A documentary aired on Spain’s national television this month has made headlines around the world for its revolutionary claim that Christopher Columbus was a Sephardic Jew from the Iberian Peninsula, contrary to the widely accepted theory that he hailed from Genoa in Italy.

A team of forensic experts led by the University of Granada used DNA analysis to investigate the background of the 15th-century explorer in a bid to lay to rest a longstanding debate on the origins of the man whose expeditions opened the way for Europeans to colonise the Americas.

While the scientific method behind the findings has yet to be made public, the history-changing claims contained in the documentary Columbus DNA: His True Origins have brought to the forefront how DNA may hold the key to the unsolved mysteries of the past.

How does ‘archaeogenetics’ work?

Archaeogenetics is the study of ancient DNA, or DNA that is more than 70 years old.

Rodrigo Barquera, a researcher in archeogenetics at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, explained that genetic material is collected from human archaeological samples and then purified and sequenced before being examined.

“The more time has passed since the person’s death, the harder it is to find genetic material,” Barquera told Al Jazeera, adding that the conditions in which the remains are preserved also play a crucial role.

The analysis can reveal information about the sex and ancestry of the person as well as any diseases the person may have suffered from. It can also determine which populations are more closely related to the sample and therefore suggest a geographical area of provenance.

What cannot be inferred are cultural elements such as nationality or religion, or precise ethnicity.

What has been discovered about Christopher Columbus?

The documentary broadcast on Spain’s National Day claimed the findings – which have not yet been peer-reviewed – show Columbus was of “western Mediterranean” origin, suggesting a genetic similarity with the people who inhabited the Iberian Peninsula, where modern-day Spain is located.

This conclusion contradicts the widely held view that Columbus was from the Republic of Genoa, a port city located in northern Italy.

The documentary also suggested Columbus was a Sephardic Jew, a specific Jewish diaspora population associated with the Iberian Peninsula.

However, as Barquera put it, “there is no gene for Jewishness” as cultural traits such as religion are not contained in a person’s DNA.

The team at the University of Granada, which led the research on Columbus, has not detailed the scientific method used. This will be revealed when the findings are officially published in November.

Barquera, who has no connection to the project, speculated, however, that researchers may have found a similarity to some traits shared by the Jewish population.

While Jewishness is not a genetic but cultural trait, they may have had a “cluster” – or a group – of Jewish people with whom to compare the genetic information.

Even then, he said: “Tests are usually done with several human groups and all of them would show some statistical attraction.” Therefore it would be unscientific to pinpoint a single affiliation rather than multiple probable ones.

Why was the study of Columbus’s remains undertaken and why does it matter?

The provenance of the man who made the European “discovery” of the Americas in 1492 has long been debated.

Francesc Albardaner, an architect and decades-long researcher of Columbus who features in the documentary, has been one of the proponents of a different version of history to the “Genoa theory” that textbooks have stated for centuries.

“Columbus was a Catalan and the son of a man from the Republic of Genoa and a Jewish woman from Valentia,” Albardaner told Al Jazeera, adding that his conclusions match those presented by the documentary.

Albardaner claims Columbus preferred to present himself using his paternal affiliation due to the scorn and persecution faced by the Jews at the time.

He added that the proponents of the “Genoa theory” have come up against the fact that documents produced under the rule of Ferdinand of Aragon did not state Columbus’s place of origin, as it was the case at the time.

“When talking about foreigners, the Kingdom of Castile explicitly said where they were from,” Albardaner said, citing as a case in point documents that registered Italian explorer Giovanni Caboto as Venetian.

“In the case of Columbus, they only state that he is a foreigner,” Albardaner said, adding that this anomaly had never been fully explained.

The theory that sees Columbus born as a Jew under the reign of Ferdinand would also explain why he was able to become one of the highest civil servants within the kingdom, a position that would have been unlikely for a foreigner to hold.

Albardaner added that establishing the historical truth about Columbus’s early life was consequential. “One little mistake can lead to a whole series of wrong assumptions,” he said, leading historians adrift when researching his early years and activity.

For instance, in a research paper, Albardaner detailed how Columbus’s claim that he had visited “all the East and the West” before 1470 – contained in a letter written in 1501 – has been dismissed, especially by Italian scholars, as invention and vanity.

Albardaner argued that placing Columbus’s life under Ferdinand’s rule would give historical credibility to his naval service in the Mediterranean and establish that he had, in fact, begun sailing in 1461 or earlier.

Which other famous cases of genealogy discoveries have there been?

Researchers are using DNA to uncover the many mysteries that still surround the history of humanity.

Several studies have focused on remnants of the Neanderthals, distant ancestral relations to modern humans, to reconstruct how close their relationship to our species was and what their social organisation looked like.

The fossil of a six-year-old child retrieved at the Cova Negra archaeological site in the province of Valencia, Spain, excavated in 1989 and examined earlier this year, even hinted at signs of compassion among Neanderthals.

Nicknamed “Tina”, the child is the earliest-known evidence of a person with Down syndrome and was also afflicted by several illnesses. Researchers at the University of Alcala in Spain concluded that for the child to have survived at least six years, the group must have continuously assisted the mother with her daily tasks, pointing to compassion.

Barquera and his team in Leipzig also worked on the remnants of another historical figure, the German composer and pianist Ludwig van Beethoven. “We could reconstruct part of the genealogy and because the sample was really good, we could even do some testing for health-related issues and confirm that he had hepatitis B,” Barquera said.

“In the past, we could only rely on what was written, but now [thanks to these technologies] we can confirm or exclude some assumptions,” he added.

“In some cases, we might help draw a better picture of specific historical events.”