National Geographic Society

The largest-ever study on African genetics has determined that the ancestral origin of humans was probably located in southern Africa, near the South Africa-Namibia border, scientists said today.

African, American, and European researchers working in collaboration over ten years released their study of African genetic data, providing a library of new information on the continent which is thought to be the source of the oldest settlements of modern humans, said a news statement released by the University of Pennsylvania (Penn).

Sarah Tishkoff collects samples in Tanzania. Participants provided information about their ethnicity, language, parents, and grandparents.

Photo courtesy of Sarah Tishkoff

"The study demonstrates startling diversity on the continent, shared ancestry among geographically diverse groups and traces the origins of Africans and African Americans," the statement said. The research is published in the April 30 issue of the journal Science Express.

The yellow shaded area on the border of South Africa and Namibia is the likely ancestral birthplace of modern humans, researchers calculate. The arrow on the Red Sea indicates the likely point where modern humans first left Africa to colonize the rest of the world.

Map courtesy Google Earth

The research team said that its work demonstrated that there is more genetic diversity in Africa than anywhere else on earth.

They analyzed the DNA of more than 3,000 individuals--from 121 African populations, 4 African American populations and 60 non-African populations--to trace the genetic structure of Africans to 14 ancestral population clusters that correlated with ethnicity and shared cultural and/or linguistic properties.

Extrapolating the data, scientists were able to map ancient migrations of populations and determined that the exit point of modern humans out of Africa was near the middle of the Red Sea in East Africa, the news statement added. (See map above.)

Ancient Common Ancestry

"They also provide evidence for ancient common ancestry of geographically diverse hunter-gatherer populations in Africa, including Pygmies from central Africa and click-speaking populations from southern and eastern Africa, suggesting the possibility that the original pygmy language may have contained clicks. Overall, they demonstrate remarkable correspondence between cultural, linguistic, and genetic diversity in Africa."

"This is the largest study to date of African genetic diversity in the nuclear genome," said Sarah Tishkoff, a geneticist with joint appointments in the School of Arts and Sciences and the School of Medicine at the University of Pennsylvania.

"This long term collaboration, involving an international team of researchers and years of research expeditions to collect samples from populations living in remote regions of Africa, has resulted in novel insights about levels and patterns of genetic diversity in Africa, a region that has been underrepresented in human genetic studies.

"Our goal has been to do research that will benefit Africans, both by learning more about their population history and by setting the stage for future genetic studies, including studies of genetic and environmental risk factors for disease and drug response."

Hadza and Datog peoples listen to an explanation of the study in a village near Lake
Eyasi in the Arusha district of northern Tanzania.

Photo courtesy of Sarah Tishkoff

Tishkoff says that there is no single African population that is representative of the diversity present on the continent. Therefore, many ethnically diverse African populations should be included in studies of human genetic variation, disease susceptibility, and drug response.

Anthropologists, historians and linguists now have at their disposal a completely new volume of research with which to test theories of human migration, cultural evolution and population history in Africa, Penn said.

"Basic scientists, physicians and public health officials now have a foundation for illuminating the complex history of Africans and African-Americans, with implications for studies aimed at finding disease genes in these populations and learning which genetic differences make some individuals more susceptible to diseases like HIV, cancer or malaria."

African American Ancestry

The researchers said the study also sheds light on African American ancestry, which they find originates predominantly from western African Niger-Kordofanian (71 percent), European (13 percent), and other African (8 percent) populations, although admixture levels varied considerably among individuals.

These results could have important implications for the design and interpretation of studies which aim to identify genetic and environmental risk factors for diseases common in the African American community, including prostate cancer, hypertension and diabetes.

The first annual "Save The Frogs Day" was declared today, April 28, by a conservation organization set up to generate awareness of the extinction crisis facing many of the world's amphibians.

"The goal is to raise awareness of the rapid disappearance of frog species worldwide," says a news release announcing the event. "Save The Frogs Day events are planned in nearly a dozen countries, including the United States, Canada, Italy, China, and Australia."

The event is organized by Save the Frogs, a nonprofit based in Manassas, Virginia. The charity was founded in May 2008 by Kerry Kriger and scientists, educators, policymakers, and naturalists dedicated to protecting the world's amphibian species through environmental education, scientific research, legal defense and the acquisition of critical habitat.

NGS photo of juvenile tree frog by Paul Zahl

Kriger participated in a research project about the amphibian disease chytridiomycos, funded in part by the National Geographic Society's Committee for Research and Exploration. His work on chytridiomycosis has been published in 15 articles in peer-reviewed international scientific journals. Kriger founded Save the Frogs in May 2008 and is the charity's executive director and only full-time employee.

Nearly one-third of the world's 6,485 amphibian species are threatened with extinction, and at least 150 species have completely disappeared since 1980, and most people don't know about it, Kriger told me in a phone interview.

Save the Frogs Day has been recognized as an official event by Virginia Governor Tim Kaine. "As far as I know, Governor Kaine is the highest-ranking elected official in the world to acknowledge the extinction crisis facing frogs," Kriger said. "Next year I am going to ask everyone to write to their governors and other public representatives. We need to spread the word to the politicians."

Habitat destruction is the primary threat to frogs in lowland areas. But the deadly skin disease caused by a chytrid fungus is spreading through mountainous regions worldwide, driving frog species to extinction within months of its arrival.

NGS photo of hourglass tree frog by Paul Zahl

Millions of frogs are shipped worldwide each year for use as pets or food, and few regulations exist to prevent the transport of infected individuals, the Save the Frogs release says. "Sick frogs inevitably escape into the wild and introduce their disease to places where the native frogs have no evolved defenses. To make matters worse, pesticides and global warming weaken frogs' immune systems, making them more susceptible to infectious diseases."

Kriger hopes that Save The Frogs Day will dramatically increase frog awareness on a global scale.

In recognition of Save The Frogs Day, scientists worldwide will deliver presentations about the amphibian extinction crisis to local schools, zoos and community groups this April 28th. Teachers and students will focus on amphibian conservation, learning about threats to frogs and discussing ways to contribute to conservation efforts. Events for schools also include participating in frog art and frog poetry contests.

Some simple everyday things everyone can do to help save frogs, Kriger says, include not using pesticides in and around the home (chemicals that get into rivers and ponds are not compatible with a healthy ecosystem for frogs), not eating frogs, not buying wild frogs as pets, and lobbying politicians for funding for research and scholarships to train herpetologists.

NGS photo of reed frog by Michael Nichols

Ultimately, Kriger wants to see funding to buy critical habitat for frogs and laws passed to protect amphibians. "This is one of the most significant environmental issues of the 21st century," he says. "Unless we act quickly, amphibian species will continue to disappear, resulting in irreversible consequences to Earth's ecosystems and to humans."

NGS photo of harlequin tree frogs by Paul Zahl

 

How to Help (Save the Frogs Web site tips and advice on what you can do to save frogs.)

Related NatGeo News Watch entries:

Bait Shops Found to Be Spreading Chytrid and Other Amphibian Diseases

Green-and-Black Golden Frog Born at Bronx Zoo

Are Humans Now Eating Frogs to Extinction?

Four out of Ten Amphibians in Decline, New Study Finds

All blog entries about frogs

WCS photo by Alex Dehgan

One of Afghanistan's best-known natural areas--a spectacular series of six deep blue lakes separated by natural dams made of travertine, a mineral deposit--has been declared the country's first national park.

The park is near the Bamyan Valley, where the 1,500-year-old giant Buddha statues destroyed by the Taliban once stood.

"Travertine systems are found in only a few places throughout the world, virtually all of which are on the UNESCO World Heritage list and are major international tourist attractions," the New York-based Wildlife Conservation Society said in a news release announcing the new national park. WCS worked with the Afghanistan government and the United States Agency for International Development (USAID) to establish Band-e-Amir national park.

WCS scientist Chris Shank with two Afghan park guards

WCS photo by Chris Shank

USAID provided key funding that led to the park's creation, including support of WCS to conduct preliminary wildlife surveys, identify and delineate the park's boundaries, and work with local communities and the provincial government, WCS said in a news statement. WCS also developed the park's management plan, helped the government hire and train local rangers, and provided assistance to the Afghan Government to design the laws enabling the park to be created.

"At its core, Band-e-Amir is an Afghan initiative supported by the international community. It is a park created for Afghans, by Afghans, for the new Afghanistan," said Steven E. Sanderson, president and CEO of the Wildlife Conservation Society. "Band-e-Amir will be Afghanistan's first national park and sets the precedent for a future national park system."

WCS photo by Chris Shank

Band-e-Amir had been a destination for travelers since the 1950s, with a peak visitation in the 1970s, WCS added. Tourism was almost entirely absent during the war years between 1979-2001. "Today, Band-e-Amir is visited every year by thousands of Afghan tourists and religious pilgrims as well as many foreigners currently living and working in-country."

Though much of the park's wildlife has been lost, WCS said, recent surveys indicate that it still contains ibex (a species of wild goat) and urial (a type of wild sheep) along with wolves, foxes, smaller mammals and fish, and various bird species including the Afghan snow finch, which is believed to be the only bird found exclusively in Afghanistan. "Snow leopards were once found in the area but vanished due to hunting in the early 1980s."

Fragile Travertine Dams

The llakes are under growing threat from pollution and other human-caused degradation to the fragile travertine dams.

Creating the national park will provide international recognition essential to helping develop Band-e-Amir as an international tourist destination, and assist it in obtaining World Heritage status, which would provide additional protection, according to WCS. "It also sets the groundwork to create an Afghan Protected Area System that could include the wildlife-rich transboundary area in the Pamirs shared by Afghanistan, Pakistan, China and Tajikistan."

The new park will be managed by Afghanistan's National Environmental Protection Agency, the Ministry of Agriculture, Irrigation and Livestock, and the Band-e-Amir Protected Area Committee.

WCS helped the 13 villages lying within the park establish this committee, which provides local input into all management decisions. "The park will provide employment, tourism-derived revenue, and ensure that local communities play a key role in protecting this world class landscape," WCS said.

One of the travertine dams that make up the series of six lakes. Note the person standing on top of the dam.

WCS photo by Chris Shank

Large, often barren, tropical trees stand where they once grew when the area was in severe drought and water levels in Lake Bosumtwi in Ghana had bottomed out. Submerged in 50-65 feet (15-20 meters) of water, the trees are stark reminders of severe, long lasting dry spells from just a few centuries ago.

Photo by J.T. Overpeck and W. Wheeler, University of Arizona.

A new study of lake sediments in Ghana suggests that severe droughts lasting several decades, even centuries, were the norm in West Africa over the past 3,000 years, University of Arizona scientists said today. The current bout of planetary warming could mean that future conditions in the region will favor even more extreme droughts, they added.

"The earlier dry spells dwarfed the well-documented drought that plagued West Africa in the late-20th century, and as the planet warms, the study's authors believe the region's rainfall patterns will have an even greater impact," Arizona said in a news statement.

The team of geoscientists and climate scientists, led by Jonathan Overpeck of the University of Arizona and his former doctoral student, lead author Timothy Shanahan, who is now at the University of Texas (UT) at Austin, announced their findings in the April 17, 2009, issue of Science.

Because of close agreement amongst several data sets, the scientists believe the droughts are driven in part by circulation of the ocean and atmosphere in and above the Atlantic--and possibly beyond, the news release said. "If climate models for such circulation patterns hold true, the study suggests global warming could create conditions that favor extreme droughts."

"Clearly, much of West Africa is already on the edge of sustainability," Overpeck says, "and the situation could become much more dire in the future with increased global warming."

The findings emerged from sediments that lie at the bottom of Lake Bosumtwi in Ghana, deposits of soil and organic matter that contain annual bands of light (winter) and dark (summer) layers that stretch back more than three millennia, Arizona University said. Oxygen (O) isotopes in calcium carbonate from the sediment provided a detailed record of dry and wet periods. Higher concentrations of common 16O indicated greater rainfall, while higher concentrations of slightly heavier, and therefore harder to evaporate, 18O indicated periods of drier conditions and drought.

"Lake Bosumtwi is really unique in that its one of the few locations in tropical West Africa where varves, annual sediment layers, are preserved. This allows us to look at changes in climate at very high resolution," said Shanahan, now an assistant professor at UT.

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The National Science Foundation (NSF) today announced a U.S.$48 million partnership with the Bill & Melinda Gates Foundation to support innovative solutions to critical agricultural challenges in developing countries.

Each organization will provide $24 million over five years to support a competitive awards program for science research projects that address drought, pests, disease and other serious problems facing small farmers and their families who rely on their crops for their food and income, the NSF said in a news release.

The award program will be called BREAD--Basic Research to Enable Agricultural Development--and will support a competitive award program for science research projects that develop innovative approaches and technologies to boost agricultural productivity in developing countries.

NGS photo of Nigerian woman carrying cassava by Lynn Johnson

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