Feeds:
Posts
Comments

Posts Tagged ‘wild grasses’

Agricultural decisions made by our ancestors more than 10,000 years ago could hold the key to food security in the future, according to new research by the University of Sheffield.

Scientists, looking at why the first arable farmers chose to domesticate some cereal crops and not others, studied those that originated in the Fertile Crescent, an arc of land in western Asia from the Mediterranean Sea to the Persian Gulf.

They grew wild versions of what are now staple foods like wheat and barley along with other grasses from the region to identify the traits that make some plants suitable for agriculture, including how much edible seed the grasses produced and their architecture.

Dr Catherine Preece, who worked on the study with colleagues from the University’s Department of Animal and Plant Sciences and Department of Archaeology, said: “Our results surprised us because numerous other grasses that our ancestors ate, but we do not, can produce just as much seed as wild wheat and barley. It is only when these plants are grown at high densities, similar to what we would find in fields, that the advantage of wild wheat and barley is revealed.”

The study identified two key characteristics shared by the wild relatives of current crop plants. Firstly they have bigger seeds, which means they grow into bigger seedlings and are able to get more than their fair share of light and nutrients, and secondly, as adult plants they are less bushy than other grasses and package their big seeds onto fewer stems. This means crop wild relatives perform better than the other wild grasses that they are competing with and are better at growing close together in fields, making them ideal for using in agriculture.

“The results are important because our expanding human population is putting increasing demands on food production,” said Dr Preece.

“Before humans learnt how to farm, our ancestors ate a much wider variety of grasses. If we can understand what traits have made some grasses into good crops then we can look for those characteristics in other plants and perhaps identify good candidates for future domestication.”

She added: “To shape the future we must understand the past, so the more we can discover about the origins of agriculture, the more information we will have to help us tackle the challenges that face modern day food production.”

So far the researchers have been conducting their experiments in greenhouses and their results indicate that the traits affecting how plants compete with each other are crucial factors to determining the success of a crop.

The team now plan to observe how the plants interact in their natural environment by growing them in experimental fields in Turkey, the heart of the Fertile Crescent. They hope that their experiments will yield another crop of important results.

“Cereal breeders are taking an increasing interest in modern crops’ wild relatives as a source of useful traits that may help to increase yields or increase resilience to climate change, and our work should help in this process,” said Dr Preece.

Dr Preece presented the results of this study to the joint British Ecological Society and the French Ecological Society today (Thursday 11 December 2014) in the Grand Palais, Lille.

2015/01/img_1469.jpg

Original article:
sheffield.ac.uk

Read Full Post »

20131115-115613.jpg

Huts used for storing fodder dot the floodplains, where sedges have been harvested for hundreds of years without additional fertilization. Early settlers cleared willows to encourage and harvest sedges and grasses. Credit: T DeLuca/U of Washington

Topic: Early Agriculture in the North

Floods didn’t make floodplains fertile during the dawn of human agriculture in the Earth’s far north because the waters were virtually devoid of nitrogen, unlike other areas of the globe scientists have studied.

Instead, the hardy Norsemen and early inhabitants of Russia and Canada have microorganisms called cyanobacteria to mostly thank for abundant grasses that attracted game to hunt and then provided fodder once cattle were domesticated. The process is still underway in the region’s pristine floodplains.

The new findings are surprising because it’s long been assumed that nitrogen crucial to plant growth mainly arrived with floods of river water each spring, according to Thomas DeLuca, a University of Washington professor of environmental and forest sciences and lead author of a paper in the Nov. 6, 2013 issue of the journal PLOS ONE.

Discovering that cyanobacteria in the floodplains were responsible for nitrogen fixation – that is taking it from the atmosphere and “fixing” it into a form plants can use – partially resolves the scientific debate of how humans harvested grasses there for hundreds of years without fertilizing, DeLuca said. It raises the question of whether farmers today might reduce fertilizer use by taking advantage of cyanobacteria that occur, not just in the floodplains studied, but in soils around the world, he said.

It also might lead to more accurate models of nitrogen in river systems because none of the prominent models consider nitrogen being fixed in floodplains, DeLuca said. Scientists model nitrogen loading of rivers, especially where industrial fertilizers and effluent from wastewater-treatment plants cause dead zones and other problems in the lower reaches and mouths of rivers.

Ten rivers and 71 flood plains were studied in northern Fennoscandia, a region that includes parts of Scandinavia and Finland. The rivers were chosen because their upper reaches are pristine, haven’t been dammed and are not subject to sources of human-caused nitrogen enrichment – much like river systems humans encountered there hundreds of years ago, as agriculture emerged in such “boreal” habitats. Boreal habitat – found at 60 degrees latitude and north all the way into the Arctic Circle, where it meets tundra habitat – is the second largest biome or habitat type on Earth.

In the northern regions of the boreal, the surrounding hillsides have thin, infertile soils and lack shrubs or herbs that can fix nitrogen. In these uplands, feather mosses create a microhabitat for cyanobacteria, which fix a modest amount of nitrogen that mostly stays on site in soils, trees and shrubs. Little of it reaches waterways. On the floodplains, high rates of nitrogen fixation occur in thick slimy black mats of cyanobacteria growing in seasonably submerged sediments and coating the exposed roots and stems of willows and sedges.

“We joke and call the floodplains the ‘mangroves of the North’ because there are almost impenetrable tangles of willow tree roots in places, like a micro version of the tropical and subtropical mangroves that are known to harbor highly active colonies of cyanobacteria,” DeLuca said.

“It turns out there’s a lot of nitrogen fixation going on in both,” he said. For example, the scientists discovered that in spite of the dark, cold, snowy winters of Northern Sweden, the cyanobacteria there fix nitrogen at rates similar to those living the life in the toasty, sun-warmed Florida Everglades.

The amount of nitrogen provided by the cyanobacteria to unharvested willows and sedges is perhaps a quarter of what U.S. farmers in the Midwest apply in industrial fertilizers to grain crops and as little as a sixth of what they apply to corn.

Human-made fertilizers can be fuel-intensive to produce and use, for example, it takes the energy of about a gallon of diesel to produce 4 pounds of nitrogen fertilizer. In developing countries in particular, nitrogen fertilization rates are spiraling upward, driving up fossil-fuel consumption, DeLuca said. Meanwhile, cyanobacteria naturally occurring in farm soils aren’t fixing nitrogen at all in the presence of all that fertilizer, they just don’t expend the energy when nitrogen is so readily available, he said.

“Although modest in comparison to modern fertilization, the observation that cyanobacteria could drive the productivity of these boreal floodplain systems so effectively for so long makes one question whether cyanobacteria could be used to maintain the productivity of agricultural systems, without large synthetic nitrogen fertilizer inputs,” he said.

______________________

Source Credit: Sandra Hines, University of Washington press release.

Co-authors of the paper are Olle Zackrisson and Ingela Bergman with the Institute for Subarctic Landscape Research, Sweden, Beatriz Díez

20131115-120112.jpg
Photo,Sedges and willow trees get the nitrogen they need from cyanobacteria living in the sediments of pristine boreal floodplains found at 60 degrees latitude and north into the Arctic Circle. Credit: T DeLuca/U of Washington

Original article:
popular archaeology.com
November 6, 2013

Read Full Post »

20130609-121402.jpg

Australopithecus afarensis (pictured in an artist’s impression) had different diets from their ancestors

Topic Ancient diet

A new analysis of early human teeth from extinct fossils has found that they expanded their diets about 3.5 million years ago to include grasses and possibly animals.

Human ancestors’ diet changed 3.5 million years ago

A new analysis of early human teeth from extinct fossils has found that they expanded their diets about 3.5 million years ago to include grasses and possibly animals.

Before this, humanlike creatures – or hominins – ate a forest-based diet similar to modern gorillas and chimps.

Researchers analysed fossilised tooth enamel of 11 species of hominins and other primates found in East Africa.

The findings appear in four papers published in PNAS journal.

Like chimpanzees today, many of our early human ancestors lived in forests and ate a diet of leaves and fruits from trees, shrubs and herbs.

But scientists have now found that this changed 3.5 million years ago in the species Australopithecus afarensis and Kenyanthropus platyops.

Their diet included grasses, sedges, and possibly animals that ate such plants. They also tended to live in the open savannahs of Africa.

The new studies show that they not only lived there, but began to consume progressively more foods from the savannahs.

Researchers looked at samples from 175 hominins of 11 species, ranging from 1.4 to 4.1 million years old.

Their diet was analysed from the chemical make up of their teeth, identifying the carbon isotopes within them.

The ratios of different types of carbon atoms, or isotopes, in fossils can give clues to what a fossil creature ate because different foods have different carbon isotope signatures.

“What we have is chemical information on what our ancestors ate, which in simpler terms is like a piece of food item stuck between their teeth and preserved for millions of years,” said Dr Zeresenay Alemseged, from the California Academy of Sciences, co-author on two of the papers.

“Because feeding is the most important factor determining an organism’s physiology, behaviour and its interaction with the environment, these finds will give us new insight into the evolutionary mechanisms that shaped our evolution.”

It is not yet clear whether the change in diet included animals, but “the possible diets of some of our hominin kin” has been considerably narrowed down, Dr Matt Sponheimer, lead author of another of the papers, told BBC News.

A new habitat

“We now have good evidence that some early hominins began using plant foods that are not used in abundance by living African apes today, and this probably led to a major change in the way they used the landscape.

“One consequence could be that the dietary expansion led to a habitat expansion, as they could travel to more open habitats more efficiently.

“We know that many early hominins lived in areas that would not have readily supported chimpanzees with their strong preference for forest fruits. It could also be argued that this dietary expansion was a key element in hominin diversification.”

The study has also answered, at least in part, what researchers have long been speculating – how so many large species of primate managed to co-exist.

“They were not competing for the same foods,” said Prof Thure Cerling from the University of Utah, who led one of the research papers.

‘The modern human’

“All these species who were once in the human lineage, ventured out into this new world of foods 3.5 million years ago, but we don’t yet understand why that is.”

As well as looking at non-human primates, the researchers analysed fossils from other animals from the same era and did not find any evidence of a change in diet.

This combined research highlights a “step towards becoming the modern human”, said Dr Jonathan Wynn from the University of South Florida, who led the analysis of Australopithecus afarensis.

“Exploring new environments and testing new foods, ultimately might be correlated with further changes in human history.”

These four complementary studies give a persuasive account of shifts in dietary niche in East African hominins, Dr Louise Humphrey from the Natural History Museum in London, told BBC news.

Original article:
BBC.co.uk
By Melissa Hogenboom
Science reporter, BBC News
June 4, 2013

20130609-121559.jpg
The teeth of fossils 3.5 million years old give scientists clues to their diet

Read Full Post »

20130107-104736.jpg

Topic: Ancient Diet

Researchers involved in a new study led by Oxford University have found that between three million and 3.5 million years ago, the diet of our very early ancestors in central Africa is likely to have consisted mainly of tropical grasses and sedges. The findings are published in the early online edition of Proceedings of the National Academy of Sciences.

An international research team extracted information from the fossilised teeth of three Australopithecus bahrelghazali individuals — the first early hominins excavated at two sites in Chad. Professor Julia Lee-Thorp from Oxford University with researchers from Chad, France and the US analysed the carbon isotope ratios in the teeth and found the signature of a diet rich in foods derived from C4 plants.

Professor Lee-Thorp, a specialist in isotopic analyses of fossil tooth enamel, from the Research Laboratory for Archaeology and the History of Art, said: “We found evidence suggesting that early hominins, in central Africa at least, ate a diet mainly composed of tropical grasses and sedges. No African great apes, including chimpanzees, eat this type of food despite the fact it grows in abundance in tropical and subtropical regions. The only notable exception is the savannah baboon which still forages for these types of plants today. We were surprised to discover that early hominins appear to have consumed more than even the baboons.”

The research paper suggests this discovery demonstrates how early hominins experienced a shift in their diet relatively early, at least in Central Africa. The finding is significant in signalling how early humans were able to survive in open landscapes with few trees, rather than sticking only to types of terrain containing many trees. This allowed them to move out of the earliest ancestral forests or denser woodlands, and occupy and exploit new environments much farther afield, says the study.

The fossils of the three individuals, ranging between three million and 3.5 million years old, originate from two sites in the Djurab desert. Today this is a dry, hyper-arid environment near the ancient Bahr el Ghazal channel which links the southern and northern Lake Chad sub-basins. However, in their paper the authors observe that at the time when Australopithecus bahrelghazali roamed, the area would have had reeds and sedges growing around a network of shallow lakes, with floodplains and wooded grasslands beyond.

Previously, it was widely believed that early human ancestors acquired tougher tooth enamel, large grinding teeth and powerful muscles so they could eat foods like hard nuts and seeds. This research finding suggests that the diet of early hominins diverged from that of the standard great ape at a much earlier stage. The authors argue that it is unlikely that the hominins would have eaten the leaves of the tropical grasses as they would have been too abrasive and tough to break down and digest. Instead, they suggest that these early hominins may have relied on the roots, corms and bulbs at the base of the plant.

Professor Lee-Thorp said: “Based on our carbon isotope data we can’t exclude the possibility that the hominins’ diets may have included animals that in turn ate the tropical grasses. But as neither humans nor other primates have diets rich in animal food, and of course the hominins are not equipped as carnivores are with sharp teeth, we can assume that they ate the tropical grasses and the sedges directly.”

Original article:
sciencedaily.com

Read Full Post »

%d bloggers like this: