Ancient DNA from an Early Neolithic Iberian
population supports a pioneer colonization by first

P. UTRILLA,§ M. EDO, – M . MOLIST , * * R . RASTEIRO , †† L . CHIKHI ††‡‡§§ and E ARROYO-PARDO *

*Laboratorio de Gene´tica Forense y Gene´tica de Poblaciones, Facultad de Medicina, Pabello´n 7, 4ª Planta, Universidad Complutense de Madrid, Avenida Complutense s ⁄ n, 28040 Madrid, Spain, †Instituto de Arqueologia e Paleocieˆncias, Universidade do Algarve, 8005-139 Faro, Portugal, ‡UMR 5199 PACEA, Laboratoire d’Anthropologie Des Populations Passe´es et Pre´sentes, Universite´ Bordeaux 1, 33405 Talence cedex, France, §Departamento de Ciencias de la Antigu¨ edad, Universidad de Zaragoza, 50009 Zaragoza, Spain, –Departament de Prehisto`ria, Histo`ria Antiga i Arqueologia, Universitat de Barcelona, 08032 Barcelona, Spain, **Departamento de Prehistoria, Universitat Auto`noma de Barcelona, 08193 Bellaterra, Spain, ††Instituto Gulbenkian de Cieˆncia, P-2780-156 Oeiras, Portugal, ‡‡CNRS, Universite´ Paul Sabatier, ENFA; UMR 5174 EDB (Laboratoire Evolution & Diversite´ Biologique); 118 route de Narbonne, F-31062 Toulouse, France, §§Universite´ de Toulouse; UMR 5174 EDB, F-31062 Toulouse, France

The Neolithic transition has been widely debated particularly regarding the extent to
which this revolution implied a demographic expansion from the Near East. We
attempted to shed some light on this process in northeastern Iberia by combining ancient
DNA (aDNA) data from Early Neolithic settlers and published DNA data from Middle
Neolithic and modern samples from the same region. We successfully extracted and
amplified mitochondrial DNA from 13 human specimens, found at three archaeological
sites dated back to the Cardial culture in the Early Neolithic (Can Sadurnı´ and Chaves)
and to the Late Early Neolithic (Sant Pau del Camp). We found that haplogroups with a
low frequency in modern populations—N* and X1—are found at higher frequencies in
our Early Neolithic population (31% ). Genetic differentiation between Early and
Middle Neolithic populations was significant (FST 0.13, P <10)5), suggesting that
genetic drift played an important role at this time. To improve our understanding of the
Neolithic demographic processes, we used a Bayesian coalescence-based simulation
approach to identify the most likely of three demographic scenarios that might explain
the genetic data. The three scenarios were chosen to reflect archaeological knowledge and
previous genetic studies using similar inferential approaches. We found that models that
ignore population structure, as previously used in aDNA studies, are unlikely to explain
the data. Our results are compatible with a pioneer colonization of northeastern Iberia at
the Early Neolithic characterized by the arrival of small genetically distinctive groups,
showing cultural and genetic connections with the Near East.

Keywords: ancient DNA, Iberian Peninsula, mitochondrial DNA, Neolithic

Received 8 July 2011; revision received 5 October 2011; accepted 11 October 2011