Wednesday, August 12, 2026

Rethinking the earliest stages of cereal domestication

New integrated isotope study shows early increases in cereal grain size were driven by growing conditions rather than human selection

Kiel University

Hiking to Sharara — image:
The Sharara team hiking to the excavation.
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Credit: Jerome Poulalier, www.jerome-poulalier-photography.com

Around 11,000 years ago, Neolithic communities across southwest Asia began producing their own food by bringing wild cereals, legumes and fruit-bearing plants under cultivation. Over the following millennia, these practices transformed hunter-gatherer lifeways and eventually gave rise to farming societies in which domesticated cereal crops were central to subsistence, storage and the accumulation of surplus.

Wild cereals naturally possess a brittle, or shattering, rachis that allows mature seeds to disperse easily, promoting successful germination in the wild but making seed harvesting by people difficult. In comparison to later domestic cereals, wild cereals also have relatively small grains. Decades of archaeobotanical research have shown that systematic cultivation of cereal crops gradually selected for larger grains and a tough rachis that keeps seeds attached to the ear after ripening, making harvesting more efficient.

"Crop domestication was a highly variable and protracted process that unfolded across multiple regions of southwest Asia," said Dr Jade Whitlam (University of Oxford), who led the study. "Over the past decade, archaeobotanical research has revealed that domestication was preceded by a lengthy period of ‘pre-domestication cultivation’, which is thought to have created the conditions that favoured the evolution of key domestication traits”.

Previous studies have interpreted larger cereal grains and the appearance of plants that would later become weeds of cultivation at Early Neolithic sites as evidence that people were already tilling soils and that selection for domestication traits was already underway. Larger grains recovered from southern Levantine sites have therefore often been viewed as among the earliest indicators of domestication.

"At el-Hemmeh and Sharara, both barley and emmer wheat remained morphologically wild in the initial phases of the Pre-Pottery Neolithic, with no evidence of domesticated non-shattering forms", said Dr Whitlam. "Yet grain size varied dramatically, ranging from typically wild-sized grains to grains that were comparable in size to domesticated cereals. At the same time, ecological analysis of weedy plant taxa associated with these cereals indicates they were growing in low disturbance environments, challenging the idea that larger grains were selected for through cultivation practices such as systematic tillage."

To investigate what was driving these differences, the team carried out stable carbon isotope analysis on the charred cereal grains. The stable carbon isotopic composition of cereal grains is strongly influenced by the moisture available to plants as they grow, allowing the team to infer their growing conditions.

“Interestingly, the barley grains that fall within the size range of domestic-sized grains show carbon isotope values indicating they grew under wetter conditions”, said Dr Pascal Flohr (University of Kiel and the University of Oxford), who has carried out extensive field-based experimental work in Jordan establishing the relationship between water stress and the carbon isotopic composition of cereals. “In contrast, the smaller‚ wild-sized grains have isotope values that indicate they grew under much drier conditions, revealing that water availability had a major influence on grain size”.

"Once we integrated the archaeobotanical, weed ecological and isotopic evidence, it became clear that environmental conditions provided a much better explanation for the observed variation in grain size than genetic selection under tillage," said Dr Whitlam. "Our findings show that developmental plasticity rather than genetic change accounts for initial increases in cereal grain size in the Early Holocene southern Levant. This suggests that genetic selection for larger grain size may have occurred later than previously thought, perhaps only after selection for the non-shattering rachis."

"This study demonstrates the value of bringing together long-term archaeological field projects with new analytical approaches. By integrating evidence from archaeobotany, stable isotopes and plant ecology, we can ask entirely new questions about how the transition to agriculture unfolded/. Taken together, these findings suggest that Early Neolithic plant management practices appear to have been part of the long history of hunter-gatherer niche construction rather than a radical new intention to domesticate.” says Professor Cheryl Makarewicz, senior author of the study and director of the excavations at el-Hemmeh and Sharara, the latter with her colleague Dr. Bill Finlayson (Oxford), also a co-author on this research.

Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2535274123

Article Title

Developmental plasticity under human management shaped cereal evolution prior to domestication in the Early Holocene southern Levant

Article Publication Date

14-Aug-2026

First author Jade Whitlam carrying out flotation of the Sharara charred seeds in the Wadi el-Hasa.

Credit

Jerome Poulalier, www.jerome-poulalier-photography.com

Professor Cheryl Makarewicz, senior author of the study, investigating a early neolithic domestic structure at Sharara.

Credit

Jerome Poulalier, www.jerome-poulalier-photography.com

Study uncovers pre-cancerous link between air pollution exposure and lung cancer risk

Emory University

A new study, published Tuesday in Nature Communications, found measurable changes in people’s blood relative to their exposure to air pollution and subsequent development of lung cancer. The findings provide promising clues that could help shape future cancer research, detection, and prevention strategies.

Air pollution exposure is already widely recognized as a key environmental cause of lung cancer. However, less is known about what changes in a person’s body following exposure to air pollution that leads to these adverse health effects.

This new study—led by researchers at the American Cancer Society (ACS) and Emory University’s Rollins School of Public Health—found molecular signs of changes in the blood of people who had been exposed to air pollution and these changes were detectable several years before participants were diagnosed with lung cancer.

The researchers analyzed blood samples from 1,357 cancer-free people in the ACS Cancer Prevention Study cohorts and found changes in small molecules, called metabolites, that were linked to higher long-term air pollution exposure. These disruptions to the body’s normal chemistry involved inflammation, oxidative stress, detoxification, and energy metabolism, which are associated with increased lung cancer risk.

WHY THIS MATTERS

Lung cancer is the leading cause of cancer death in the U.S. and long-term exposure to ambient air pollution is a well-established environmental risk factor for lung cancer and other respiratory diseases, including asthma and chronic obstructive pulmonary disease. However, regular lung cancer screenings are currently only recommended for adults aged 50-80 years old with a substantial history of tobacco smoking.

The air pollution-related biological changes the study identified could guide future development of blood-based biomarkers to help identify more people with higher lung cancer risks and strengthen the evidence for prevention-focused public health strategies.

WHAT THE EXPERTS SAY

“Outdoor air pollution is classified as a human carcinogen, and in epidemiologic studies the association with lung cancer is often strongest among people who have never smoked,” says Ying Wang, PhD, senior principal scientist of epidemiology research at the American Cancer Society, and a co-senior author of the study. “That tells us something meaningful is happening biologically, but we still don’t understand the mechanisms. Studies like this one, which look at what is measurably changing in the body years before a diagnosis, are how we begin to close that gap.”

“Although smoking is a key risk factor for lung cancer, more than half of lung cancer is diagnosed among people who never smoke or who have ever smoked but ineligible for lung cancer screening. Understanding non-smoking related risk factors, such as air pollution, is important for cancer prevention and early detection. But the fact that these environmental risk factors are not even considered in the lung cancer screening recommendations highlights that there's still so much unknown about how air pollution contributes to lung cancer,” says Donghai Liang, PhD, associate professor of environmental health at the Rollins School of Public Health and a co-senior author of the study.

“What is especially exciting about this study is that we now identified measurable changes in human blood metabolome associated with air pollution exposure years before lung cancer was diagnosed,” Liang adds. “These new findings give us a clearer picture of the biological processes connecting air pollution and lung cancer. And with further validation, maybe one day, it could help us identify people at elevated risk and determine whether air pollution exposure should be considered in future prevention and screening strategies.”