4,500-year-old Tomb in France Unveils the Origins of the "European Genome"

A groundbreaking study utilizing DNA analysis has shed light on the ancient intermingling of human populations and its impact on the formation of the "European genome." Delving into the genomes of individuals laid to rest in a collective tomb near Troyes, Bréviandes-les-Pointes in France, researchers have made fascinating discoveries, as outlined in a recent publication in Science Advances. Their findings carry immense implications.

The human genome contains the entirety of genetic information encoded within our DNA, offering insights into our ancestral history. Over a span of 40,000 years, the present-day European genome gradually took shape through migratory movements and the subsequent intermingling of diverse populations. Thus, it encompasses the intricate genetic heritage inherited from hunter-gatherer groups who inhabited Europe until the arrival of Anatolian and Aegean populations roughly 8,000 years ago. These later arrivals, beneficiaries of agricultural advancements and animal domestication in the Fertile Crescent, interbred with the local hunter-gatherers, substantially contributing to the genetic makeup of contemporary Europeans.

Notably, the most recent gene pool contributor emerged during the late Neolithic period, around 5,000 to 4,000 years ago. Nomadic groups hailing from the Pontic steppes in the vicinity of the Black Sea embarked on a migratory influx, carrying an additional genomic component that has persevered throughout following millennia in Europeans.

Deciphering ancient individuals' genetic information presents a substantial challenge owing to the limited and fragmented remains available for analysis. Although modern technology allows routine genetic sequencing, retrieving meaningful data from long-gone ancestors demands careful methodologies due to the scarcity and fragmented nature of preserved DNA.

Taking on this daunting task, the research team at Institut Jacques Monod achieved optimization of methods to produce reliable results. Employing state-of-the-art bioinformatics and statistical analysis, they examined ancient genomes.

Insights from a Collective Tomb

Examining the genomes of seven specific individuals buried in the Bréviandes tomb and substantiating their findings with bone morphology analyses conducted by Inrap anthropologists, researchers uncovered astounding revelations. The tomb contained the remains of various individuals:

- A woman, aged over 60 at the time of death- Her son, an adult man aged between 20 and 39- Her grandson, aged approximately 4 to 8- The grandson's mother, aged 20 to 39- A young woman aged 20 to 39- The young woman's newborn baby- A child, aged between 6 and 10

Interestingly, the three last individuals lacked any biological relation to the others found in the tomb. Notably, the last child did not share biological ties with any of the tomb's occupants. As a result, it is discernible that this burial site represents not a single family's resting place. However, all the female individuals carried a hereditary element characteristic of populations from southern France and southwestern Europe. The common origins shared by these women, distinct from the area containing the tomb, provide an explanation for their collective burial alongside their offspring.

Further analysis led to the intriguing discovery that the adult man's genome comprised genetic contributions from both the French Neolithic—traced back to his mother—and nomadic steppe populations north of the Black Sea, attributed to his father. Roughly 5,000 years ago, these nomads migrated to central Europe where they interbred with local Neolithic populations before continuing eastward, northward, and northwestward. Hence, within this set of individuals interred in the tomb, we can observe, in almost real-time, the infusion of steppe nomad genome into the Neolithic population of the region.

Remarkably, this unique scenario, hitherto undescribed, enabled the reconstruction of the absent father's genome using the genomic signature manifested in the remaining bones. The revealed genetic markers suggest a northwestern European origin. Intriguingly, similar results were obtained from the examination of another individual buried in the Aisne valley—also carrying steppe ancestry—from the same period. It can be inferred that these two men potentially belonged to the same populace.

Dual Waves of Intermixing

By expanding the study to incorporate previously analyzed ancient genomes from different European localities, the research team obtained valuable insights into the migrations of steppe peoples. Their findings propose two major waves of interbreeding that occurred during the third millennium BCE. The initial wave involved intermingling between steppe nomads and Neolithic farmers associated with the distinctive, globular-shaped ceramics featuring two to four handles. This significant fusion most probably transpired in Eastern and Central Europe amidst 4,900 years ago.

The descendants of this intermingling fostered an entirely new archaeological culture known as the Corded Ware culture—an amalgamation of elements from the globular amphora culture and corresponding steppe cultures. It was characterized by the individual burial of the deceased and the creation of cord-ornamented pottery, from which the culture derives its name. The Corded Ware culture proliferated eastward and northward across Europe with members of mixed Neolithic-Steppe lineage mostly reproducing within their own ranks rather than merging with native farming populations.

Another wave of extensive genetic intermingling with indigenous populations emerged approximately 300 to 400 later, circa 4,550 years ago, in western Europe. In both interbreeding instances, the migrants predominantly consisted of men intermarrying with native women. It is this second wave that the Bréviandes-les-Pointes tomb unravels for the researchers.

Notably, juxtaposing the genetic sequencing with the burial analysis of an adult male in Saint-Martin-la-Garenne, located east of Paris, revealed the profound impact of such interminglings on the transformation of the European genome. This individual underwent burial rituals typical of the Bell-Beaker culture, distinguishable by the presence of bell-shaped pottery discovered in numerous tombs. Initially developing in the west of Europe—stretching from the southwest to the northwest—the Bell-Beaker culture eventually permeated throughout Europe and North Africa. The adult male burial included a wristguard of shale, characteristic of the Bell-Beaker culture and indicative of his elevated social standing. His genetic makeup exhibits steppe ancestry, with the inference that his mother held an even higher proportion of steppe DNA. This suggests that matrimonial networks formed between Bell-Beaker populations and groups from other regions characterized by greater steppe ancestry. By the end of the Bell-Beaker period around 2000 BCE, a majority of males analyzed carried the Y chromosome of the steppe peoples—an ancestral trait that still holds considerable prevalence among French males today.

Embracing the Transformative Encounters

Conclusively, the two significant phases of hybridization between steppe migrant groups and indigenous populations coincided with the emergence of the Corded Ware and Bell-Beaker cultures. The latter, in particular, marked the existence of the first pan-European culture. These encounters and subsequent interminglings have culminated in the distinct genome observed in a substantial proportion of contemporary Europeans.