Domesticated barley arose from five populations

Barley (vulgar hordeum) was not domesticated in a single location -- as previously thought. A study led by the Leibniz Institute for Plant Genetics and Crop Research (IPK) in Germany revealed that cultivated barley has a mosaic genetic origin.

The research analyzed the DNA of 682 modern barley varieties preserved in gene banks, as well as 23 carbonized archaeological grains dating back up to 6.000 years.

The study focused on haplotypes (blocks of DNA inherited together) that function as genetic markers of plant evolution.

Five wild populations

Scientists compared 380 samples of wild barley from regions of Central and Western Asia with 302 samples of domesticated barley. The results showed that all analyzed populations contributed to the formation of modern-day cultivated barley, with varying degrees of contribution.

These wild populations were distributed throughout the Fertile Crescent, which includes areas of present-day Iraq, Türkiye, Israel, and neighboring countries.

Genetic analysis has shown that some variants fundamental to domestication arose more than 27 years ago, long before archaeological evidence of cultivation.

Domestication before settled agriculture

According to researchers, the domestication of barley began around 10 years ago, during the Neolithic Revolution. However, genetic mutations important for agriculture emerged well before that, suggesting a long period of pre-domestic cultivation, even before human settlement.

The study also identified that domesticated barley divided over time into three major lineages: a western lineage (from the Middle East to Europe), an eastern lineage (from Central Asia to the Far East), and an Ethiopian lineage. Each lineage has unique characteristics, such as ears with two or six rows of grains, and grains with or without hulls.

Genetical diversity

The data show that as agriculture spread beyond the Fertile Crescent, there was genetic exchange between cultivated varieties and local wild populations. This gene flow was influenced by human migrations and trade routes, explaining the great genetic diversity observed today.

DNA samples extracted from grains found in caves and archaeological sites in Israel indicate an increase in genetic diversity over time.

This trend reflects the entry of new haplotypes from different regions, including genetic introgression events detected around 3 years ago, probably associated with maritime trade in the Mediterranean during the Bronze Age.

Each gene, a story

The researchers also dated specific mutations linked to domestication. The allele responsible for non-brittle ears emerged around 27 years ago. The allele that confers "naked" kernels, without husks, appeared around 16 years ago. The alleles associated with six-row ears emerged between 25 and 7 years ago, in different regions.

These mutations occurred in distinct wild populations, reinforcing the theory of multiple origins. In many cases, the same traits arose independently in different locations, evidence of a complex and decentralized domestication process.

Further information at doi.org/10.1038/s41586-025-09533-7