DUBAI (Phys.org) -- Researchers from Khalifa University, United Arab Emirates, working with regional and international collaborators, have examined Yemeni DNA to reveal how migrations from the Levant, Arabia, and East Africa formed the modern Yemeni gene pool. Analysis of Yemeni genomes revealed genetic contributions from both the Levant and East Africa, with significant regional influxes occurring at different historical periods.
The study is published in the journal Scientific Reports.
Yemen has historically served as an important crossroads between Africa, the Arabian Peninsula, and the Levant. Ancient involvement in spice and incense trade networks connected Yemen to Egypt, Sumer, and Dilmun, while Mediterranean trade with Palestine, the Phoenicians, and Greece solidified its role in regional commerce. As wealth grew in Yemen, so did its slavery trade networks with East Africa.
Arabia’s prehistoric population movements in Yemen have only been superficially explored to date. Past genetic assessments explored ancestral ties but lacked precise insights into when and from where ancient groups arrived.
In the study, titled “Human migration from the Levant and Arabia into Yemen since Last Glacial Maximum,” researchers analyzed 46 whole genomes and 169 genotype arrays from Yemeni individuals, along with 351 comparative genotype arrays from neighboring populations.
They specifically looked for signals of migration from the Levant, Iran and ancient trading partners, as well as the presence of Out of Africa genetic signatures in modern Yemeni populations.
Yemen’s paternal Y-chromosome haplogroups were dominated by J1, a marker associated with Southwest Asia, indicating ancient ties to the Levant and Arabia along male decent lines.
Mitochondrial DNA haplogroups revealed substantial African matrilineal influence, with nearly one-third of Yemeni samples carrying African-specific mtDNA haplogroups such as L2a1, the most widespread haplotype in sub-Saharan Africa. This suggests a robust female-mediated gene flow from East Africa into Yemen at some point.
Neanderthal allele frequencies within the population hinted at exchanges that would have taken place early in the Out Of Africa migration and were similar to those found elsewhere in Arabia.
Two major gene flow events emerged from the data, one around 5,220 years ago involving populations in Palestine and another about 750 years ago involving East African groups.
Levantine contributions align with the time of the Bronze Age and earlier migrations, whereas the East African component may reflect the region’s long and intense involvement in slavery. Yemen was a key player in the Red Sea slave trade, particularly involving enslaved people from East Africa.
The medieval forced migration into Yemen would be expected to influence the genomics of the population in very specific ways that seem reflected in the research findings. While male slaves were often forced to undergo castration, enslaved women were most likely to be sexually exploited.
Under ancient Islamic law, Muslims were not allowed to be enslaved. No such rules existed for the enslavement of non-Muslims. Enslaved African women were often forced into harems, and Islamic law legitimized children born from these relationships. Such children had inheritance rights and were considered free.
These practices have been documented, though the scale and specifics have not been extensively studied in Yemen. Slavery was only officially outlawed there in the 1960s.
While the study does not explicitly attribute their findings to ancient slavery practices, data showing predominantly Levantine father and significant African mother haplogroups in the modern population would be difficult to explain otherwise.
When looking at all 22 autosomes, East African alleles show low frequency in most Yemeni groups, except for those in some coastal regions. This difference between the high African maternal haplogroup and low allele frequency implies how substantial the maternal East African influences must have been.
Maternal haplogroups are only passed down from mother to child. Despite generations of admixture with predominantly Levantine/Arabian paternal input diluting the total of East African DNA, an unbroken chain of mothers of East African origin persists in around a third of the population.
While the study suggests that the alleles of the modern population--which cluster more strongly with Saudi Arabian and Bedouin groups--could have been introduced to Yemen more than 5,000 years ago based on the diversity of paternal haplogroups, it is also clear that the Yemeni population best representing its documented history has East African roots as well.
Coastal regions exhibited stronger African admixture in the study, while more northern, inland Yemeni districts indicated tighter genetic ties to Arabia and the Levant. It should not go unnoticed that amidst the long and ongoing civil war in Yemen, the study finds differing historical genomic origin journeys along coastal and inland divisions that overlay well with the demarcated lines of the current conflict.