Evolution of wheat spikes since the Neolithic revolution

Around 12,000 years ago, the Neolithic revolution radically changed the economy, diet and structure of the first human societies in the Fertile Crescent of the Near East. With the beginning of the cultivation of cereals -- such as wheat and barley -- and the domestication of animals, the first cities emerged in a new social context marked by a productive economy. Now, a study published in the journal Trends in Plant Science and co-led by the University of Barcelona, the Agrotecnio centre and the University of Lleida, analyses the evolution of wheat spikes since its cultivation began by the inhabitants of ancient Mesopotamia -- the cradle of agriculture in the world -- between the Tigris and the Euphrates.

The authors of the study are Rut Sánchez-Bragado and Josep Lluís Araus-Ortega, from the UB Faculty of Biology and Agrotecnio-UdL; Gustavo A. Slafer, ICREA researcher at the UdL School of Agrifood and Forestry Science and Engineering, and Gemma Molero, from the International Maize and Wheat Improvement Center in Mexico, currently a researcher at KWS Seeds Inc.

A cereal that changed human history

The cultivation of wheat -- a grass that became basic food -- represented a turning point in the progress of human civilisation. Today it is the world's most important crop in terms of food security, but EU data warn that the impact of climate change could significantly increase its price and modify its production process in certain areas of the world.

Throughout the domestication process of wheat, the plant phenotype has undergone both rapid (within a few hundred years) and slow (thousands of years) changes, such as the weakening of the rachis, the increase in seed size, and the reduction or disappearance of the awns. In particular, awned and awnless wheat varieties are found all over the world, although the latter tend to be abundant in regions with arid climates, especially during the final stages of cultivation in late spring, a condition typical of Mediterranean environments.

"It is important to conduct studies that show which wheat varieties are best adapted to different environmental growing conditions, especially in a context of climate change. Studying the past retrospectively can give us an idea of the evolution of wheat cultivation over the millennia since agriculture appeared in ancient Mesopotamia," says Rut Sánchez-Bragado, first author of the study, who got a PhD at the UB.

"Awns are organs of the spike that have traditionally been associated with the plant's adaptations to drought conditions," says Josep Lluís Araus, professor at the Department of Evolutionary Biology, Ecology and Environmental Sciences of the Faculty of Biology.

"However, archaeological and historical records show that the wheat spike has existed predominantly with awns for more than ten millennia after the domestication of wheat. It is not until the last millennium that evidence shows in many cases the absence of awns, indicating a selection by farmers -- probably in an undirected way -- against this organ," stresses Araus, one of the most cited authors in the world according to Clarivate Analytics' Highly Cited Researchers (2022).

"The role of wheat awns in their performance remains controversial despite decades of studies," says researcher Gustavo A. Slafer, corresponding author of the study.

Spike awns: beneficial for the plant?

Is the presence of awns on the spike beneficial for the plant and the crops? Although there is no scientific consensus, "everything suggests that in conditions where the plant does not suffer from water stress, the extra photosynthetic capacity of the awns does not compensate for other potential negative effects (reduced susceptibility to fungal diseases, limitation in the total number of large ones that an ear supports, etc.)," says Araus.

"However, in wetter climates the awns accumulate moisture and can promote the spread of diseases," says Rut Sánchez-Bragado. "So, as the world's population is continuously growing, it is necessary to investigate the role of the awned spikes in the changing conditions of our climate in order to meet the world's demand for a primary food commodity such as wheat."

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Just 10 financial actors hold the key to climate change

A new report has identified the 10 financial actors with the most influence on the fossil fuel economy and outlines the decisive role they can play in helping de-carbonize our future.

The study found that the top 10 most influential actors, including investment advisors, governments, and sovereign wealth funds from around the world, own 49.5 per cent of potential emissions from the world's largest energy firms.

"This shows us that both investors and governments can be at the forefront of change if citizens and clients urge them to de-carbonize," said Truzaar Dordi, lead researcher from the University of Waterloo. "A concentrated number of investors with the potential to influence the trajectory of the fossil fuel industry is either a problem, or an opportunity, depending on how you see things."

To arrive at their list, the researchers used a novel scoring mechanism blending the financial actor's fossil fuel holdings and investment in the world's 200 largest fossil fuel firms.

"If they're serious, capital markets can enable a low-carbon transition within the top coal, oil and gas reserve owners in the world," said Dordi. "Recent pledges to reduce carbon exposure in investment portfolios and engagement with the fossil fuel industry indicate we may already be moving in that direction."

The paper outlines specific ways these 10 governments and private investment advisors can make changes that will have a transformative impact in the fight against climate change. Some recommendations include public disclosure of a scheduled phase-out of fossil fuel financing, an assessment of a portfolio's exposure to climate risk in a 2°C world, and an alignment of investment portfolios with a 1.5°C scenario.

"Individually, reducing the demand for fossil fuels by driving and flying less and turning off the air-conditioner are great. We should keep doing that. But we also need to reduce our production of fossil fuels, which these 10 actors can lead. Without them, we simply won't have what it takes to meet our emissions targets and avoid catastrophe."

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Who wants to be a billionaire? Most don't -- which is good news for the planet

A founding economic principle that everyone is motivated by 'unlimited wants', stuck on a consumerist treadmill and striving to accumulate as much wealth as they can, is untrue, say the authors of a new study.

The long-held economic belief that people have unlimited wants has permeated economic thinking and government policies and has shaped much of modern society, including advertising and consumerism.

But belief in this principle has also had dire consequences for the health of the planet. Striving to continually increase individual wealth, and pursuing unending economic growth, has come at a heavy cost. As wealth has increased, so too has resource use and pollution.

Up until now, researchers have struggled to find appropriate ways to decouple economic growth from damaging economic principles. Now though, a new study led by psychologists at the universities of Bath, Bath Spa and Exeter challenges the idea that unlimited wants are human nature, which could have important implications for the planet.

Across nearly 8000 people from 33 countries spanning six continents, they surveyed how much money people wanted to achieve their 'absolutely ideal life'. In 86% of countries most people thought they could achieve this with US $10 million or less, and in some countries as little as $1 million.

Whilst these figures may still sound a lot, when considered that they represent a person's ideal wealth across their whole life they are relatively moderate. Expressed differently, the wealth of the world's single richest person, at over $200 billion, is enough for more than two hundred thousand people to achieve their 'absolutely ideal lives'.

The researchers collected responses about ideal wealth from individuals in countries across all inhabited continents, including countries rarely used in cross-cultural psychology such as Saudi Arabia, Uganda, Tunisia, Nicaragua, and Vietnam. People with unlimited wants were identified in every country, but they were always in the minority.

They found that those with unlimited wants tended to be younger and city-dwellers, who placed more value on success, power, and independence. Unlimited wants were also more common in countries with greater acceptance of inequality and in countries that are more collectivistic: focused more on group than individual responsibilities and outcomes.

For example, Indonesia, which is considered more collectivistic and accepting of inequality, had the most people with unlimited wants whilst the more individualistic and equality-concerned UK had fewer. However, there were anomalies like China, where few people had unlimited wants despite high cultural collectivism and acceptance of inequality.

Lead researcher, Dr Paul Bain from the Department of Psychology at the University of Bath (UK) explained: "The ideology of unlimited wants, when portrayed as human nature, can create social pressure for people to buy more than they actually want.

"Discovering that most people's ideal lives are actually quite moderate could make it socially easier for people to behave in ways that are more aligned with what makes them genuinely happy and to support stronger policies to help safeguard the planet."

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Scientists show large impact of controlling humidity on greenhouse gas emissions

Greenhouse gas emissions from air conditioners are expected to climb as economic growth drives efforts to control both temperature and humidity, according to an analysis by scientists from the National Renewable Energy Laboratory and Xerox PARC.

The research, which explores the environmental impact of controlling humidity, appears in the journal Joule as "Humidity's impact on greenhouse gas emissions from air conditioning." While the energy used to power air conditioners has clear implications on greenhouse gas emissions, the impact from removing moisture from the air has escaped in-depth study until now. The researchers showed that controlling humidity is responsible for roughly half of the energy-related emissions, with the other half due to controlling temperature.

"It's a challenging problem that people haven't solved since air conditioners became commonplaces more than a half-century ago," said Jason Woods, an NREL senior research engineer and co-author of the new study. His co-authors from NREL are Nelson James, Eric Kozubal, and Eric Bonnema. The collaborators from Xerox PARC, an R&D company working on ways to remove humidity more efficiently from the air, are Kristin Brief, Liz Voeller, and Jessy Rivest.

The researchers pointed out the increasing need to cool the air is both a cause and an effect of climate change.

Even a small amount of moisture in the air can cause people to feel uncomfortable and even damage buildings in the form of mold and mildew. Furthermore, controlling indoor humidity through commercially available air conditioning technologies impacts the environment in three ways: 1) They consume a considerable amount of electricity, 2) they use and leak CFC-based refrigerants with global warming potential that is 2,000 times as potent as carbon dioxide, and 3) the manufacturing and delivery of these systems also release greenhouse gases.

The researchers calculated air conditioning is responsible for the equivalent of 1,950 million tons of carbon dioxide released annually, or 3.94% of global greenhouse gas emissions. Of that figure, 531 million tons comes from energy expended to control the temperature and 599 million tons from removing humidity. The balance of the 1,950 million tons of the carbon dioxide come from leakage of global-warming-causing refrigerants and from emissions during the manufacturing and transport of the air conditioning equipment. Managing humidity with air conditioners contributes more to climate change than controlling temperature does. The problem is expected to worsen as consumers in more countries -- particularly in India, China, and Indonesia -- rapidly install many more air conditioners.

"It's a good and a bad thing," Woods said. "It's good that more people can benefit from improved comfort, but it also means a lot more energy is used, and carbon emissions are increased."

To calculate the emissions to manage both temperature and humidity, the researchers divided the globe into a fine grid measuring 1 degree of latitude by 1 degree of longitude. Within each grid cell, the following characteristics were considered: population, gross domestic product, estimated air conditioner ownership per capita, carbon intensity of the grid, and hourly weather. They ran nearly 27,000 simulations across the globe for representative commercial and residential buildings.

Climate change is affecting ambient temperatures and humidity around the globe, making it warmer and more humid. As part of the study, the researchers considered the impact of the changing climate on air conditioner energy use by 2050. For example, the study projects air conditioner energy use to increase by 14% in the hottest climate studied (Chennai, India) and by 41% in the mildest (Milan, Italy) by 2050. The increase in global humidity is projected to have a larger impact on emissions than the increase in global temperatures.

"We've already made the existing, century-old technology nearly as efficient as possible," Woods said. "To get a transformational change in efficiency, we need to look at different approaches without the limitations of the existing one."

Existing vapor compression technology is optimized to cool our buildings using a "vapor compression cycle." This cycle uses harmful refrigerants to cool air down low enough to wring out its moisture, often over-cooling the air and wasting energy. Improving the vapor compression cycle is reaching practical and theoretical limits, thus pointing to a need to leap-frog to an entirely new way to cool and dehumidify buildings. New technologies that split this cooling and humidity control problem into two processes show potential to improve efficiency by 40% or more. Once such technology space is the use of liquid desiccant-based cooling cycles such as the many liquid desiccant air conditioning technologies that NREL is currently developing with many partners, such as Emerson and Blue Frontier.

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Heat stress for cattle may cost billions by century's end, study finds

Climate change poses a potentially devastating economic threat to low-income cattle farmers in poor countries due to increasing heat stress on the animals. Globally, by the end of this century those producers may face financial loss between $15 and $40 billion annually.

Farmers in tropical regions -- including large parts of South America, Asia and Africa -- are likely to suffer significantly, particularly when compared with producers in the world's wealthier temperate zones, according to a study by an international team of scientists and economists published in the Lancet Planetary Health.

The researchers, including Mario Herrero, professor of sustainable food systems at Cornell University, and lead author Philip Thornton, of the International Livestock Research Institute and CGIAR; published "Impacts of Heat Stress on Global Cattle Production During the 21st Century."

Escalating demand for livestock products in low- and middle-income countries, along with steadily increasing global average temperatures, is an uncomfortable mix, the researchers said. If livestock are to adapt to new thermal environments and increase their productivity, infrastructural investments or adjustments -- such as switching to more heat-tolerant cattle breeds, and improving shade, ventilation and cooling systems -- will be required.

In the paper's high greenhouse-gas emission scenario, cattle production losses from heat stress are estimated to be $39.94 billion annually, or 9.8% of the value of production of meat and milk from cattle in 2005 -- the scientists' baseline year. The low-emission scenario projects production losses at $14.9 billion annually, or 3.7% of the 2005 value.

By the end of the century, dairy and beef production in the United States is projected to decline by 6.8%, while India -- a major dairy production country -- is projected to lose more than 45% of its dairy farming due to heat stress increases.

"Resource-poor farmers in low-income countries depend heavily on their livestock for their livelihoods," Thornton said. "The adaptation needs are even higher in these countries, and those farmers are the ones where the hit is even more severe."

With climate change, farming and sustainability, Herrero suggested there is a need to create equitable adaptation practices "by design and to think intentionally on reaching the vulnerable sectors of global society," he said. "We cannot just hope that the poor will not be affected."

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Hyena scavenging provides public health and economic benefits to African cities

Hyenas are frequently vilified and often feared. Hemingway once described the hyena as a stinking, foul devourer of the dead, with jaws that crack the bones the lion leaves.

But a new study concludes that spotted hyena scavenging provides significant public health and economic benefits to the African cities they roam.

In a study conducted in and around the Ethiopian city of Mekelle, home to 310,000 people and 120,000 livestock animals, a University of Michigan conservation ecologist and two colleagues found that spotted hyenas annually remove 207 tons of animal carcass waste.

Mekelle is the capital of northern Ethiopia's Tigray region. The carcasses of livestock animals that are slaughtered for food there, or that die naturally, are often dumped at the local landfill or on roadsides, where hyenas feed on the waste. The researchers wanted to know whether hyenas -- by removing this waste from the environment -- might also prevent pathogens from jumping into people and livestock.

They determined that hyena scavenging annually prevents five infections of anthrax and bovine tuberculosis in Mekelle residents and 140 infections in cattle, sheep and goats. This disease-control service potentially saves the city $52,000 annually in treatment costs and livestock losses avoided.

The study, published online Sept. 26 in the Journal of Applied Ecology, is the first to quantify the public health and economic benefits of scavenging by spotted hyenas.

"Yes, the effects are modest. Even so, this study totally upends the traditional narrative around hyenas -- that they are a nuisance and should be removed," said U-M's Neil Carter, senior author of the study and an assistant professor at the School for Environment and Sustainability. "This is an important contribution to a growing body of work that highlights the benefits of predators and scavengers, rather than focusing only on their costs to humanity."

The authors emphasize that these sanitation and disease-control services are particularly valuable in low-income and rural areas. In Mekelle, the scavenging behavior of hyenas advances three U.N. Sustainable Development Goals: ensuring good health and well-being, providing clean water and sanitation, and promoting terrestrial biodiversity.

To estimate the benefits of spotted hyenas, the researchers examined their feeding habits and the population size around Mekelle. During the daytime, the Mekelle hyenas rest at sites outside the city to avoid human disturbances; they come into the city at night to feed.

The field data were collected and analyzed by study lead author Chinmay Sonawane, a former student of Carter's who is now a doctoral student at Stanford University.

Those data were integrated into a disease transmission model used to predict the number of anthrax and bovine tuberculosis infections arising in humans and livestock from infected carcass waste, as well as the costs associated with treating those infections and losing livestock. The researchers compared these public health and economic outcomes under two scenarios: hyenas present and hyenas absent.

"In comparison to the large cattle enterprises in the Global North, the benefits that we found are quite small," Sonawane said. "However, losing even a single cow to anthrax or bovine tuberculosis can cause significant financial stress to cattle owners in Ethiopia, who tend to own much smaller herds of cattle than cattle owners in other parts of the world.

"In addition, we only estimated the benefits accrued from hyenas within 5 kilometers of the city. It is very, very likely that hyenas much further than 5 kilometers are coming into Mekelle and consuming even more waste."

For Sonawane, the fieldwork involved spending nights at the Mekelle landfill and recording the number and type of animal carcasses (mostly cattle, horses, chickens, sheep and goats) available to the scavengers.

He counted the hyenas and watched them feed, using night-vision binoculars that operate at infrared wavelengths. The black-and-white photos and video clips he captured are haunting: the eyes of the hyenas glow with an unearthly fire.

The study authors determined that an individual Mekelle hyena annually scavenges about 2,100 pounds of carcass waste around the city. For hyenas feeding at the landfill, horse carcasses accounted for about 80% of that total, while poultry waste was the most frequently consumed type of animal carcass waste.

The researchers estimated a population size of 210 hyenas around Mekelle using "call-in surveys." This field method involved broadcasting prerecorded hyena distress calls with a 45-watt megaphone from the top of a vehicle at five locations around the city. During each hour-long survey, the researchers counted the number of hyenas attracted to the sounds and visible with the night-vision binoculars.

Given the consumption rate and the estimated population size, the Mekelle hyenas were expected to annually remove 207 metric tons of animal carcass waste, which is 4.2% of the total animal carcass waste thrown away by residents and businesses.

Waste generation in Mekelle is expected to increase with the exponentially growing human population there, Carter and his colleagues wrote: "Given the financial constraints on waste collection and disposal services, sanitary conditions are expected to deteriorate further." Hyena scavenging may, therefore, be even more valuable in the future.

The authors note that the benefits of hyena presence must be weighed against the costs. A 2011 study reported 10 nonfatal hyena attacks on humans annually in Mekelle, along with an estimated economic loss of $2,928 from 33 fatal attacks on cattle and small ruminants annually.

To preserve the public health and financial benefits provided by hyenas into the future, nonlethal management actions that minimize risks and enable hyenas to coexist with humans are necessary, according to the authors.

"By maintaining the hyenas' access to waste, human-hyena conflict can be mitigated in Mekelle, and the sanitation and disease control benefits provided by hyena scavenging can be preserved or even increased," they wrote.

But excluding hyenas from scavenging animal carcass waste may compel them to hunt livestock and could increase human-hyena conflict, as a previous study in Mekelle has shown.

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'Urban green space affects citizens' happiness'

A recent study revealed that as a city becomes more economically developed, its citizens' happiness becomes more directly related to the area of urban green space.

A joint research project by Professor Meeyoung Cha of the School of Computing and her collaborators studied the relationship between green space and citizen happiness by analyzing big data from satellite images of 60 different countries.

Urban green space, including parks, gardens, and riversides not only provides aesthetic pleasure, but also positively affects our health by promoting physical activity and social interactions. Most of the previous research attempting to verify the correlation between urban green space and citizen happiness was based on few developed countries. Therefore, it was difficult to identify whether the positive effects of green space are global, or merely phenomena that depended on the economic state of the country. There have also been limitations in data collection, as it is difficult to visit each location or carry out investigations on a large scale based on aerial photographs.

The research team used data collected by Sentinel-2, a high-resolution satellite operated by the European Space Agency (ESA) to investigate 90 green spaces from 60 different countries around the world. The subjects of analysis were cities with the highest population densities (cities that contain at least 10% of the national population), and the images were obtained during the summer of each region for clarity. Images from the northern hemisphere were obtained between June and September of 2018, and those from the southern hemisphere were obtained between December of 2017 and February of 2018.

The areas of urban green space were then quantified and crossed with data from the World Happiness Report and GDP by country reported by the United Nations in 2018. Using these data, the relationships between green space, the economy, and citizen happiness were analyzed.

The results showed that in all cities, citizen happiness was positively correlated with the area of urban green space regardless of the country's economic state. However, out of the 60 countries studied, the happiness index of the bottom 30 by GDP showed a stronger correlation with economic growth. In countries whose gross national income (GDP per capita) was higher than 38,000 USD, the area of green space acted as a more important factor affecting happiness than economic growth. Data from Seoul was analyzed to represent South Korea, and showed an increased happiness index with increased green areas compared to the past.

The authors point out their work has several policy-level implications. First, public green space should be made accessible to urban dwellers to enhance social support. If public safety in urban parks is not guaranteed, its positive role in social support and happiness may diminish. Also, the meaning of public safety may change; for example, ensuring biological safety will be a priority in keeping urban parks accessible during the COVID-19 pandemic.

Second, urban planning for public green space is needed for both developed and developing countries. As it is challenging or nearly impossible to secure land for green space after the area is developed, urban planning for parks and green space should be considered in developing economies where new cities and suburban areas are rapidly expanding.

Third, recent climate changes can present substantial difficulty in sustaining urban green space. Extreme events such as wild?res, ?oods, droughts, and cold waves could endanger urban forests while global warming could conversely accelerate tree growth in cities due to the urban heat island effect. Thus, more attention must be paid to predict climate changes and discovering their impact on the maintenance of urban green space.

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