No single origin for agriculture in the Fertile Crescent

Transition from foraging to farming occurred over the entire Fertile Crescent

A rich assemblage of fossils and artifacts in the foothills of the Zagros Mountains in Iran has revealed that the early inhabitants of the region began cultivating cereal grains for agriculture between 12,000 and 9,800 years ago. The discovery implies that the transition from foraging to farming took place at roughly the same time across the entire Fertile Crescent, not in a single core area of the "cradle of civilization," as previously thought.

Until recently, political pressures had limited excavations of archaeological sites in the eastern Fertile Crescent, or modern-day Iran, while findings to the west—at sites in Cyprus, Syria, Turkey and Iraq, for example—provided detailed clues to the origins of agriculture.

Now, Simone Riehl from the University of Tübingen in Germany, along with colleagues from the Tübingen Senckenberg Center for Human Evolution and Paleoecology, have analyzed plant remains at the aceramic (pre-pottery) Neolithic site of Chogha Golan in Iran, and their results show that people were growing and grinding cereal grains like wheat and barley at the same time as their counterparts to the west.

Their findings appear in the 5 July issue of the journal Science.

"During the last few decades, numerous archaeological excavations were conducted in the Near East that led researchers to consider the possibility that multiple regions in the Fertile Crescent began cultivating cereal grains roughly at the same time, rather than just a single core area," Riehl explained.

The plant remains found at the Chogha Golan site document more than 2,000 years of the region's land use and represent the earliest record of long-term plant management in Iran, according to the researchers. The site's excavation, which was conducted by archaeologists from the University of Tübingen and the Iranian Center for Archaeological Research between 2009 and 2010, shows that Chogha Golan's early inhabitants cultivated wild barley, wheat, lentil and grass peas—and eventually domesticated emmer wheat—during their occupation, which began about 12,000 years ago.

"Plentiful findings of chaff remains of the cereals indicate that people processed their harvest within the sites they were living in," Riehl said. "Mortars and grinding stones may have been used for turning the grain into some kind of bulgur or flour, which may have been further processed either by cooking or roasting." (The author also notes, however, that chemical studies of the grinding tools showed that they were multi-purpose—not just for processing plant materials.)

Taken together, these new insights suggest that the eastern region of the Fertile Crescent likewise made significant contributions to the development of Neolithic culture. The findings by Riehl et al. indicate that essentially simultaneous processes led to the management of wild plants and the domestication of cereal grains across most of the Fertile Crescent.

But, how such strategies were disseminated over the entire Fertile Crescent—whether by the communication of ideas, the spread of crops or the migration of people—remains to be seen, according to the researchers.

"For some time, the emergence of agriculture in Iran was considered as part of a cultural transfer from the west," Riehl said. "This opinion was, however, mostly based on the lack of information from Iranian sites."

"We meanwhile assume that key areas for emerging domestication existed over the whole Fertile Crescent, and that there were several locations where domesticated species evolved as a result of cultivation by local human groups," the author concluded. "This does not, of course, exclude the possibility of some kind of transfer of ideas and materials between the different groups populating the Fertile Crescent."
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References:

EurekAlert. 2013. “No single origin for agriculture in the Fertile Crescent”. EurekAlert. Posted: July 4, 2013. Available online: http://www.eurekalert.org/pub_releases/2013-07/aaft-ns062813.php

4000-year-old banana roots in Southeast Asia

Scientists have plucked clues from genetics, archaeology and linguistics to reconstruct a history of the domestication of bananas, showing that some of India's cultivated bananas have 4,000-year old genomic roots from Southeast Asia.

Their studies suggest that the earliest cultivation of bananas was in the Kuk Swamp area of Papua New Guinea about 6,600 years ago, and that bananas were ferried by small groups of people from Southeast Asia moving westward into India and beyond.

A Southeast Asian banana species known as Mlali, a short and yellow variety, was carried from the Indonesian islands into India around 4,000 years ago where its genome is still found in three varieties ' Pome, Nendra Padithi and Nadaan, their studies show.

The findings appeared this month in the Proceedings of the National Academy of Sciences.

"It probably arrived 4,000 years ago, give or take a few hundred years. We don't have enough archaeological data to narrow things down," said Mark Donohue, a linguist at the Australian National University who was involved in the study.

The researchers combined genetic, archaeological and linguistic information to trace the domestication of the Musa family of bananas, which includes the standard yellow bananas sold around the world. The researchers assumed that any cultivated plant would travel with people along with its name, and when a plant is culturally new, its name would be retained in the places where it had been introduced.

Linguistic data supports the long route of dispersal from Indonesia to India.

Many present-day words for bananas appear to root from the word qarutay that researchers believe had its origins in the Philippines. As the bananas moved, so did their names, slightly tweaked at each new land where it was absorbed.

"Agutay, arutay, kelutay, kalu and the Hindi term kela are all derived from qarutay," said Xavier Perrier, a systems biologist and research team member at the Centre for Agricultural Research and Development in Montpellier, France. "The word travelled from the Philippines across Vietnam, Thailand and Burma into India," Perrier told The Telegraph. "This is exactly the route that the Mlali variety took into India," he said.

"This study confirms that the Indo-China region was the centre of origin of bananas," said M. Mohamed Mustaffa, the director of India's National Research Centre for Banana, Tiruchirapalli, who was not associated with the study.

"India has wild bananas native to the northeastern region and some in the Western Ghats, but the bananas cultivated today are products of the crossing of species with part of the genomic makeup coming from Southeast Asian varieties," Mustaffa said.

Archaeology also supports the westward flow of bananas into South Asia from Southeast Asian islands. Residues of Musa dating back to about 4,000 years have been observed at a site named Kot Diji in Pakistan.

Donohue said the studies also provided clear evidence for movement of people from the east to the west. "We know that the inhabitants of Madagascar are at least in part the descendants of an east-to-west movement about 1,200 years ago," Donohue told The Telegraph.

"We also have some records of people from Java and Malaysia trading with India about 2,000 years ago," he said. "It could have been a minor movement in terms of the number of people, but a big transformation in terms of culture."

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References:

Mudur, G.S. 2011. "4000-year-old banana roots in Southeast Asia". Yahoo News. Posted: July 17, 2011. Available online: http://in.news.yahoo.com/4000-old-banana-roots-southeast-asia-000000938.html

Deep History of Coconuts Decoded: Origins of Cultivation, Ancient Trade Routes, and Colonization of the Americas

he coconut (the fruit of the palm Cocos nucifera) is the Swiss Army knife of the plant kingdom; in one neat package it provides a high-calorie food, potable water, fiber that can be spun into rope, and a hard shell that can be turned into charcoal. What's more, until it is needed for some other purpose it serves as a handy flotation device.



No wonder people from ancient Austronesians to Captain Bligh pitched a few coconuts aboard before setting sail. (The mutiny of the Bounty is supposed to have been triggered by Bligh's harsh punishment of the theft of coconuts from the ship's store.)

So extensively is the history of the coconut interwoven with the history of people traveling that Kenneth Olsen, a plant evolutionary biologist, didn't expect to find much geographical structure to coconut genetics when he and his colleagues set out to examine the DNA of more than 1300 coconuts from all over the world.

"I thought it would be mostly a mish-mash," he says, thoroughly homogenized by humans schlepping coconuts with them on their travels.

He was in for a surprise. It turned out that there are two clearly differentiated populations of coconuts, a finding that strongly suggests the coconut was brought under cultivation in two separate locations, one in the Pacific basin and the other in the Indian Ocean basin. What's more, coconut genetics also preserve a record of prehistoric trade routes and of the colonization of the Americas.

The discoveries of the team, which included Bee Gunn, now of the Australian National University in Australia, and Luc Baudouin of the Centre International de Recherches en Agronomie pour le Développement (CIRAD) in Montpellier, France, as well as Olsen, associate professor of biology at Washington University in St. Louis, are described in the June 23 online issue of the journal PLoS ONE.

Morphology a red herring

Before the DNA era, biologists recognized a domesticated plant by its morphology. In the case of grains, for example, one of the most important traits in domestication is the loss of shattering, or the tendency of seeds to break off the central grain stalk once mature.

The trouble was it was hard to translate coconut morphology into a plausible evolutionary history.

There are two distinctively different forms of the coconut fruit, known as niu kafa and niu vai, Samoan names for traditional Polynesian varieties. The niu kafa form is triangular and oblong with a large fibrous husk. The niu vai form is rounded and contains abundant sweet coconut "water" when unripe.

"Quite often the niu vai fruit are brightly colored when they're unripe, either bright green, or bright yellow. Sometimes they're a beautiful gold with reddish tones," says Olsen.

Coconuts have also been traditionally classified into tall and dwarf varieties based on the tree "habit," or shape. Most coconuts are talls, but there are also dwarfs that are only several feet tall when they begin reproducing. The dwarfs account for only 5 percent of coconuts.

Dwarfs tend to be used for "eating fresh," and the tall forms for coconut oil and for fiber.

"Almost all the dwarfs are self fertilizing and those three traits -- being dwarf, having the rounded sweet fruit, and being self-pollinating -- are thought to be the definitive domestication traits," says Olsen.

"The traditional argument was that the niu kafa form was the wild, ancestral form that didn't reflect human selection, in part because it was better adapted to ocean dispersal," says Olsen. Dwarf trees with niu vai fruits were thought to be the domesticated form.

The trouble is it's messier than that. "You almost always find coconuts near human habitations," says Olsen, and "while the niu vai is an obvious domestication form, the niu kafa form is also heavily exploited for copra (the dried meat ground and pressed to make oil) and coir (fiber woven into rope)."

"The lack of universal domestication traits together with the long history of human interaction with coconuts, made it difficult to trace the coconut's cultivation origins strictly by morphology," Olsen says.

DNA was a different story.

Collecting coconut DNA

The project got started when Gunn, who had long been interested in palm evolution, and who was then at the Missouri Botanical Garden, contacted Olsen, who had the laboratory facilities needed to study palm DNA.

Together they won a National Geographic Society grant that allowed Gunn to collect coconut DNA in regions of the western Indian Ocean for which there were no data. The snippets of leaf tissue from the center of the coconut tree's crown she sent home in zip-lock bags to be analyzed.

"We had reason to suspect that coconuts from these regions -- especially Madagascar and the Comoros Islands -- might show evidence of ancient 'gene flow' events brought about by ancient Austronesians setting up migration routes and trade routes across the southern Indian Ocean," Olsen says.

Olsen's lab genotyped 10 microsatellite regions in each palm sample. Microsatellites are regions of stuttering DNA where the same few nucleotide units are repeated many times. Mutations pop up and persist pretty easily in these regions because they usually don't affect traits that are important to survival and so aren't selected against, says Olsen. "So we can use these genetic markers to 'fingerprint' the coconut," he says.

The new collections were combined with a vast dataset that had been established by CIRAD, a French agricultural research center, using the same genetic markers. "These data were being used for things like breeding, but no one had gone through and systematically examined the genetic variation in the context of the history of the plant," Olsen says.

Two origins of cultivation

The most striking finding of the new DNA analysis is that the Pacific and Indian Ocean coconuts are quite distinct genetically. "About a third of the total genetic diversity can be partitioned between two groups that correspond to the Indian Ocean and the Pacific Ocean," says Olsen.

"That's a very high level of differentiation within a single species and provides pretty conclusive evidence that there were two origins of cultivation of the coconut," he says.

In the Pacific, coconuts were likely first cultivated in island Southeast Asia, meaning the Philippines, Malaysia, Indonesia, and perhaps the continent as well. In the Indian Ocean the likely center of cultivation was the southern periphery of India, including Sri Lanka, the Maldives, and the Laccadives.

The definitive domestication traits -- the dwarf habit, self-pollination and niu vai fruits -- arose only in the Pacific, however, and then only in a small subset of Pacific coconuts, which is why Olsen speaks of origins of cultivation rather than of domestication.

"At least we have it easier than scientists who study animal domestication," he says. "So much of being a domesticated animal is being tame, and behavioral traits aren't preserved in the archeological record."

Did it float or was it carried?

One exception to the general Pacific/Indian Ocean split is the western Indian Ocean, specifically Madagascar and the Comoros Islands, where Gunn had collected. The coconuts there are a genetic mixture of the Indian Ocean type and the Pacific type.

Olsen and his colleagues believe the Pacific coconuts were introduced to the Indian Ocean a couple of thousand years ago by ancient Austronesians establishing trade routes connecting Southeast Asia to Madagascar and coastal east Africa.

Olsen points out that no genetic admixture is found in the more northerly Seychelles, which fall outside the trade route. He adds that a recent study of rice varieties found in Madagascar shows there is a similar mixing of the japonica and indica rice varieties from Southeast Asia and India.

To add to the historical shiver, the descendants of the people who brought the coconuts and rice are still living in Madagascar. The present-day inhabitants of the Madagascar highlands are descendants of the ancient Austronesians, Olsen says.

Much later the Indian Ocean coconut was transported to the New World by Europeans. The Portuguese carried coconuts from the Indian Ocean to the West Coast of Africa, Olsen says, and the plantations established there were a source of material that made it into the Caribbean and also to coastal Brazil.

So the coconuts that you find today in Florida are largely the Indian ocean type, Olsen says, which is why they tend to have the niu kafa form.

On the Pacific side of the New World tropics, however, the coconuts are Pacific Ocean coconuts. Some appear to have been transported there in pre-Columbian times by ancient Austronesians moving east rather than west.

During the colonial period, the Spanish brought coconuts to the Pacific coast of Mexico from the Philippines, which was for a time governed on behalf of the King of Spain from Mexico.

This is why, Olsen says, you find Pacific type coconuts on the Pacific coast of Central America and Indian type coconuts on the Atlantic coast.

"The big surprise was that there was so much genetic differentiation clearly correlated with geography, even though humans have been moving coconut around for so long."

Far from being a mish-mash, coconut DNA preserves a record of human cultivation, voyages of exploration, trade and colonization.
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References:

2011. "Deep History of Coconuts Decoded: Origins of Cultivation, Ancient Trade Routes, and Colonization of the Americas". Science Daily. Posted: June 24, 2011. Available online: http://www.sciencedaily.com/releases/2011/06/110624142037.htm