Lithuanian genetics study reveals new unique insights into our ancestry

Breaking the bread. Old Lithuanian tradition. @15min.lt
Breaking the bread. Old Lithuanian tradition. @15min.lt

The latest study on Lithuanian genetics traces the origin and ancestry of the Lithuanian population and reveals greatest influences on the Lithuanian genome. Scientists discovered genetic components belonging to ancestors from three different pre-historical periods and identified three hunter-gatherer groups as major influences in the formation of the main genetic component of the contemporary Lithuanian population.

The biological history of contemporary European populations is characterized by numerous migration waves, explains Prof. Kučinskas, one of the leading scientists in the latest study on Lithuanian genetics. When early Homo Sapiens began migrating to new lands and inhabiting new territories, they crossed paths and mixed with local settlers and other human populations, which still existed at the time. As living conditions improved, migration gradually subsided, and humans moved from a mobile hunter-gatherer lifestyle to a more settled way of life.

Studying the genomes of contemporary populations against ancient samples enables scientists to reconstruct this long history of human migration and admixture in a given region, thus yielding a more complete picture of the inhabitants’ ancestry. In the field of genetics, a genome refers to the complete set of a human’s DNA, including all of its genes.

When reconstructing the origin of the Lithuanian population, the scientists compared 399 Lithuanian genomes with 284 genomes from various historical periods, including a wide range of samples from West Eurasia and North Africa. Researchers studied genomes of Lithuanians who lived separately in the outlying areas of Lithuania, alongside two of their succeeding generations.

Earliest influences on Lithuanian genetics

Latest study findings point to the Lithuanian genetics distinctiveness and homogeneity of the Lithuanian population.

The study was led by Dr. Alina Urnikytė, Prof. Vaidutis Kučinskas, and Assoc. Prof. Alma Molytė from the Faculty of Medicine of Vilnius University, with contributions from colleagues in Spain and Estonia, and was recently published in the open-access scientific journal Scientific Reports.

Two cultural systems influenced the formation of the Baltic tribes, the pre-Indo-European and the Indo-European, explains Dr. Urnikytė.

Speaking of pre-Indo-European influences, which date back to the Paleolithic Era, scientists cite hunter-gatherer groups from Western Europe, the Scandinavian Peninsula and a somewhat smaller group of hunter-gatherers from Eastern Europe as the greatest ancestral influences on the formation of the main Lithuanian genetic component.

“The contemporary Lithuanian population is composed of a complex mixture of the former Baltic tribes, but our research shows that our genome has been formed by representatives of other distant countries or even continents. Researching the diversity of the DNA sequence, scientists found for the first time that the Lithuanian genome was formed by ancestors […] from three areas: the Uralic steppes, central Europe, and the Scandinavian peninsula,” says Prof. Kučinskas.

According to the study, the first settlement in contemporary Lithuanian territory was founded about 11,000 years ago in west Lithuania along the Baltic Sea, after the retreat of the last ice-sheet. The first inhabitants of contemporary Lithuanian land were related to hunter-gatherers from Western Europe. Scientists believe that early settlers favored the region due to suitable living conditions and “the presence of marine food resources,” the study reports.

What makes the Lithuanian population unique in this regard is the fact that the genome carries one of the largest proportions of western hunter-gatherers’ ancestry of all other Europeans populations to date, the scientists said.

“When we compared the present-day Lithuanian population with the ancient genomes of different historical periods, it turned out that Lithuanians are in most cases the most similar to the peoples of central Europe who lived there 5–8 thousand years ago. For example, today’s French are less similar to those who lived in France between 5 and 8 thousand years ago than current Lithuanians,” says Prof. Kučinskas.

Lithuanians’ pre-historical ancestry

The latest Lithuanian genetics research also revealed three main pre-historical sources shaping the genetic distinctiveness of present-day Lithuanians. These ancestral groups relate to the later Indo-European system, which dates back to the Neolithic Era around 4000-5000 years ago, Dr. Urnikytė explains.

“The main genetic component belongs to hunters-gatherers who lived earlier than the Neolithic, and the other two minor tribal components belong to early and intermediate Bronze Age pastoralists from the Uralic steppe and to late Neolithic Bronze Age Europeans,” the scientists report.

These study findings illustrate the complex biological history of the Lithuanian population, which was formed by admixing of different ancestor groups in different historical periods. It also illustrates that compared to other European populations Lithuanians managed to preserve their genetic distinctiveness over many centuries, despite unfavorable historical circumstances and fatal diseases that were prevalent in the ancient world at the time.

“We are an old population. We are unique,” emphasized Dr. Urnikytė.

Genetic differences between Aukštaičiai and Žemaičiai

According to Prof. Kučinskas, the latest genetic research allows to determine whether differences exist between the Lithuanian genome and the genome of other European and world nations, to better understand whether Lithuanians are closer to the peoples from the East or the North and to gain insight into the effects that the changing living conditions have had upon the evolution of Lithuanian genes.

The study also found slight yet statistically significant genetic differences between the inhabitants of villages in Žemaitija (lowland area) and Aukštaitija (highland area).

Scientists believe that partial genetic isolation of Lithuanians might account for these regional differences, claiming that geographical proximity and potential geographical obstacles at the time could be considered as determining factors in the formation of such genetic barriers.

The higher the hierarchical level of the population (village, locality, district), the fewer differences are found within the genome, the scientists claim.

“People living in different regions of the Lithuanian territory were relatively isolated due to dense forests and wetlands. Therefore, earlier significant genetic differences existed among Lithuanians from different geographic regions, but they have almost disappeared in the modern Lithuanian population,” said Dr. Urnikytė.

Other findings

The latest genetic research also included an analysis of positive natural selection signals. Scientists identified several natural selection signals for the Lithuanian population, including genes encoding different collagen chains (COL6A5, COL6A6) as well as genes responsible for light-skin pigmentation (SLC24A5, TYRP1). Other natural selection signals relate to diet (PNLIP, PNLIPRP3, and PPARD) and the immune response (BRD2, HLA-DOA, IL26 and IL22). The scientists cite specific pathogens and local Lithuanian diet among potential influences that might have affected these natural selection signals.

The full scientific article can be accessed here.

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