**1.2. Paleogenetics and paleogenomics**

*Paleogenetics* consists of the recovery and analysis of DNA obtained from the remains of individuals from the past, through polymerase chain reaction (PCR) and Sanger sequencing (ancient DNA—aDNA). These techniques are mainly applied in the analysis of mtDNA and fragments of nuclear DNA [9, 10, 19–22]. Since 2005, with the development of next-generation sequencing (NGS) technologies, it has been possible to retrieve also genomic data (*Paleogenomics*) from prehistoric European humans [23, 24]. This technology has allowed overcoming the apparently insurmountable difficulties associated with the deficient preservation of genetic material and the contamination of ancient DNA samples by modern DNA. NGS allows sequencing all those molecules that are present in DNA extracts (intact, contaminant, and damaged molecules, DNA from other organisms, etc.). The subsequent bioinformatic analysis allows discriminating endogenous sequences from exogenous sequences.

Massive sequencing has allowed important achievements in the field of human evolution, such as the "Neanderthal Genome" project, the discovery of new species (e.g., denisovans), and the recovery of the genome of very ancient humans (remains of La Sima de los Huesos— Atapuerca, Spain—dated to more than 400,000 years BP) [25–31].

The first paleogenomic studies about modern humans was the 7x coverage genome of the exceptionally well-preserved Tyrolean Ice man, Ötzi, dated to about 5300 years BP [32]. Currently, there are complete genomes from over 90 humans that inhabited Eurasia between 50,000 and 5000 years BP (hunter-gatherers and Neolithic farmers), shedding light on the migratory movements that shaped the genetic variability of modern humans and validating hypotheses proposed from the inference of modern genomes or partial sequences of these individuals [11, 13–15, 23, 24, 33–39]. These paleogenomic studies will enlarge the possibilities of selective and demographic analyses of the European prehistoric populations. The genomic data from European hunter-gatherers and farmers show that there is no evidence that the first modern humans in Europe (~45,000–37,000 years ago) contributed to the genetic makeup of current Europeans; these data rather suggest that individuals between ~37,000 and ~14,000 years descended from a single-founder population that is part of the ancestry of today's Europeans. During the period of greatest warming after ~14,000 years ago, a genetic component related to the inhabitants of the Middle East region became widespread in Europe. These results document how population rotation and migration have been recurring themes of European prehistory [23].

Recently, 400 European individuals ranging from the Neolithic period to the Bronze Age were analyzed using paleogenomic techniques, including 226 individuals associated to Beaker complex artifacts [18]. Limited genetic affinity between BBC-associated individuals from the Iberian Peninsula and Central Europe was observed, and thus the authors excluded migration as an important mechanism of spread between these regions [18]. This result rejects the hypothesis of the migratory movement of humans from the Iberian Peninsula to Central Europe in the Chalcolithic period accompanied by the BB culture [16].

In the debate about the biological influence of the dispersion of the Beaker culture in Europe, we have analyzed the mtDNA of remains recovered in El Aramo Mine in Asturias (Cantabrian fringe) from the Late Chalcolithic period that were not accompanied by BB cultural artifacts [41]. This human group is contemporaneous to other Iberian Chalcolithic populations both without Beaker complex artifacts associated and with Beaker culture associated. Sites without BBC associated are those of Longar and San Jaun Ante Portam Latinam (SJAPL) in the Basque Country [9]. Contemporaneous sites with Beaker complex culture associated are the central and southern Iberian and central European groups published by [18, 40]. The aim of this study is to contribute new mtDNA data variability of the Chalcolithic site from El Aramo Mine (Asturias) and to determine whether there is either a common genetic signal or a heterogeneous genetic landscape among Chalcolithic European groups (with and without BBC culture).
