In 2018, a team of geneticists at Stanford University published the results of a study that had taken them nearly two decades to complete. They had collected DNA samples from more than 8,000 people across every inhabited continent, from hunter-gatherers in the Kalahari Desert to fishermen on remote Pacific islands, farmers in the highlands of Peru, and herders in Central Mongolia. Their goal was to measure how much foreign DNA different populations carried and how much genetic continuity they had maintained with their ancient ancestors. When the rankings were released, they stunned even the researchers who had compiled them.
The populations most people assumed were genetically pure turned out to be among the most mixed on Earth, while the groups that scored highest on genetic continuity were not who anyone expected. The number one result came from a place most people could not find on a map. To understand the rankings, it is necessary to understand what the scientists were measuring. All humans alive today share a common ancestor who lived roughly 200,000 years ago in East Africa.
From that origin point, small groups moved outward. Some went north into the Levant and Europe, some pushed east through India and into Southeast Asia, some crossed the Bering Land Bridge into the Americas, and some sailed across open ocean to reach Australia and the Pacific Islands. As these groups separated, their DNA began to drift, accumulating random mutations shaped by climate, food sources, and disease. Over tens of thousands of years, populations developed distinct genetic signatures.
What the Stanford team measured was genetic continuity, how much of a modern population’s DNA can be traced back to the founding group of that region versus how much was introduced through migration, conquest, slavery, trade, and intermarriage. At the bottom of the ranking, Latin America scored as the most genetically blended landmass on Earth. The average person in Brazil, Colombia, Mexico, or the Caribbean carries DNA from three major continental sources: Indigenous American, European, and West African. In the Dominican Republic, the average citizen has genetic markers from all three in nearly equal proportions.
This was not a slow, natural process but the direct result of five centuries of forced contact, beginning with Spanish and Portuguese colonization in 1492 and continuing through the Atlantic slave trade, which brought roughly 12 million Africans to the Americas. What surprised the researchers was not the level of mixing but how much indigenous DNA had survived. Despite centuries of population collapse from disease, forced labor, and cultural erasure, the genetic signature of pre-Columbian peoples was still detectable in over 70 percent of the samples. Some regions of Mexico registered over 90 percent native ancestry.
The United States ranked nineteenth, its melting-pot identity confirmed by the data. African Americans on average carry around 24 percent European ancestry, while white Americans carry small but measurable amounts of Native American and African DNA. The surprise came at number eighteen, where the United Kingdom sat. Modern English people often imagine themselves as descendants of a single ancient stock, the original Britons or the Anglo-Saxons who arrived in the fifth century.
The DNA tells a different story. The average English person carries genetic contributions from at least seven distinct ancient populations, including pre-Celtic hunter-gatherers, Neolithic farmers from Anatolia, Bronze Age steppe migrants, Romans, Anglo-Saxons, Vikings, and Normans. The Anglo-Saxon migration, once described as a complete population replacement, actually contributed only about 40 percent of modern English DNA. The original Celtic population was not wiped out but absorbed.
The idea of a pure Anglo-Saxon bloodline is, genetically speaking, fiction. Spain ranked seventeenth, carrying heavy contributions from North African Berber populations as a legacy of nearly 800 years of Moorish rule, along with Roman, Visigothic, Phoenician, and Jewish genetic markers. Russia ranked sixteenth, its DNA showing contributions from Slavic, Finnic, Baltic, Mongol, Turkic, and Caucasian populations, evidence of centuries of expansion across Eurasia and the absorption of dozens of indigenous peoples. Numbers fifteen through twelve were all populations of the Indian subcontinent, which scored remarkably low on continuity not because of recent foreign mixing but because the region has been a meeting point for ancient populations for over 50,000 years.
Number eleven was Germany, whose genome proved far more mixed than its modern image suggests, containing Celtic, Slavic, Roman, Jewish, Polish, and Czech contributions. The genetic borders of Europe rarely match the political ones. A person from Eastern Germany often shares more DNA with someone from Western Poland than with someone from Western Germany. Number ten was Italy, one of the most genetically diverse populations in Europe.
A Sicilian and a Milanese can differ more from each other genetically than a Pole differs from a Greek, reflecting contributions from Greek, Phoenician, Etruscan, Latin, Germanic, Norman, Arab, and Byzantine populations. From this point upward, the ranking begins to show real genetic continuity. Number nine was Iran. Despite the Arab conquests, the Mongol invasions, and Turkic migrations, roughly 75 percent of the modern Iranian genome can be traced back to populations that lived on the Iranian Plateau over 4,000 years ago.
Number eight was Ireland, where geography played a major role in preserving a much higher percentage of original Celtic and pre-Celtic DNA. The Viking and Norman influences never overwhelmed the native population, and modern Irish DNA still strongly resembles the DNA found in 5,000-year-old burial sites across the island. Number seven was Finland, whose people carry genetic markers connecting them more closely to ancient Siberian populations than to their European neighbors. Centuries of isolation and a small founding population gave Finland one of the highest continuity scores in Europe, and geneticists use the Finnish population as a reference group for studying rare hereditary diseases.
Number six was the Basque people of northern Spain and southwestern France. Their language has no known relatives, and their DNA shows them to be one of the oldest continuous populations in Europe, with roots stretching back to the hunter-gatherers who lived on the continent before the agricultural revolution. While other European populations were reshaped by Bronze Age migrations from the steppe, the Basques remained largely untouched. Number five was the Sardinians, whose island acted as a genetic refuge for thousands of years.
Sardinian DNA is the closest living match to the DNA of the early Neolithic farmers who brought agriculture to Europe over 8,000 years ago. Number four was the Ainu of Japan, an indigenous people who carry ancient DNA linking them to the Jomon inhabitants of the Japanese archipelago before the arrival of rice-farming migrants from the Asian mainland. Fewer than 25,000 people identify as Ainu, but their genetic signature represents one of the oldest continuous human lineages in East Asia. Number three was the San people of Southern Africa.
Their DNA contains the deepest genetic roots of all living humans. Every other population on Earth branched off from a common ancestor more recently than the San did, meaning they sit closest to the trunk of the human family tree. Their hunter-gatherer culture preserves practices that may date back tens of thousands of years, and their genetic diversity within their own small population is greater than the genetic diversity of all non-African populations combined. Number two was the Yamato Japanese.
After the rice-farming Yayoi migrants arrived from the Asian mainland and mixed with the indigenous Jomon population around 2,500 years ago, the genetic composition of Japan stabilized and changed very little. Island geography and long periods of self-imposed isolation, especially during the Edo period from 1603 to 1868, kept foreign DNA out of the gene pool. And then came the result nobody predicted. The most genetically isolated human populations on the planet live on the Andaman Islands, a small archipelago in the Bay of Bengal.
The ancestors of the Andamanese, including the Sentinelese, the Jarawa, the Onge, and the Great Andamanese, were among the very first humans to leave Africa around 60,000 years ago. They migrated along the southern coastline of Asia, reached the Bay of Bengal, settled on the islands, and then they stopped. They never moved again and never encountered another human population in any sustained way for tens of thousands of years. The Andamanese are the closest living genetic match to the original modern humans who first populated Asia.
Their physical features, short stature, dark skin, and tightly curled hair, led anthropologists to assume they were related to African pygmies, but the DNA proved that assumption completely wrong. Their resemblance to certain African groups results from preserving traits that the original humans probably all shared, traits that other populations lost as they migrated into colder climates and adopted agricultural diets. The Sentinelese live on North Sentinel Island and have actively rejected all outside contact. They have fired arrows at every helicopter, boat, and person that has approached their shores.
In 2018, an American missionary named John Allen Chau attempted to land on the island and was killed within minutes. The Indian government has since prohibited all approach to the island, recognizing that the Sentinelese have no immunity to modern diseases and that any contact could destroy them entirely. The Sentinelese number perhaps 50 to 150 people, the Jarawa around 400, the Onge fewer than 120, and the Great Andamanese, who suffered the most from British colonial contact in the nineteenth century, fewer than 50. What shocked the scientists was not just that the Andamanese topped the ranking but what their DNA revealed about everyone else.
By comparing the Andamanese genome to every other population on the list, researchers were able to reconstruct the migration patterns of early modern humans with unprecedented precision. The study’s central truth was uncomfortable: there is no such thing as a pure race in the modern political sense. The populations at the top of the ranking are not pure because they are superior or untouched by history. They are pure because their ancestors were isolated by oceans, mountains, jungles, and deliberate choices to avoid the outside world.
Every other human population on Earth is the product of massive, constant mixing. The English are not Anglo-Saxon, the Spanish are not Visigothic, the Russians are not just Slavic, and the Italians are not descendants of Romans alone. Every population is a snapshot of a much longer journey, and that journey is still happening.