In search of explanations for a social breakdown Several lines of inquiry have been developed to address

this problem, but they do not cover all the variables that might have had a significant impact in the outcome of the process. In the present analysis, these variables will be divided into two sets: one regarding the factors considered external to the social relations (briefly mentioning recent published works), and the other corresponding to variables within social relations, where discussion will be more focused.

3.1 Outside the social relations

The impact of climatic changes in the late 3rd millennium BC in the collapse of social trajectories has been addressed for many European regions (Weiner 2014; Meller et al. 2015). In Iberia, the regional impact of the aridification 4.2 ka BP event (Mangy et al. 2009;

2013) has been considered in its possible relation with social changes observed in the archaeological record in several regions (Weinelt et al. 2015; Lillios et al. 2016;

Blanco-González et al. 2018; Schirrmacher et al. 2020).

In south Portugal, the data for climate during the 3rd millennium BC is still relatively scarce, although there is some evidence for a warming tendency along the millennium (Mateus, Queiroz 2000; Espino 2004;

Fletcher et al. 2007). But a direct relation between the episodes of significant climatic changes and social

dynamics is still difficult to establish at the moment in this region.

Recently, a curve for the demographic development between 5000-1000 BC in southwest Iberia was published, using available radiocarbon dates for settlements and burials as proxy (Blanco-González et al. 2018). A tendency for accelerated growth starts around 3500 BP and presents a first small break around 3000-2900 BC, and an even smaller one around 2800 BC (Figure 1). A peek of aridity was also detected at 2800 BC in the lower Guadiana basin (Fletcher et al. 2007).

These early 3rd-millennium events correspond to the transition from the Late Neolithic to the Chalcolithic in the region. In the Perdigões sequence (the best dated for the south of Portugal), this moment corresponds to a slight reduction in the area of the enclosures. But this break in the curve is rapidly surpassed, and the accelerated demographic growth continued until the middle of the 3rd millennium BC. It is then, previously to the climatic 4.2 ka BP event, that the graph shows the beginning of a decline which extends to the middle of the 2nd millennium BC.

It is possible that this early chronology for the inversion of the tendency of growth, preceding a final abrupt breakdown by the end of the millennium, may still

reflect the poor quality of the data (in terms of number of dated sites and of dates per site). A significant number of dates from the second half of the 3rd millennium BC recently obtained are not yet considered and recent data for Perdigões or Porto Torrão enclosures show intense chalcolithic activity during the third quarter of the 3rd millennium BC, suggesting that the breakdown was, in fact, in the beginning of the last quarter of the millennium. Even so, it does not seem to be related to the 4.2 ka BP event in terms of cause/effect. That is suggested by the recent paleoclimatic data indicating that the 4.2 ka BP event was not directly affecting the southwest (Schirrmacher et al. 2020: 12). In fact, this climatic occurrence is of large scale, and, as with all large-scale phenomena, it must have had diversified regional impacts according to local environmental and social conditions. In southwestern Iberia it seems to have been less effective and, at most, might have had an acceleration consequence for a change already in course. However, in certain areas, the impact of this event could have been particularly high, as recent studies in the Doñana and south Meseta seem to suggest (López-Sáez et al. 2017; 2018).

Another exogenous variable has been recently discussed: a migratory influx. DNA approaches have shown the flow into Iberia of Steppe-related ancestry Figure 1 - summed calibrated date range distributions for burials and settlements in the Southwest Iberia (adapted after

Blanco González et al. 2018, fig.18).

Figure 2 – Bell Beaker vessels with elongated profiles from the late 3^rd millennium BC. 1. Perdigões (South Portugal); 2. and 3. Fraga da Pena (Central-North Portugal).

during the Chalcolithic (Olalde et al. 2018). But the turnover detected in the Y-chromosome in the Bronze Age analysed individuals, with the almost complete substitution of the Chalcolithic lineages, suggests a significant contribution of migrations (Olalde et al. 2019). It is too soon, however, to evaluate the

dimension and impact of these influxes in the social change observed by the end of the 3rd millennium BC.

This information needs to be carefully integrated with archaeological and anthropological data and theory to try to understand the role of population influxes in the process. For the moment, and for southern Portugal,

we can only say that the material assemblages of the Early Bronze Age do not show a significant number of items that can clearly be related to continental Europe within a context of an eventual massive and sudden population movement. However, some punctual elements of material culture can be stylistically related to continental influences. That is the case of a bell beaker from the Perdigões enclosure, dated from the end of the 3rd millennium BC, that presents a high profile and is decorated with rows of circular denticulated stamps (Figure 2: 1). Similar high profiles are also known in the walled enclosure of Fraga da Pena (central Portugal), also dated from the last century of the 3rd millennium BC (Figure 2: 2). But these are just scattered elements within a scenario characterised mainly by local and regional traditions.

Another hypothesis involving the movement of people was suggested to explain the demographic decay observed in the southwest. As this decay is roughly coincident with an opposite tendency observed in the southeast quadrant of Iberia, a possible west to east displacement of people was suggested (Lillios et al.

2016; Blanco González et al. 2018), although the existing isotopic studies amongst some Argaric populations (Aranda Jiménez et al. 2015) have not yet identified these possible migrants. Nevertheless, if an eventual migration could help to explain a demographic reduction in the southwest, it provides no explanation for the observed structural change in many other dimensions of the social system.

3.2 Inside social relations

Social dynamics are systemic and dialectical. Every circumstance in the development of a system may result in more or less profound changes or even collapse.

The outcome, however, is forged in the interactions between the different elements within the system and in their external relations. In other words, the outcomes are neither inherent, linear, nor predictable. They are related to the contingencies of those interactions and to the relations they design. That is why they are not generalised, allowing diversified solutions and trajectories in time and space.

In the south of Portugal, as in the whole Andalusia (Gilman 2013; García Sanjuán 2017), and other regions, such as the Portuguese Estremadura (Jorge 1999;

Sousa 2010) or central Iberia (Diáz-del Río 2003; Ríos 2011; Schmitt 2017), the accelerated social trajectory developed since the end of the 4th millennium BC brought the region to levels of complexity previously unknown and with no parallel in central-north Portugal. The reasons for that asymmetry are not yet fully understood. We may think in terms of processes of resistance to social change, able to generate slower rhythms of transformation and induce distinctive

trajectories. Studies of social resistance to change, however, are rare in Portuguese archaeology. Successful social conservatism tends to be interpreted not as such, but as minor expressions of trajectories of social complexification, adopting and adapting templates developed for other scenarios.

Nevertheless, southern Portugal was one of those areas that suffered an accelerated and intense transformation.

The first two centuries of the second half of the 4th millennium BC marked the take-off of that trajectory (Valera 2018), after which there is an acceleration of the historical process of social complexification that will characterise the region in continuity between 3300-2300/2200 BC. Amongst the multiplicity of variables of the systemic social relations developed during this period, four were selected to be discussed here.

First, the velocity of change that was rapidly brought about (metaphorically associated to an express train of the ‘West’ in the title of this chapter). Second, the participation in growing interaction networks of transregional scale, with significant circulation of people and exotic materials. Third, the development of a strong need for forms of ideological expression progressively more monumental and diversified, and consumers of high quantities of labour and logistics.

Finally, the development of practices of social emulation and practices of wealth squandering, with the double and contradictory social role of promoting social inequality at the same time as they function to control it.

4. The internal variables selected for discussion