Crusaders: Echoes from the Deep Heart of Europe

When we picture the medieval Crusaders who stormed into the Levant nearly a thousand years ago, we often imagine armored knights from France, Germany, or England, answering the Pope's call to defend Christendom. But a groundbreaking genetic study published in The American Journal of Human Genetics (Haber et al., 2019) invites us to go far beyond the surface of medieval history — right into the DNA of these long-dead warriors.

Excavating the Past through Ancient Genomes

In the heart of Sidon, a major port city in present-day Lebanon, archaeologists uncovered a mass burial associated with a violent episode from the time of the Crusades. Geneticists extracted DNA from the remains and successfully sequenced six individuals (labeled SI-40 through SI-47). These sequences offer a rare window into who the Crusaders really were — and who they became.

Deep European Roots

Sample SI-47, for instance, carried the Y-chromosome haplogroup R-M269, a lineage widespread in Western Europe. Based on his autosomal DNA, this individual shows clear genetic affinity with populations from northern France or perhaps the Low Countries, regions that historically contributed heavily to the Crusader armies. He is, genetically speaking, a representative of medieval northern Europe.

But he's not alone.

Another sample, SI-41, carries haplogroup DF27, a branch typically found in southwestern Europe, particularly Iberia and parts of southern France. However, this individual displays a mixed genetic profile — part European, part local Near Eastern — suggesting that admixture had already occurred, possibly within a single generation. Crusaders weren’t just fighting — they were also integrating.

A Genetic Mix on the Frontlines

Samples SI-40 and SI-41 show particularly strong signs of admixture, with European Y-chromosomes but autosomal DNA that suggests local ancestry. This paints a vivid picture of rapid and direct genetic mixing during the Crusader period. Whether through intermarriage, local birth, or assimilation, some Crusaders were not just passing through the Levant — they were becoming part of it.

The cemetery at Sidon thus reflects a remarkable demographic reality: the Crusades were not a one-way migration, but a dynamic human exchange. European warriors didn’t just bring their weapons; they brought their genes, their families, and eventually, their descendants.

Raw Data from the Sidon Crusader Genomes

For those interested in further analysis or visualization, here are the 25-dimensional G25 coordinates for each of the six individuals sequenced in the study Haber et al., 2019:

Copy

Lebanon_Medieval_o5.SG:SI-40_noUDG.SG,0.124067,0.153345,0.048649,0.003876,0.046778,0.005578,-0.016686,0.010846,0.029042,0.033167,-0.001949,0.008842,-0.013231,-0.025047,0.011129,0.008353,0.004563,0.011149,0.012444,0.01113,0.014849,-0.009274,0.001849,-0.005904,-0.001557
Lebanon_Medieval_o1.SG:SI-41_noUDG.SG,0.072847,0.148267,0.016593,-0.031977,0.040623,-0.016176,-0.011516,0.006461,0.025565,0.029522,-0.000974,0.012739,-0.002527,-0.012661,0.006107,0.000928,-0.000913,-0.003421,-0.006913,0.005753,0.001248,-0.005935,0.005423,0.003615,0.004071
Lebanon_Medieval.SG:SI-42_noUDG.SG,0.071709,0.151314,-0.046009,-0.091086,-0.005232,-0.027052,-0.00752,-0.018922,0.014521,0.010205,0.012179,-0.008093,0.012339,0.004817,-0.0076,-0.012861,-0.012517,-0.002027,0.000754,-0.013757,0.003119,0.014962,-0.005916,0.009037,0.010777
Lebanon_Medieval_o3.SG:SI-44_noUDG.SG,0.100164,0.159438,-0.038843,-0.079458,0.002154,-0.03012,-0.001175,-0.017076,-0.00634,0.022233,0.013316,-0.002548,0.001189,0.000688,-0.014658,0.001326,0.00013,-0.000253,0.016341,-0.007629,-0.005989,-0.009769,-0.000616,-0.007832,0.004071
Lebanon_Medieval.SG:SI-45_noUDG.SG,0.080814,0.149283,-0.059208,-0.081396,-0.010156,-0.034304,-0.009165,-0.010153,-0.000614,0.012939,-0.000487,-0.008243,0.003568,-0.00234,-0.006379,-0.000928,0.000261,0.000253,-0.001131,-0.001126,0.000499,-0.004699,-0.000986,-0.000723,0.00479
Lebanon_Medieval_o2.SG:SI-47_noUDG.SG,0.126344,0.137096,0.067882,0.02907,0.0397,0.009482,0.00047,0.005307,0.008181,-0.000364,-0.005521,0.011839,-0.005798,-0.014313,0.011672,0.004906,-0.002999,-0.008108,-0.011061,-0.003252,0.007112,0.006677,0.002835,-0.001446,0.007424

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