Mónica Aguilera, an engineer from the Vegetable Physiology Unit at the University of Barcelona (UB) and co-author of the study, told SINC that the natural levels of stable carbon and nitrogen isotopes were measured in order to estimate the yield and nutritional status of the ancient crops. “The size of the grain and levels of the carbon 13 (13C) isotopes allowed us to estimate yield, while the nutritional status of the crop was analysed by measuring levels of the nitrogen 15 (15N) isotopes,” the researcher explained.
Figures revealed by the study show a reduction of around 35% in the yield of wheat crops and 30% in barley between the years 4000 and 2500 BCE (end of the Bronze Age). The average weight of the grains of these cereals also fell by 10 miligrammes (33%) and 12 mg (38%) respectively. The research also revealed a 33% reduction in the nitrogen content of the wheat grains and 56% in barley.
“These figures suggest that the agricultural system of the region in the south east of the peninsula became unsustainable over time, and that this was not due to a lack of water,” says Aguilera. The scientists have looked into the water available to the cereals by the end of their cultivation period, based upon the carbon isotope component, and have obtained approximately constant values (around 120 mm) for the entire period studied, which makes it seem the decline in yield had no apparent relation to drought events. These estimates, however, contrast with current rain measurements in the area (around 60 mm in April and May).
The researchers have also observed a close relationship between the seasonal variations of the cereals and those of weeds. Barley was most abundant at the same time as wasteland weeds (common in uncultivated land and rubbish tips, such as nettles, mallow, celery, goosefoot and clover), while wheat flourished at the same time as weeds more characteristic of land cultivated with cereals (such as poppies, plantains, knotweeds and various grassy plants).
“This suggests that there was a separate system of cultivation for the two cereals: barley was possibly relegated to marginal areas, while the potentially more fertile fields were reserved for wheat, which was more abundant and very probably the principal crop for human consumption in the primitive agricultural systems of the south east of the peninsula,” said Aguilera.
The results of the study show a link between the decline in the status of the crops and a progressive loss in soil fertility, and reinforce the hypothesis that the first agricultural activities in the Mediterranean area had a negative impact on ecological and environmental conditions there.
The scientists chose the Los Castillejos archaeological site because it shows evidence of a continuous period of cereal cultivation over more than 1,500 years, starting in the Neolithic, when agriculture first appears in the region. However, they have contrasted their data with other results from Arkaute (Álava), Guadahortuna (Granada) and various areas in Catalonia and Castilla-La Mancha, as well as with other sites in Syria and the eastern Mediterranean.
Researchers from the University of Barcelona, the University of Lleida and the Archaeology Museum of Catalonia, as well as archaeologists from the University of Granada and the Andalusian Centre for Iberian Archaeology (University of Jaén), took part in the study, “which uses original means to apply a range of novel methodologies derived from the use of stable carbon and nitrogen isotopes in palaeoclimatic and environmental reconstruction,” according to Aguilera.
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Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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