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- Hunter-gatherer genetic persistence at the onset of megalithism in western Iberia: New mitochondrial evidence from Mesolithic and Neolithic necropolises in central-southern PortugalPublication . Carvalho, AF; Fernández-Domínguez, Eva; Arroyo-Pardo, Eduardo; Robinson, Catherine; Luis Cardoso, João; Zilhão, João; Gomes, Mário VarelaDespite its strategic importance at the furthermost edge of the Neolithic expansion in Europe, archaeogenetic data from Mesolithic and Neolithic human remains from Portugal are still very limited. Here we present ancient mtDNA evidence (mostly unpublished) to fill the gap and discuss the pattern of "genetic resurgence" of huntergatherer (Mesolithic) ancestry, widely reported elsewhere in Europe, among the first megalith builders (Middle Neolithic) of western Iberia.A total of 11 Mesolithic and Neolithic necropolises located in the central and southern regions of Portugal dated to ca. 6200-3000 BC were studied. These sites comprise all Mesolithic-Neolithic cultural stages and include several funerary architectures and spaces. Reproducible mtDNA HVRI haplotypes were obtained from 23 individuals from six different archaeological sites spread across a >3000-year transect, from the Late Mesolithic to the Late Neolithic.Our results support a three-stage explanatory demographic and populational model: i) local hunter-gatherer populations constituted a highly homogeneous genetic pool; ii) the first farming practices were introduced by human groups carrying new, extraneous haplogroups and exhibiting the signature of admixture events occurring at the time of first contact with local hunter-gatherers; iii) the genetic pattern detected among the megalithbuilding populations, showing hunter-gatherer along with farming ancestry, may be explained by the segmentary principles, and attendant endogamic practices, that structured Neolithic societies.
- Multi-isotope approaches to the Neolithic cemetery-cave of Bom Santo (Lisbon): new data and comparisons with fourth millennium BC populations from central-southern PortugalPublication . Carvalho, AF; Gonçalves, David; Bonilla, Marta Diaz-Zorita; João Valente, MariaPrevious multi-isotopic research on the human remains of the Neolithic cave-cemetery of Bom Santo (Lisbon, Portuguese Estremadura) led to the conclusion that this fourth millennium BC population was very heterogeneous at several levels. Two in particular were subsistence habits and mobility: although consumption of terrestrial foods was the norm, aquatic food sources totalling > 20% of overall diets were detected in 60% of the population, and, surprisingly, 79% of the individuals were classed as non-local, having lived most of their life in geologically older regions. These figures were however obtained on a sample of 15 individuals. Further isotopic analyses have enlarged the original sample to 35 individuals (i.e., half of the exhumed population) and were also employed in the study of the coeval cave-cemeteries of Barrao and Mureta. This has permitted a sounder depiction of past behaviours, with a structural difference being observed at both levels between Bom Santo and the latter sites: at the former cave, 70% of the population consumed > 20% of aquatic foods and 34% were non-local (23% from outside Estremadura), whereas the latter were all local and showed no signals of aquatic diets. Comparison with other fourth millennium BC populations in central-southern Portugal suggests a model where the exploitation of locally available aquatic/marine food sources was not mandatory but optional and that human mobility represented an important socio-economic behavioural feature of these (presumably) segmentary societies. How both aspects related to the then-emerging megalithic phenomenon is a question that should be investigated in future research.
- Population dynamics during the Neolithic transition and the onset of megalithism in Portugal according to summed probability distribution of radiocarbon determinationsPublication . Pardo-Gordo, Salvador; Carvalho, AFAs field data accumulates, the study of Neolithic Portugal has been receiving increasing attention recently, from material culture and subsistence to ideology. However, little is known about population dynamics. In this paper, we use a judicious selection of radiocarbon determinations to evaluate demographic phenomena within the 9.500-5.000 cal BP range (thus, starting in the Late Mesolithic) making use of "summed probability distribution" analysis. In greater Portugal, results show a negative deviation (i.e. demographic decrease) at 6.400-6.300 cal BP and a positive deviation (i.e. demographic increase) at 5.350-4.950 cal BP. These can be explained, respectively, by the impact of farming about one millennium after its introduction (confirming the "Neolithic demographic transition" model) and by the full establishment of the "secondary products revolution" in the Late Neolithic. However, individual analyses of the northern and southern halves of the country-i.e. using the Mondego river valley as an ecological-geographical divide-show rather contrasting trajectories, with scarce Mesolithic populations and a demographic increase in the megalithism in the North, whereas in the South a demographic crisis occurred at the onset of megalithism (which remains to be fully explained) being followed in the Late Neolithic by a sharp demographic increase. Further summed probability distribution analyses of radiocarbon determinations, particularly if combined with other populational proxies, will be able in the future to detect other demographic events taking place in space and time.