Iberian peninsula stayed a Steppe ahead of Eastern immigration

27 Jul 2017

Image: yoshi0511/Shutterstock

In contrast to most of Europe, Iberia experienced little in the way of population influx from the Steppe, according to new research from Trinity College Dublin.

The latest in what is a growing line of previous cultures to have their DNA sequenced, inhabitants of what is today’s Spain and Portugal have received the treatment.

The prodigious Prof Daniel Bradley has partnered with Prof Rui Martiniano to look into genetic changes that, surprisingly, don’t match up with the rest of Europe.

Future Human

The researchers sequenced the genomes of 14 individuals who lived in Portugal during the Neolithic (4200-3500 BCE) and Bronze Ages (1740-1430 BCE) and compared them to other ancient and modern genomes.

In between these eras, masses of people poured into Western Europe from the Steppe regions of Asia and Eastern Europe.

Iberia untroubled

In contrast to other parts of Europe, the duo detected only subtle genetic changes between the eras in Iberia, which presumably resulted from small-scale migration.

Martiniano said: “It was surprising to observe such a striking Y chromosome discontinuity between the Neolithic and the Bronze Age, such as would be consistent with a predominantly male-mediated genetic influx.”

The findings match up to some more cultural curiosities, such as why Iberia harbours a pre-Indo-European language, called Euskera, spoken in the Basque region along the border of Spain and France.

North of that border, Indo-European languages, thought to have evolved from the Steppe migration, took hold.

“Unlike further north, a mix of earlier tongues and Indo-European languages persist until the dawn of Iberian history –  a pattern that resonates with the real but limited influx of migrants around the Bronze Age,” said Bradley.

Archaeological remains of an individual from the Portuguese site of Hipogeu de Monte Canelas I. Image: Rui Parreira

Archaeological remains of an individual from the Portuguese site of Hipogeu de Monte Canelas I. Image: Prof Rui Parreira

Genome sequencing

The study is published in Plos, and is one of many that Bradley has his fingerprints on, with his innovative genome sequencing process keeping him ahead of the game.

This is helped, in part, to the preservation of the human ear years after death, and long after many thought any useable tissue remained on a skeleton.

“A few years ago, we found the best bone to preserve human DNA was in the ear,” he told me last year, with other leading-edge scientists also realising this holy grail of discovery.

Bradley has collaborated on fascinating genomic projects such as the 2015 discovery of a new genetic strand of an ancient human, a European hunter-gatherer descendant.

Genomes discovered in Georgian caves revealed remains from two humans who lived in the Caucasus thousands of years apart, 13,300 and 9,700 years ago, respectively.

Among the genomes was the first ever sequencing of one from the late Upper Palaeolithic period, with the results published in Nature Communications.

Elsewhere, 80 skeletons discovered in York a decade ago were put through Bradley’s genome sequencing processes last year. The results showed a multi-ethnic band of gladiators, hinting at a rich, diverse culture in the UK as recently as a couple of thousand years ago.

Bradley and his colleagues also sequenced the genomes of ancient Irish farmers, discovering that haemochromatosis (known as the ‘Celtic curse’) was inherited by people from the Pontic Steppe 4,000 years ago.

Gordon Hunt was a journalist with Silicon Republic