National Geographic Society

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.

Hissing cockroach picture courtesy Ohio State University

Mites living on Madagascar hissing cockroaches help decrease the presence of a variety of molds on the cockroaches' bodies, potentially reducing allergic responses among humans who handle the popular insects, according to Ohio State University.

Scientists cultured and identified fungi on the cockroaches' body surfaces with and without mites and discovered that the presence of these mites reduced the molds by at least 50 percent, the university said in a news release today.

"Many of these same researchers reported a year ago that 14 different types of mold were present on and around this species of cockroach, including several fungi associated with allergies and others that can cause secondary infections if they enter the lungs or an open wound," the release said.

The mites eat saliva and organic debris that collects between the cockroaches' legs, eliminating material that would foster mold growth on the insects' bodies. The mites don't appear to actually eat any mold.

"We haven't proved yet that this helps the cockroaches, but reducing the fungi present on their surface is beneficial overall," said Joshua Benoit, a doctoral student in entomology at Ohio State and a co-author of the study. "By suppressing the molds, the mites have a role in reducing allergic reactions to cockroaches."

The research is published in the current issue of the journal Symbiosis.

he Madagascar hissing cockroach, or Gromphadorhina portentosa, grows to between 2 and 3 inches long and 1 inch wide, and makes its characteristic hissing sound if it is squeezed or otherwise feels threatened, the news release said. "Its gentle nature, large size, odd sounds and low-maintenance care have made the species a popular educational tool and pet for years."

Photo of mites on Madagascar hissing cockroach courtesy Ohio State University

When Benoit and colleagues discovered the molds on cockroach surfaces in a previous study, they recommended that people wash their hands after handling the cockroaches and emphasized the need to keep the insects' cages clean. Because the mites do not completely eliminate fungi, the researchers continue to recommend that people sensitive to molds use care in handling Madagascar hissing cockroaches.

"It turns out that not all colonies of Madagascar hissing cockroaches harbor the mites, a species called Gromphadorholaelaps schaeferi. Researchers do not know why that is," the release said. "But the cockroaches that do harbor mites also harbor fewer molds on their bodies."

In the study, female cockroaches with mites had 64 percent fewer fungal colonies than those lacking mites. In males, the difference was 31 percent, and in nymphs, or younger and smaller cockroaches, there were 24 percent fewer fungi.

"The presence of the mites caused a reduction in all fungi on the surface, not just a select few kinds of fungus," said Jay Yoder, a professor of biology at Wittenberg University and lead author of the study.

About 20 to 25 mites live on each adult cockroach. The scientists experimented by adding more mites to the insects' surfaces, but found that more mites didn't result in a more significant reduction in molds.

"The number on each insect is based on the food available," Benoit said.

In captivity, Madagascar hissing cockroaches thrive on dog food and fruit. Benoit said they tend to slobber on themselves when they eat, leaving saliva and organic debris in crevices along the lower middle portions of their bodies for the mites to eat. The mites are in particular need of the moisture in the food--meaning they eat up water and nutrients that molds need to establish themselves and grow.

"The mites also obtain moisture from spiracles through which the cockroaches breathe," the release added. "The mites cannot live anywhere else but on the surface of the Madagascar hissing cockroach. Chemical cues from growing nymphs offer signals that a new host is large enough to house a colony of mites. When a host cockroach dies, the mites wander aimlessly on the carcass until they die, too."

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.

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.

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

Moxie, the African lion cub in this picture, made her public debut at the Bronx Zoo in New York yesterday.

"An adult male named M'wasi and young adult female, Sukari, were introduced to each other in 2008 as part of a cooperative zoo breeding effort," said a news statement by the Wildlife Conservation Society, the conservation charity that manages the zoo. "After the courtship, Moxie was born on November 6, 2008, weighing about 3 pounds at birth. Moxie could grow to be 350 pounds as an adult."

WCS photo by Julie Larsen Maher

"We have waited a long time for this birth," said Jim Breheny, WCS Director of the Bronx Zoo, in the statement. "She is definitely a scene-stealer with a spunky and playful personality. We are pleased to debut her on Earth Day. We are certain that Bronx Zoo-goers who are coming out for our WCS Run for the Wild this Saturday and the last weekend of our Earth Month celebration will enjoy seeing our new cub."

Lions live in grasslands and open woodlands across much of sub-Sahara Africa. Their Lion Island home at the Bronx Zoo's African Plains depicts this habitat. "This popular exhibit opened in 1941 to record crowds and is still an emblematic home for this icon species," WCS said. The exhibit showcases African wildlife in a predator-prey setting with a moat separating them.

WCS photo by Julie Larsen Maher

Across Africa, lions and other great predators are disappearing, according to WCS. "Until recently scientists believed there were 100,000-200,000 lions living in Africa, but a recent survey has found that the number has dropped dramatically to approximately 29,000 (IUCN 2006,) and most of these are living in protected national parks and reserves.

"Outside of these protected areas lions are being slaughtered at an alarming rate by people who kill them to protect their livestock," WCS added. "Ever-expanding human populations push people and livestock into the remaining lion range, causing habitat destruction and bushmeat poaching, which decimates wild prey and forces lions to depend on livestock for food. Unless urgent action is taken, lions may be completely wiped out from these unprotected areas."

The study, led by scientists at the National Center for Atmospheric Research (NCAR), suggests that in many cases the reduced flows are associated with climate change, NCAR said in a news release. "The process could potentially threaten future supplies of food and water."

NGS photo of Ganges River by George F. Mobley

"Reduced runoff is increasing the pressure on freshwater resources in much of the world, especially with more demand for water as population increases," says NCAR scientist Aiguo Dai, the lead author, in the release. "Freshwater being a vital resource, the downward trends are a great concern."

"The study raises wider ecological and climate concerns. Discharge from the world's great rivers results in deposits of dissolved nutrients and minerals into the oceans.

UCAR photo of Aiguo Dai by Carlye Calvin

"The freshwater flow also affects global ocean circulation patterns, which are driven by changes in salinity and temperature and which play a vital role in regulating the world's climate."

"On January 17, 1971, I witnessed a crude oil spill of nearly a half-million gallons in the waters near the Golden Gate Bridge," he writes in his book "Planetwalker."

"The oil spill was my first experience with a major environmental insult.

"As I drove my car over the Golden Gate I felt some responsibility for the mess washing up on the shore. It was nearly a year afterwards, still feeling this responsibility, that I gave up the use of motorized vehicles and started walking."

Months after he started walking everywhere, Francis took a vow of silence to demonstrate his conviction. For the next two decades he walked ... and walked.

First he hiked across America from the Pacific to the Atlantic, then across Cuba and Brazil. "Planetwalker," (National Geographic Books, $16.95), released today in softcover, describes the experience of his silent crusade, how it expanded into a quest to improve how humans treat each other, and how people can better communicate and work together to benefit the planet.

"I had begun a pilgrimage, an outer and inner journey, as part of my education dedicated to raise environmental consciousness, promote earth stewardship and world peace," Francis writes.

The Importance of Listening

Walking in silence, Francis says, he learned the importance of listening. He ended his silence on Earth Day 1990, but not his pilgrimage.

I spoke to Francis on the phone earlier today. He is in the middle of retracing his epic walk around the United States, but in the reverse direction. "On this walk I can speak to people," he told me. "I am retracing my steps to see what is different from my first journey--and to form a partnership with people and organizations on environmental issues."

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.

Biologists have discovered that amphibian diseases are spread by bait shops.

National Science Foundation illustration by Nicolle Rager-Fuller

Salamander larvae sold as live bait for freshwater fishing may be spreading amphibian diseases, including the chytrid fungus that is killing many of the world's frogs, the National Science Foundation says.

Waterdogs, as the larvae of tiger salamanders are called, are used to catch largemouth bass, channel catfish and other freshwater fishes.

Fishers may be in for more than they bargained for, the NSF said in a statement released yesterday. "Salamanders in bait shops in Arizona, Colorado and New Mexico are infected with ranaviruses, and those in Arizona, with a chytrid fungus called Batrachochytrium dendrobatidis (Bd)."

These diseases have spread with the global trade in amphibians, says James Collins, assistant director for biological sciences at the NSF. Collins is currently on leave from Arizona State University. "The commercial amphibian bait trade may be a source of 'pathogen pollution,'" he says in the NSF news release. Pathogens are disease-causing agents such as some viruses and bacteria.

The scientists also organized bait-shop surveys to determine whether tiger salamanders are released back into the wild after being housed in shops, the NSF says.

A majority of anglers--as high as 73 percent--in Arizona, Colorado, and New Mexico uses waterdogs as bait.

Photo by Angela Picco, ASU

"We found that all tiger salamanders that ended up in the bait trade were originally collected from the wild," says Picco. "In general, they were moved from east to west and north to south--bringing with them multiple ranavirus strains."

Results of the research show that 26 to 73 percent of fishers used tiger salamanders as bait; 26 to 67 percent of anglers released tiger salamanders bought as bait into fishing waters; and 4 percent of bait shops put salamanders back in the wild after the waterdogs were housed with infected animals.

"The tiger salamander bait trade in the western U.S. is a good model for understanding the consequences of unregulated movement of amphibians and their pathogens," says Collins.

Examples of pathogen pollution are many and dramatic, the NSF statement says.

Dr. Zahi Hawass, the Secretary General of Egypt's Supreme Council of Antiquities (SCA) and a National Geographic Explorer-in-Residence, believes this is about to change.

Hawass, and his all-Egyptian team of archaeologists are working in three different areas in the storied Valley of the Kings: between the tombs of Merenptah and Ramses II on the northern side of the central valley; in the area to the south of the tomb of Tutankhamun; and in the Western Valley, where the tombs of Amenhotep III and Ay are located.

Each of these excavations has revealed important information, the Supreme Council of Antiquities says in a news release.

NGS photo of Zahi Hawass by David Braun

"The team has recently made many important and exciting discoveries, which are revolutionizing our understanding of one of the most mysterious and fascinating places in Egypt," Hawass says in the release. "There are still a number of kings and other royals who were probably buried in the Valley of the Kings, but whose tombs have not yet been found.

"The resting places of Ramses VIII, Thutmose II, and the queens and princes of the 18th Dynasty are still unknown. There are still many treasures left to be discovered in the valley," Hawass says.

The Valley of the Kings is one of the richest and most fascinating archaeological sites in the world. It was here that in 1922, Howard Carter found the tomb and treasures of Tutankhamun (the tomb known to archaeologists as KV62), perhaps the most sensational discovery in the history of archaeology.

NGS photo of the Valley of the Kings by David Braun 

Photo by Adrian Gonsalves

Palm Sunday crosses may be contributing to the destruction of rainforest ecosystems throughout Central America, in particular in Belize," Fauna & Flora International (FFI) said in a statement last night.

Xaté is a type of palm that is commonly used in flower arrangements across the U.S. and other countries, said Rebecca Foges, communications officer for the UK-based conservation charity, in an email to the media. "Church flower arrangements on Palm Sunday make up as much as 15 percent of global demand for this leaf."

Xaté (pronounced sha-tay) is a term that covers several types of small palm species in the Chamaedorea genus which live across Central and South America, according to an FFI fact sheet. Xaté palm leaves are used as a "green background" or filler in floral arrangements.

Chamaedorea ernesti-augustii or "fishtail" (so-named because of its split leaves) is one of the species of palm which is most harvested by Xatéros (xaté harvesters) in Belize.

Photo courtesy Ya'axché Conservation Trust

Wild xaté is currently overharvested across its range (Mexico, Guatemala, and Belize and other Central American countries), which is directly threatening the stability and security of its rainforest ecosystem, Foges said.

Fauna & Flora International and its Belizean partner NGO, the Ya'axché Conservation Trust, have been working to reduce the pressure illegal Xateros (xaté harvesters) are having on Belize's natural parks to ensure a future in the wild for the slow-growing palm, Foges added.

"In fact, Ya'axché was involved in a serious incident only last week in which 16 Xateros were arrested in Belize's most important nature reserve."

Ya'axché reports on its blog that a joint effort with Belizean authorities last month apprehended 16 Guatemalan Xatéros allegedly harvesting xaté illegally within Belize's Bladen Nature Reserve (BNR) and Cockscomb Basin Wildlife Sanctuary. Freshly cut xaté was confiscated.

More than 18,000 stems of xaté were confiscated and destroyed by rangers in Belize last month.

Photo courtesy Ya'axché Conservation Trust

Ya'axché rangers were tipped off to the Xatéros' presence when they approached the BNR Ranger Base and presented a license to harvest from the Belize Forest Department, the blog reports. "After being informed that no xaté extraction of any kind is allowed in BNR, the Xatéros left, but a routine ranger patrol [found] signs of significant xaté removal. Several square miles within BNR had been stripped of xaté, as well as several visible hills in the Cockscomb Basin Wildlife Sanctuary."

Patrols were dispatched and Xateros were found with a cache of 26 bales of xaté, the blog says. Each bale held 70 bundles and each bundle held 40 leaves, representing over 18,000 plants harvested.

None of the people detained carried a passport nor any kind of Belizean work permit or visa, the blog added. "The plants that were cut were not cut in a sustainable manner either. For a xaté plant to live, no more than one of its mature leaves may be removed. Inspecting rangers spotted nearly every harvested plant to have been stripped of all of their leaves, many of them completely removed from their rooted stem."

A typical excuse, and the one offered by the detained group, the blog adds, is that the Xatéros mean to harvest legally but do not know the boundaries between where they are allowed to harvest and where they are not. "The same happens in the illegal logging industry. We would like to see greater support from the Forest Department, and the government of Belize, in enforcing these boundaries," the blog says. "Additionally, monitoring the validity of harvest permits and the adherence to the rules set within them must be strengthened."