent decrease in Native American population size. The authors studied a large genetic dataset and identified several distinct demographic epochs, with a rapid expansion of Native American populations roughly 8,000-12,000 years ago followed by a long period of demographic stability. About 500 years ago, the indigenous American population decreased substantially, with the number of females reduced to about 50% of the pre-decline peak nearly 5,000 years ago. The population size remained low for several hundred years after the recent decline, though it eventually returned to levels similar to those before the event, the authors report. The results are consistent with historical records indicating that European colonization reduced the size of indigenous American populations, and the scale of the estimated contraction suggests that this decrease was not localized to particular regions or communities, according to the authors.

Article #11-12563: "Native Americans experienced a strong population bottleneck coincident with European contact," by Brendan O'Fallon and Lars Fehren-Schmitz
MEDIA CONTACT: Brendan O'Fallon, University of Washington, Seattle, WA; tel: 801-556-8527 (day), 801-556-8527 (evening); e-mail: brendano@u.washington.edu



Rice consumption and arsenic

In a study of more than 200 pregnant women who received prenatal care near New Hampshire, researchers report a link between rice consumption and the excretion of potentially harmful levels of arsenic in urine.

Article #11-09127: "Rice consumption contributes to arsenic exposure in U.S. women," by Diane Gilbert-Diamond et al.

MEDIA CONTACT: Diane Gilbert-Diamond, Department of Community and Family Medicine, Dartmouth Medical School, Lebanon, NH; tel: 603-653-3362; e-mail: Diane.Gilbert-Diamond@Dartmouth.edu


Tuna populations dwindling

Researchers report that the global tuna population shrunk by about 60% over the last 50 years due in part to overfishing, which could potentially jeopardize the stability of marine ecosystems in the absence of sustainable management measures.

Article #11-07743: "Global population trajectories of tunas and their relatives," by Maria José Juan-Jordá, Iago Mosqueira, Andrew B. Cooper, Juan Freire, and Nicholas K. Dulvy

MEDIA CONTACT: Maria José Juan-Jordá, Grupo de Recursos Marinos y Pesquerías, Universidad de A Coruña, A Coruña, SPAIN; tel: +34-981167000 ext. 2204; e-mail: m.juan.jorda@udc.es


Gene variant associated with risk of multiple sclerosis

A study of 264 patients with multiple sclerosis and 301 healthy participants revealed a genetic variant associated with the risk and progression of the debilitating disease.

Article #11-11867: "An SP1-binding CD24 promoter variant strongly associates with risk and progression of multiple sclerosis," by Lizhong Wang et al.

MEDIA CONTACT: Yang Liu; University of Michigan, Ann Arbor, MI; tel: 734-615-3158; e-mail: yangl@umich.edu


Chimps associate sounds with colors, too

A study reveals that chimpanzees, like humans, inherently associate high pitch sounds with light colors and low pitch sounds with dark colors, suggesting that this pattern may be a basic feature of the primate sensory system rather than a culturally learned or linguistic phenomenon.

Article #11-12605: "Visuo-auditory mappings between high luminance and high pitch are shared by chimpanzees (Pan troglodytes) and humans," by Vera U. Ludwig, Ikuma Adachi, and Tetsuro Matsuzawa

MEDIA CONTACT: Verg Ludwig, Division of Mind and Brain Research, Department of Psychiatry and Psychotherapy, Charité University Medicine Berlin, Berlin, GERMANY; tel: +49-30-450-517235 (primary), +49-15-778-256677 (secondary); e-mail: Vera.Ludwig@charite.de


Success of invasive fire ant traced to partnership

The red fire ant Solenopsis invicta, a notorious agricultural pest and invasive species imported into the United States from Argentina, partly owes its successful spread to mutually beneficial interactions with honeydew-producing insects such as cicadas and aphids, according to a study.

Article #11-15263: "Intercontinental differences in resource use reveal the importance of mutualisms in fire ant invasions," by Shawn M. Wilder, David A. Holway, Andrew V. Suarez, Edward G. LeBrun, and Micky D. Eubanks

MEDIA CONTACT: Shawn M. Wilder, Department of Entomology, Texas A&M University, College Station, TX; tel: +043-702-7753; e-mail: wilder.shawn@gmail.com


Air capture of CO2 may be too costly to be practical

Capturing CO2 from the air--a proposed option for reducing global atmospheric CO2 levels--may be more expensive and energy-consuming than other mainstream CO2 mitigation strategies such as renewable energy, nuclear power, and carbon dioxide capture and storage from large CO2-emitting sources, according to a study that analyzed the economic and energetic costs of existing CO2 air capture systems.

Article #10-12253: "An economic and energetic analysis of capturing CO2 from ambient air," by Kurt Z. House, Antonio C. Baclig, Manya Ranjan, Ernst A. van Nierop, Jennifer Wilcox, and Howard J. Herzog

MEDIA CONTACT: Ernst A. van Nierop, C12 Energy, Cambridge, MA; tel: 617-849-8006 (primary), 617-413-4638 (secondary); e-mail: ernst@c12energy.com


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