East African grasslands influenced human evolution

Grasslands dominated the cradle of humanity in east Africa longer and more broadly than thought, says a study published Thursday, bolstering the idea that the rise of such landscapes shaped human evolution.

According to the so-called "savannah hypothesis", the gradual transition from dense forests into grasslands helped drive the shift toward bipedalism, increased brain size and other distinctively human traits.

First outlined in the 1920s, the theory suggests that our most ancient upright ancestors learned to walk on two feet, in part, to peer over tall grass in search of prey and predators.

Rather than simply plucking fruit from trees, they had to become shrewd hunters and move longer distances in order to survive.

The notion has been debated for more than a century, however, with some scientists saying other forces were more important in driving humans to assume their signature posture.

They also point to studies showing that the landscapes of the two regions of east Africa richest in hominid fossils -- the Awash Valley and The Omo-Turkana Basin, both in Ethiopia -- were in fact quite diverse in terms of tree cover.

One of the most complete early hominin species yet discovered, Ardipithecus ramidus, for example, may have lived primarily inside woodlands and patches of forest, they argue.

Hominins include early humans and pre-humans, along with the early ancestors of chimpanzees andgorillas.

The new study, published in Nature, will not settle the debate, but it offers evidence that savannahs -- with their limited tree cover -- stretched back even beyond the five million-year boundary widely assumed up to now, especially in areas populated by our distant forebear.

"There have been open habitats for all of the last six million years in the environments in eastern Africa where some of the most significant early human fossils were found," said Thure Cerling, a professor at the University of Utah and lead researcher of the study.

"Wherever we find human ancestors, we find evidence for open habitats similar to savannahs -- much more open and savannah-like than forested," he said in a statement.

Combining an analysis of soil samples and satellite photos of tropical regions around the world, the researchers created vegetation chronologies for the regions home to many hominin fossils, including Ardipithecus, Australopithecus, Paranthropus and our own genus, Homo.

During the past 7.4 million years woody cover has ranged from 75 to five percent, they found.

But significant areas of savannah -- below 40 percent wood cover -- were consistently present "all the time for which we have hominin fossils in the environments where the fossils were found during the past 4.3 millions years," thus including the oldest human ancestors, Cerling said.

Up to now, many scientists believe that East Africa was forested up until two million years ago, he added.

"This study shows that during the development of bipedalism -- about four million years ago -- open conditions were present and even predominant," Cerling said.

Early humans began in southern Africa, study suggests

Modern humans may have originated from southern Africa, an extensive genetic study has suggested.

Data showed that hunter-gatherer populations in the region had the greatest degree of genetic diversity, which is an indicator of longevity.

It says that the region was probably the best location for the origin of modern humans, challenging the view that we came from eastern Africa.

"Africa is inferred to be the continent of origin for all modern human populations," the international team of researchers wrote.

"But the details of human prehistory and evolution in Africa remain largely obscure owing to the complex histories of hundreds of distinct populations."

Co-author Brenna Henn, from Stanford University, California, said the team's study - the most comprehensive of its kind - reached two main conclusions.

"One is that there is an enormous amount of diversity in African hunter-gatherer populations, even more diversity than there is in agriculturalist populations," she told BBC News.

"These hunter/gatherer groups are highly structured and are fairly isolated from one another and probably retain a great deal of different genetic variations - we found this very exciting."

Dr Henn added: "The other main conclusion was that we looked at patterns of genetic diversity among 27 (present-day) African populations, and we saw a decline of diversity that really starts in southern Africa and progresses as you move to northern Africa."

She explained that the team's modelling was consistent with the serial founder effect. This refers to a loss of genetic variation when a new population is established by a very small number of individuals from the original, larger population.

"Populations in southern Africa have the highest genetic diversity of any population, as far as we can tell.

"So this suggests that this might be the best location for (the origins) of modern humans."

Chris Stringer, a leading palaeontologist based at the Natural History Museum, London, said: "The new paper... suggests that the genes of the Namibian and Khomani bushmen (southern Africa), Biaka pygmies (Central Africa) and the Sandawe (East Africa) appear to be the most diverse, and by implication these are the most ancient populations of Homo sapiens."

Professor Stringer, who was not involved in the study, added: "This is a landmark study, with far more extensive data on... hunter gatherer groups than we have ever had before, but I am cautious about localising origins from it."

He said that the ranges of these groups were currently quite limited, but rock paintings by ancient populations that had been linked to the Bushman hinted that they were once far more widespread.

"It seems more likely that the surviving hunter-gatherer groups are now localised remnants of populations that formerly ranged across much of sub-Saharan Africa 60,000 years ago," he told BBC News.

Professor Stringer said that he no longer thought that there was a single "Garden of Eden" where we evolved. Instead, he said, "distinct populations in ancient Africa probably contributed to the genes and behaviours that make up modern humans".

From BBC

Check out the full article at the PNAS website

About the Header

This header comes from a photograph taken in Kenya in 2007. During the summer months I worked in the Southern Kenya Great Rift Valley at a variety of early human occupation sites.  A full publication of the work can be found in Issue #71 of Nyame Akuma, The Journal of the Society of Africanist Archaeologists.

The treasures of Timbuktu: Preserving Africa's rich cultural heritage

A drizzle of dust and sand falls over Ahmed Saloum Boularaf's fingers as he gently lifts the ancient, camel-skin bound manuscripts from a wooden box and puts them on a desk in his makeshift library in a mud-brick house close to the centre of Timbuktu.

"Termites, rain and mice," he said in an accusing voice, brushing a few flecks of 15th Century parchment from his jacket.

"This was my grandfather's collection. It covers topics from science to medicine, history, theology, grammar, geography - a little of everything."

Across Timbuktu, in cupboards, rusting chests, private collections and libraries, tens or perhaps hundreds of thousands of manuscripts bear witness to this legendary city's remarkable intellectual history, and by extension, to Africa's much overlooked pre-colonial heritage.

"This is the proof," said Mr Boularaf.

"Africa was not wild before the white man came. In fact, if you will excuse the expression, it was the colonising that was wild."

But this unique literary evidence is under threat, as time, the elements, and a simple lack of resources take their toll in northern Mali.
"We are losing manuscripts every day. We lack the financial means to catalogue and protect them," said Mr Boularaf, who recently rescued his collection from the rubble of a mud building next door that collapsed after a rainstorm.

Now a giant, new, state of the art library has landed - rather like a spaceship - in the dilapidated centre of Timbuktu, offering the best hope of preserving and analysing the town's literary treasures.

After several years of building and delays, the doors are finally about to open at the Ahmed Baba Institute's new home - a 200 million rand (£16,428,265) project paid for by the South African government.

"It's a dream come true," said South African curator Alexio Motsi, exploring the underground, climate-controlled storage rooms that will soon house some 30,000 manuscripts.

On the ground floor, behind elegant colonnades and fountains, rows of empty desks are ready for newly trained workers to begin repairing and digitizing the documents.

"I feel proud… and nervous," Mr. Motsi said as his team prepared to hand over the keys of the institute to the Malian authorities.

The struggle to save Timbuktu's manuscripts has been gaining momentum for many years.

When South Africa's former President, Thabo Mbeki, visited the town in 2001 he declared the documents to be among the continent's "most important cultural treasures", and promised to help conserve them as part of his vision of an "African renaissance".

Most of the manuscripts are in Arabic script, but contain many local languages.

They provide unique insights into Timbuktu's emergence as a trading post, and by the 1500s as a famous university town, full of students and scribes.

They also help refute the notion that sub-Saharan Africa produced only oral histories, with little or no written records.

Some of the documents discuss social and political problems, usually in an Islamic context, while others offer medicinal advice, including one 13th Century herbal remedy to help treat women in labour.

"I think pre-colonial Africa had its own civilisation going on, which matches what was going on in the west," said Mr Motsi.

"There's a lot to be uncovered here. It's time we started relooking at the history we were taught in school about Africa."

The new institute plans to hold exhibitions, and open a souvenir and coffee shop in order to translate interest in the manuscripts into tourist revenue for one of the world's poorest countries.

But those ambitions will not have been helped by new travel advisories issued by the UK and US governments, which are warning tourists to steer clear of the town altogether because of the threat of kidnapping by militants with links to al-Qaeda, who are now using the Sahara as a hiding place.

From BBC.co.uk
Head over to the BBC to watch an exclusive video report of this story.

Malawi: Cradle of humankind?

KARONGA, Malawi (Reuters) – The latest discovery of pre-historic tools and remains of hominids in Malawi's remote northern district of Karonga provides further proof that the area could be the cradle of humankind, a leading German researcher said.

Professor Friedemann Schrenk of the Goethe University in Frankfurt told Reuters that two students working on the excavation site last month had discovered prehistoric tools and a tooth of an hominid.

"This latest discovery of prehistoric tools and remains of hominids provides additional proof to the theory that the Great Rift Valley of Africa and perhaps the excavation site near Karonga can be considered the cradle of humankind," Schrenk said.

A hominid is a member of a family of primates which includes humans and their prehistoric ancestors.

The discovery was at Malema excavation site, 10 km (6 miles) from Karonga.

The site also contains some of the earliest dinosaurs which lived between 100 million and 140 million years ago and early hominids believed to have lived between a million and 6 million years ago.

He is leading a team of researchers from Europe and Africa to establish an African center for interdisciplinary studies on mammal and hominid evolution in the southern African nation.

Karonga is about 615 km (380 miles) north of the capital Lilongwe and is near the border with Tanzania.

(Editing by Gugulakhe Lourie)