The Enigmatic Genetic Footprint of Palestine

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A Palestinian man walking toward the Palestinian flag in the South Hebron Hills in the West Bank.
A Palestinian man walking toward the Palestinian flag in the South Hebron Hills in the West Bank.Credit: Olivier Fitoussi
Yasmin Zaher
Yasmin Zaher
Yasmin Zaher
Yasmin Zaher

The Levant is one of the longest-occupied places on Earth, having been continuously settled since ancient humans first set foot out of Africa. Over the ages, masses of people have come and gone through the lands that are today the Palestinian territories and Israel: some migrating, some on a mission to conquer, whether for strategic reasons or attracted by the mystique of the place.

The cultural diversity resulting from this human footprint is encoded in the customs and dialects of the place – and presumably also in the genetic code of its inhabitants. Yet mysterious things happen when Palestinians take DNA tests purporting to deconstruct their genetic ancestry. Some are advised that they are Italian, others that they are Syrian Jews, Yoruba Africans, Egyptian Copts or even Native Americans. The results vary by individual, naturally, but also by the test brand and the methodology it employs.

DNA is a no-nonsense set of data, supposedly objective. Yet as we try to impose on it man-made categories like race, ethnicity and religion, the analysis becomes biased. A main problem skewing results is that, to this day, the vast majority of data available to genetic scientists is of people of European ancestry.

However, as Palestinians and people in the Levant increasingly get sampled, new information comes to light about the region’s genetic history, from mass migrations triggered by droughts in ancient Mesopotamia, to a 3,000-year-old invasion by seed-spreading sailors, to evidence of a marked degree of genetic continuity from ancient times, despite numerous foreign occupations.

When we were Italian

Marguerite Dabaie is a Palestinian-American illustrator living in Brooklyn. Her mother is American of Scottish heritage and her father a first-generation Palestinian immigrant, born in Ramallah. In 2016, Marguerite’s half-brother from her father’s side showed her the results of his 23andMe ancestry test, and asked her to take the test to cross-verify the strange findings.

Marguerite DabaieCredit: Jean Huh

When the results came, Dabaie was surprised to discover that she was half-British, just a tiny bit Arab, and a whole lot Italian. “I was flabbergasted,” she says. “At the time I thought 23andMe can’t be wrong. I was thinking since Palestine was an eclectic port country, maybe a bunch of Italians did land there and propagated and are now considered Palestinian.”

About a year later, Dabaie received what she terms a “nonchalant notification” from 23andMe saying her profile had been updated. All that Italian DNA had transformed to Arab. More specifically, she was now 50 percent Levantine from Lebanon.

“There are many factors affecting the results of these ancestry tests,” explains Mohamed Almarri, a geneticist at the Wellcome Sanger Institute near Cambridge, England. Ancestry is determined by analyzing a person’s mutations (those differences that make each of us unique) and comparing these to a set of references (a group of people representing a race, ethnicity, religion or place). These references may not be comprehensive or may contain mistakes, says Almarri, pointing to a primary limitation of these ancestry tests.

In recent years, reference datasets have been expanding and becoming more diverse due to an active effort by companies to collect genetic samples from unrepresented groups, and also because scientists like Almarri publish their data open source. In Dabaie’s case, 23andMe expanded its reference dataset to include more Levantine people and then updated the algorithm that assigns ethnic categories.

The updated results of Marguerite Dabaie's ancestry test. She was “flabbergasted” after originally being told she was half-British, just a tiny bit Arab and a whole lot Italian. Credit: Marguerite Dabaie

Although 23andMe has millions of customers, its reference dataset for the ancestry composition algorithm – falsely believed by many customers to capture the entire spectrum of human diversity – is composed of less than 15,000 people. According to the company, these were “chosen generally to reflect populations that existed before transcontinental travel and migration were common.”

The Levantine category at 23andMe is made up of 400 reference samples – Jordanians, Lebanese, Syrians and Palestinians. The data relevant to Palestinians was collected by the Human Genome Diversity Project: 46 Palestinians from central Israel; 42 Druze from Mount Carmel; and 46 Bedouin from the Negev. According to Prof. David Gurwitz of Tel Aviv University, who collected these samples some 20 years ago, the ethnicity of donors was self-defined.

The Levantine subcategories at 23andMe, dubbed “Recent Ancestor Locations,” are Syria, Jordan and Lebanon. But there is no Palestinian category. Asked why the company does not include Israel or the Palestinian territories as a place of recent ancestry, 23andMe replied: “23andMe Ancestry Composition matches ancestral DNA to regions based on their modern borders, and our research suggests it would be difficult to do so in this case.” (Note though that 23andMe does offer a transnational Ashkenazi Jewish category.)

For some customers, this is a reflection of the denial of Palestinian self-determination, and numerous petitions exist online demanding that 23andMe “recognize Palestine.” But what is Palestinian DNA anyway? Are self-identifying Palestinians, as a group, genetically distinct from their Lebanese, Syrian or Jordanian neighbors?

Scientific studies suggest that individuals from the Human Genome Diversity Project’s Palestinian, Druze and Bedouin samples share more genetic mutations with each other than they do with other groups. They also indicate that the three subpopulations can be differentiated from each other. Palestinians, the Bedouin and Druze can, by that criteria, be called a group, though others could fall within that group.

White baby Jesus

The modern human history of Palestine begins as early as Homo sapiens set foot outside of Africa. The oldest modern human bone, nearly 200,000 years old, was found two years ago near Mount Carmel in what is now northern Israel. This bone, however, does not belong to modern humans’ ancestors, but rather to a population that migrated out of Africa and later went extinct.

A Natufian burial site in Mount Carmel.Credit: Dani Nadal

This theory of multiple migrations out of Africa (not just via Sinai and Palestine but also via Bab Al-Mandeb and Arabia) culminated in the successful modern human exit from Africa around 60,000 years ago. It was only around 12,000 years ago that farming and permanent settlement began, apparently starting in the Levant, which unsurprisingly caused a population boom in the area.

These ancient occupants of the Levant indeed share a genetic link with modern Palestinians. A study by Marc Haber of England’s University of Birmingham compared the DNA of modern-day Middle Eastern populations to samples of ancient DNA found in archeological excavations. It found that modern Palestinians are genetically related to Levantine early farmers, who themselves descended from Natufian hunter-gatherers. Interestingly, modern Saudis and Yemenis have a stronger genetic link to these ancient Levantines than modern Palestinians do – apparently because these groups split off and isolated before the Levant experienced major ancient migration.

The ancient Levantines mixed with northern migrants from Anatolia as early as 10,000 years ago. They also mixed with migrants from Iran and the Caucasus, beginning 6,000 years ago – likely refugees who fled droughts in Mesopotamia.

And so, thousands of years ago, the people of the Levant were already a mix of earlier locals and peoples who came from elsewhere. These migrants also introduced phenotype variations like blue eyes (and so even if “Jesus was a Palestinian,” he may still have looked white). They are also credited with important cultural transformations, like the spread of Semitic languages.

Three Bedouin boys running with Palestinian flags in the Jordan Valley last month.Credit: Maya Alleruzzo,AP

Not even Roman

Despite numerous historical events that saw the region be occupied by peoples coming from elsewhere, as said, there is substantial genetic continuity in the Levant in the last 3,000 years. “Modern-day Levantines share much of their ancestry with the Bronze Age population,” says Almarri, citing two studies that analyzed human remains from multiple Canaanite sites.

Roughly speaking, Palestinians are 80 percent genetically similar to the Bronze Age inhabitants, and Palestinian Bedouin are even more so.

What about the other 20 percent of Palestinian DNA? An East African component was added to the region (on average 10 percent, in a south-to-north gradient, generally excluding the Druze population) and a European component (on average 8 percent, in a north-to-south gradient, generally excluding the Bedouin population).

According to another study by Haber, numerous cultural transitions have taken place in the Levant over the past two millennia, but these did not necessarily translate to major genetic transitions.

There were three genetic “pulses” that contributed to changes in Lebanese DNA since the Bronze Age. The first, which introduced European ancestry, took place 3,000 years ago during the so-called Bronze Age collapse of civilizations, when the so-called Sea Peoples attacked the Eastern Mediterranean.

The second, which introduced ancestry from central and south Asia, took place around 2,000 years ago during the rule of Alexander the Great, whose Macedonian forces conquered territories as far east as India. The third, which introduced (more) ancestry from Turkey and the Caucuses, took place 700 years ago, at the start of the Ottoman empire.

Interestingly, the study did not detect significant Roman or Crusader genetic contributions. Although the crusaders did mix to some extent with the local population, Haber found that any Crusader genetic traces were diluted over the generations.

Archaeologists digging in "Area K" of Megiddo, which provided most the samples from the site for a Canaanite DNA study.Credit: Ariel David

All happy families are alike

The main driver of genetic differentiation among Palestinians today is religion and culture. According to a recent survey, 99 percent of Palestinians marry from within their cultural and religious group. This study looked at the three main cultural groups (Muslims, Christians and Druze), but the practice of endogamy often goes further, driving people to marry from within the sect, clan or family.

Over time, endogamy stops gene flow between groups (mixture) and results in genetic differentiation (a similar mutation pattern). A famous example in European history is the maladaptive Habsburg chin. Another is genetic studies showing that modern Jews descending from Diaspora communities generally retained a strong Middle Eastern signal alongside variable contributions from their non-Jewish neighbors, Dr. Harry Ostrer of the Albert Einstein College of Medicine, New York, and Prof. Karl Skorecki of the Rambam Health Care Campus, Haifa, reported in 2013.

Haber observed that Christian, Muslims and Druze in Lebanon formed distinct genetic groups, and that one’s religious affiliation is a better predictor of DNA profile than one’s geography.

Furthermore, the date of creation of these genetic groups – meaning the approximate time at which they stopped mixing with others – was correlated with certain historical events. For Lebanese Christians, it correlated with Hellenic rule 2,000 years ago. For Druze, it correlated with the divergence of the Druze faith from mainstream Islam 1,000 years ago. And for Lebanese Muslims, interestingly, it was not timed with the spread of Islam 1,300 years ago but 700 years after the fact, around the creation of the Ottoman empire and a semi-autonomous state in Lebanon.

In fact, the expansion of Islam did the opposite than the emergence of other religions: It led to mixture with populations from across the Islamic empire, making Lebanese Muslims more similar to distant populations from Yemen to Morocco.

Archaeologists investigating the first unmistakably Philistine burial ground found in Israel, in Ashkelon.Credit: Philip Bohstrom

The contested hummus gene

Long before DNA ancestry kits became a popular Christmas gift and a multibillion-dollar industry, scientists and thinkers from various disciplines warned of the ethical dangers of DNA analysis. The results can unveil secret offspring, cause turmoil in families and shake one’s identity – and they can also be politicized.

In 2018, Israeli Prime Minister Benjamin Netanyahu tweeted an article about a DNA study which found that the Philistines – a group of coastal Canaanites that lived around Gaza – were found to have European-like ancestry. The study had concluded that a migration event had caused a European temporary genetic pulse among the Iron Age Philistines.

Netanyahu correctly explained that despite the semantic similarity, there is no direct relation between modern-day Palestinians and the ancient Philistines. However, in the same sentence, he incorrectly stated that Palestinians came from the Arabian Peninsula: “There’s no connection between the ancient Philistines & the modern Palestinians, whose ancestors came from the Arabian Peninsula to the Land of Israel thousands of years later. Palestinians’ connection to the Land of Israel is nothing compared to the 4,000-year connection that the Jewish people have with the land,” he wrote.

Almarri stresses the danger of using genetic science to fan the politics of hate and division. “The danger is conflating ancestry with identity, which are two different things,” he notes. Ancestry refers to one’s biological predecessors, while collective identity refers to one’s sense of belonging to a group. If anything, identity is in itself powerful enough, and it evolved as a survival mechanism long before any human ever set foot in Palestine.

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