**1. Introduction**

#### **1.1. State of the art**

Ancient mitochondrial DNA (mtDNA) provides important insights into the movement and spread of human populations. In particular, European populations exhibit some remarkable changes after the end of the last glacial maximum (after 20,000 YBP). The changes in the early postglacial period are thought to be the result of the arrival of new human population groups to Europe [1]. These new populations brought to Europe new mitochondrial DNAs that caused a change in the frequency of the indigenous mtDNA lineages. By reconstructing

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

the variability of the mtDNA of past populations, it is possible to infer population movements that shaped the current genetic variability of our species.

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—

Paleogenetics of Northern Iberian from Neolithic to Chalcolithic Time

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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].

Europe in the Chalcolithic period accompanied by the BB culture [16].

landscape among Chalcolithic European groups (with and without BBC culture).

**2. Material and methods**

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

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

In this chapter, we have analyzed the human remains from El Aramo Mine discovered in 1888, a mine located in the Asturias region in the Cantabrian fringe of the Iberian Peninsula [41].

Atapuerca, Spain—dated to more than 400,000 years BP) [25–31].

One of the most studied population movements is Neolithization, the transition from a nomadic hunter-gatherer to an agro-pastoralist lifestyle. The debate on the mechanisms of the Neolithic transition has been framed within a dichotomy based on either a demic (DD) or a cultural diffusion (CD). According to the DD model, the migrating people bringing new knowledge experienced some gene flow with the local hunter-gatherer groups. On the other hand, the CD model postulates that the Neolithic transition was mediated mainly through the transmission of the agro-pastoralist system without substantial movement of people [2].

However, several DNA studies on different ancient European populations indicated a more complex pattern for the Neolithic transition. Unlike the initial proposal based on classical genetic markers that suggested a major migration wave [3], further studies have shown that the Neolithization process varied in different regions, occurring along several different routes into and across Europe, and having a different genetic impact on the various regions and at various times [4–17].

The mtDNA frequency distribution observed in hunter-gatherers and farmers from Europe provides support for a random dispersion model for Neolithic farmers, with different impacts on the various geographic regions (Central Europe, Mediterranean Europe, and the Cantabrian fringe) [9].

The transition from the Neolithic to the Chalcolithic period in Europe has been debated. Previous mitochondrial DNA analyses on ancient Europeans have suggested that the current distribution of haplogroup H was modeled by the expansion of the Bell Beaker culture (BBC) out of Iberia during the Chalcolithic period. In addition, it has been suggested that these groups with Bell Beaker (BB) culture in Central Europe represented a population movement from the Iberian Peninsula [16]. However, according to the mtDNA variability in Chalcolithic groups from the Cantabrian fringe of Iberia, no genetic relationships have been detected between these Iberian and Central European groups [17]. This suggestion has been confirmed by the recent study [18] about the Beaker phenomenon and genomic data of Europe.
