Size changes in wild and domestic pig populations between 10,000 and 800 cal. BC in the Iberian Peninsula: Evaluation of natural versus social impacts in animal populations during the first domestication stages

Abstract

In the early-Holocene, animal domestication processes entailed important changes to the subsistence strategies of Neolithic populations. Among the first domestic species, pigs played a key role as they soon came to be one of the main sources of meat. Several methodological approaches have been followed in archaeology to differentiate between wild and domestic forms in the faunal remains found at early Neolithic sites. Among these, biometry is essential. The biometric analysis applied to a significant sample of Sus domesticus and Sus scrofa remains from 53 sites in the Iberian Peninsula dated between 10,000 and 800 cal. BC reveals differential dynamics between the wild and domestic forms resulting from changes in the climate during that time and the increasingly systematic selective pressure of husbandry. Whereas the wild animals increased in size, the inverse tendency is documented in the domestic population, which gradually decreased in size after the early Neolithic. The point of greatest divergence is seen in the Bronze Age. Significant differences are also documented in different geographic areas, which corroborates the influence of climate on the physical characteristics of wild populations. The range of variability in each population also differs chronologically as it is relatively greater in the Neolithic, which may be connected with the existence of different ways of adopting and breeding domestic pig among the first Neolithic communities, some of which may have involved continuous cross-breeding between the two populations. The results are an initial point of reference for the classification of archaeological remains of prehistoric pig in the Iberian Peninsula, a key area for the study of the dynamics of neolithisation.

Keywords

early- and middle-Holocene Iberian Peninsula osteometry pig domestication pig husbandry

Introduction

The dynamics of animal domestication processes in the Iberian Peninsula are being studied profusely at the present time particularly because of the contribution this topic can potentially make towards understanding the neolithisation phenomenon in the western Mediterranean. Several millennia separate the first material manifestations of neolithisation in the Near East and in Iberia as the presence of the first domestic animals is documented millennia later in Iberia than in the former region. An eastern origin has traditionally been claimed for these first domesticates. However, recent publications stress the possibility of the domestication of autochthonous species in the case of bovids (Wright et al., 2014) and suids (Larson et al., 2005; Vai et al., 2015). For the latter species, palaeogenetic studies have identified several independent areas of domestication, which suggests the hypothesis of repeated domestication actions, spatially and temporally. Studies based on geometric morphometrics correlated with palaeomolecular analysis of a large collection of pig molars found at Neolithic sites in the Balkan Peninsula equally indicate that the domestication of this species may have included numerous modalities, with a continuous flow between wild and domestic populations (Evin et al., 2015). The possibility also of access, through exchange or hunting feral animals, to domestic animals by Mesolithic hunter-gatherers in southern Scandinavia and northern Germany, suggested by mutations detected in the MC1R gene associated with the colour of the coat (Krause-Kyora et al., 2013), is further evidence that animal domestication or the inclusion of domestic animals in subsistence was the result of diverse pig management strategies, some of which may have led to their domestication.

This historical issue of the first experiences in animal domestication has been studied through different perspectives (Saña, 1999, 2005; Vigne, 2015; Zeder, 2012). Whereas in zoological or environmental approaches, the emphasis is placed on the animal per se; in historical approaches, the weight of the analysis falls on the social formation responsible for the process, without whom the transition from wild to domestic condition would have been impossible. In the framework of the latter approach, several views can be differentiated (Saña, 1999, 2005). From the economic viewpoint, the conceptualisation of the animal as a resource has led to the domestication process being understood as a continuous series of stages each defined by the specific type of relationship existing between society and the animal resources. However, it is still difficult to determine in which stage the animal can be regarded as domestic. Although integral analytical approaches (biometry, stable isotopes, palaeogenetics and geometric morphometrics; Vigne et al., 2005) are now able to identify stages or situations that had been archaeologically invisible, by themselves their resolution is not sufficient to determine the initial animal domestication. This is only possible through a social approach embracing all the changing relationships that would allow continued control over reproduction and restricted access to animal resources.

The data currently available about suids allow the proposal of several trajectories through which the control of their reproduction and therefore their domestication would be feasible (Dwyer, 1996; Nakai, 2012; Rowley-Conwy, 1995, 2001; Sillitoe, 2007). Some of these models were designed bearing in mind the ethnographic studies that have documented a wide range of strategies in the management of the reproduction of pigs in the initial phases of their domestication (Baldwin, 1979; Nakai, 2012; Yen, 1991). Zeder (2012) also suggests joint commensalism as a scenario leading to the domestication of this species. In this case, the greater sedentarism of populations in the early-Holocene may have encouraged wild boar to approach human settlements. However, the key issue lies in the criteria followed in the selection involved in reproduction, widely dependent on the strategies of adoption and maintenance of animals that are applied. According to the degree of interdependence between the wild population and the one managed directly by human groups, the results obtained in the ethnographic studies cited above can be summarised in three main scenarios. First, human action is limited to capturing infant or juvenile specimens that were born in the wild. In the second, reproductive females are monitored continually, and in the third, both males and females depend entirely on humans. In some situations, therefore, the flow between wild and domestic populations would be common (Marshall et al., 2014). This is especially true taking into account that because of their feeding habits and behaviour, the breeding and maintenance of this species can be based on extensive practices in which the animals do not live in confined or enclosed spaces (Albarella and Trentacoste, 2011; Hadjikoumis, 2012; Redding and Rosenberg, 1998).

The possibility of hybridisation between populations is therefore continual (Ramírez et al., 2015). This adds certain complexity to the study of initial animal domestication, as its archaeological representation based on faunal remains may be highly variable and difficult to identify. Several studies have underscored the difficulty in separating wild and domestic forms in the case of pigs (Mayer et al., 1998; Payne and Bull, 1988). Additionally, such aspects as the different degrees of inter-relation and mixing between the two and the potential presence of feral specimens should be considered. One of the criteria most often used in this situation is based on biometry (Albarella et al., 2006b; Evin et al., 2014; Mayer et al., 1998; Payne and Bull, 1988; Rowley-Conwy et al., 2012), although recently numerous analytical methods such as palaeogenetics (Krause-Kyora et al., 2013; Larson and Burger, 2013), stable isotopes and geometric morphometrics (Balasse et al., 2016; Evin et al., 2015) have been proposed.

In the case of the Iberian Peninsula, no integrated study has examined the variability in pig populations in the early- and middle-Holocene. Only the studies of Albarella et al. (2005, 2009), Davis and Mataloto (2012) and Davis and Detry (2013) integrate data from Portugal in order to examine the dynamics in the changes in size of wild and domestic pigs over a long period of time. Hadjikoumis (2010) also carried out a full study of pig farming in the post-Neolithic period in his doctoral thesis. More precisely, Altuna and Mariezkurrena (2011) have published a summary for northern Iberia based on the biometric differentiation between Sus scrofa and Sus domesticus, from the Upper Palaeolithic to the Middle Ages. The results prove the existence of size differences between the two populations that can be identified in archaeological remains. In the Iberian Peninsula, the criteria most often used to discriminate between the wild and domestic species have been biometrics, slaughtering patterns, morphological traits and the archaeological context. Some authors stress the implicit limitations when the assemblages belong to the early Neolithic (Altuna, 1980; Altuna and Mariezkurrena, 2011; Castaños, 1984, 1991).

In order to reconstruct the history of suid populations (Sus scrofa/Sus domesticus) and their management in Iberia during prehistory, this paper presents an exhaustive analysis of the biometric data currently available for different time periods. The goal is to infer the forms of management of these species between 10,000 and 800 cal. BC. In first place, the variability of Sus scrofa from the Epipalaeolithic to the Bronze Age is assessed and later compared diachronically with the characteristics of the domestic populations. The explanatory models formulated in Iberia in relation to the pig domestication process envisage a complex and varied situation in the early-Holocene, in accordance with the large and contrasting environmental variability in the peninsula. The empirical record reveals the existence of a few sites in the north of Iberia specialising in hunting wild boar in the early Neolithic, whereas at other sites domestic pig breeding was well established and hunting was very limited (Saña, 2013). Published biometric studies for particular sites suggest discontinuity between wild and domestic populations, which might be linked to the widespread adoption of the domestic form at most human settlements. However, given the diversity of scenarios that have recently been proposed and identified in other geographic areas and the methodological difficulties in differentiating between Sus scrofa and the first domestic forms, it is necessary to study this phenomenon diachronically from a territorial perspective to be able to infer the diversity of situations in which the domestication and adoption of domestic pigs took place.

Materials and methods

This study is based on the exhaustive statistical analysis of the biometric data in the eastern part of the Iberian Peninsula, as most of the sites with published archaeozoological studies are located in that area. The sample consists of 53 archaeological sites in the north and east of the peninsula (Figure 1), covering a time from 10,000 to 800 cal. BC (Table 1). The inclusion of sites in each period has respected the criteria followed by different researchers, using the general chronocultural systematisation for the Iberian Peninsula. Only data for adult individuals at well-dated sites with no taphonomic problems have been used. The systematisation of all the measurements enables a continuous interpretation of the data temporally, without any significant gaps of periods with no data. For the measurements, the standardised criteria published by von den Driesch (1976) have been followed, including cases in which Payne and Bull’s (1988) proposal has been possible. The attributions of the remains to Sus scrofa or Sus domesticus made by the different researchers have been followed, while remains with no specific attribution have also been included in the analysis for comparison, noting that this category is only represented at some Neolithic and Chalcolithic sites and that the sample of measurements is small and circumscribed to a few sites.

Figure 1.

Map with the location of the archaeological sites included in this study.

Table 1.

Information about the sites, chronology and characteristics of the sample.

Code	Site	Location	Cultural attribution	Date (BP)	Date (cal. BC)	NISP SC	NISP SD	NISP sp	n SC	n SD	n sp	Ref.
1a	Abauntz	Navarra	Azilian	9530 ± 300	9899–8206	7	–	–	3	–	–	Utrilla (1980) and Sancho (1995)
2	Aizpea	Navarra	Late Epipaleolithic	7160 ± 70	6211–5966	179	–	–	1	–	–	Castaños (2001)
3	Cubio redondo	Cantabria	Mesolithic	6630 ± 50	5631–5481	18	–	–	3	–	–	Castaños (2001)
4	Fragua	Cantabria	Mesolithic	6860 + 60	5850–5640	19	–	–	3	–	–	González Morales (2000) and Marin-Arroyo (2004)
5a	Marizulo	Gipuzkoa	Late Mesolithic	6425 ± 85	5534–5223	127	–	–	11	–	–	Altuna (1972, 1980) and Alvarez-Fernandez and Altuna (2013)
6	Mazaculos II (level 3)	Asturias	Mesolithic	7030 ± 120	6101–5667	48	–	–	4	–	–	González Morales (1995) and Marin-Arroyo and Morales (2009)
7a	Mendandia (level IV–III)	Navarra	Mesolithic	7210 ± 80	6239–5973	60	–	–	2	–	–	Castaños (2006)
8a	Nerja	Málaga	Epipaleolithic/Mesolithic	7240 ± 80	6336–6256	42	–	–	1	–	–	Boessneck and Driesch (1980) and Jordá and Aura (2008)
9	Urtiaga	Gipuzkoa	Azilian	8700 ± 170	8259–7490	86	–	–	9	–	–	Altuna (1972)
10	Zatoya (level Ib)	Navarra	Geometric Epipaleolithic	8260 ± 550	8751–6066	167	–	–	10	–	–	Barandiarán (1982) and Mariezkurrena and Altuna (1989)
7b	Mendandia (level III)	Navarra	Neolithic	6460 ± 40	5486–5337	32	–	–	12	–	–	Castaños (2006)
11	Espluga de la Puyascada	Huesca	Neolithic	4560 ± 80	3521–3020	–	36	–	–	4	–	Castaños (1984)
12	Reina Amalia	Barcelona	Early Neolithic	5670 ± 40	4611–4443	10	939	3	–	116	–	Navarrete (in preparation)
13	Cova del Frare	Barcelona	Early Neolithic	5800 ± 130	4950–4363	–	265	–	–	2	–	Navarrete and Saña (in preparation)
14	La Draga	Girona	Early Neolithic	6010 ± 70	5070–4721	75	629	13	–	170	–	Saña (2000, 2011)
15	Herriko Barra	Guipuzkoa	Mesolithic	5960 + 95	5077–4593	28	–	–	4	–	–	Mariezkurrena and Altuna (1995)
16	La Renke	Álava	Neolithic	5180 ± 100	4629	5	60	2	7	13	–	Ortiz (1989) and Altuna and Mariezkurrena (2001)
5b	Marizulo	Gipuzkoa	Neolithic	5285 + 65	5215–4717	106	–	–	1	–	–	Altuna (1972, 1980)
17	Benàmer	Alicante	Early Neolithic	6250 ± 50	5321–5192	2	–	10	2	–	2	Tormo (2011)
18	Caserna St Pau	Barcelona	Early Neolithic	6290 ± 50	5372–5205	18	199	91	6	18	5	Colominas et al. (2008)
8b	Cueva de Nerja	Málaga	Early Neolithic	6330 ± 40	5380–5217	2	120	–	–	1	–	Boessneck and Driesch (1980)
19	Cova de l’Or	Alicante	Early Neolithic	6265 ± 75	5381–5021	8	177	–	3	18	–	Pérez Ripoll (1980)
20	Cova de la Sarsa	Valencia	Early Neolithic	6506 ± 32	5533–5461	18	239	7	11	10	9	Boessneck and Driesch (1980)
21	Cova de les Bruixes	Castellón	Early Neolithic	6460 ± 140	5658–5205	1	–	–	1	–	–	Sarrión (2005)
22	Cueva de Chaves	Huesca	Early Neolithic	6770 ± 70	5555–5310	154	1217	–	40	26	–	Castaños (2004)
23	Cueva del Nacimiento	Jaén	Neolithic	5490 ± 120	4586–4005	44	–	–	2	–	–	Asquerino and López (1981)
1b	Abauntz	Navarra	Neolithic	6910 ± 120	6018–5621	7	–	7	2	–	–	Utrilla (1982) and Sancho (1995)
1c	Abauntz	Navarra	Chalcolithic	4205 ± 35	2831–2468	–	–	65	–	–	5	Utrilla (1980) and Sancho (1995)
24	Castillejos	Badajoz	Chalcolithic	3990 ± 40	2620–2450	–	444	–	–	10	–	Ziegler (1990)
25	Zambujal	Lisboa	Chalcolithic	3995 ± 35	2775–2400	135	3381	–	104	96	–	Driesch and Boessneck (1976)
26	Arenal de la Costa	Valencia	Chalcolithic	3890 ± 80	2575–2140	–	93	–	–	13	–	Martinez and Bernabeu (1993)
8c	Nerja	Málaga	Chalcolithic	3840 ± 140	2677–1896	–	59	–	–	3	–	Boessneck and Driesch (1980)
27	Fuente Flores	Valencia	Late Neolithic	4090 ± 40	2776–2562	9	53	–	5	12	–	Cabanilles (1988) and Cabanilles and Martínez (1988)
28	Ereta del Pedregal	Valencia	Chalcolithic	3930 ± 250	3098–1742	3	151	–	1	–	–	Pérez Ripoll (1990)
29	Las Pozas	Zamora	Chalcolithic	4425 ± 30	3117–2924	2	104	–	2	–	–	Morales (1992)
30	Los Millares	Almeria	Chalcolithic	4380 ± 100	3363–2866	36	–	–	5	28	–	Peters and Driesch (1990)
31	Jovades	Alicante	Chalcolithic	4810 ± 60	3706–3500	2	654	2	–	49	–	Martinez (1993)
32	Valencina de la Concepción	Sevilla	Chalcolithic	4135 ± 45	2864–2627	–	–	–	40	24	–	Hain (1982) and Nocete-Calvo et al. (2008)
33	Sao Pedro	Redondo	Chalcolithic	3940 ± 45	2570–2296	–	–	256	–	–	94	Davis and Mataloto (2012)
34	Acinipo	Málaga	Bronze Age	2770 ± 90	1160–790	–	408	–	–	18	–	Riquelme (1990) and Carrilero (1992)
35	Castro de Berbeia	Álava	Bronze Age	760 ± 80	1327–1120	5	232	–	3	–	–	Altuna (1978, 1980)
36	Cuesta del Negro	Granada	Bronze Age	3180 ± 50	1561–1376	10	687	–	18	27	–	Driesch (1979)
37	Azuer	Ciudad Real	Bronze Age	3541 ± 30	1956–1766	6	187	–	–	14	–	Driesch and Boessneck (1980) and Nájera et al. (2010)
38	Cabezo Redondo	Alicante	Bronze Age	3550 ± 55	1890–1540	20	150	–	4	22	–	Driesch and Boessneck (1969) and Hernández Pérez (2009)
39	Cerro de la Encina	Granada	Bronze Age	3590 ± 40	2039–1874	30	1006	–	38	34	–	Friesch (1987)
40	Lloma de Betxí	Valencia	Bronze Age	3565 ± 65	2050–1741	2	12	21	2	–	–	Sarrión (1994)
41	Castellón Alto	Granada	Bronze Age	3630 ± 50	2141–1882	5	485	–	–	6	–	Milz (1986)
42	Fuente Álamo	Almeria	Bronze Age	3635 ± 50	2141–1885	–	449	–	6	47	–	Driesch et al. (1985)
43	Can Roqueta	Barcelona	Bronze Age	3590 ± 85	2151–1737	1	7	–	–	25	–	Piña and Saña (2004)
44	Arenaza	Bizkaia	Bronze Age	3805 ± 70	2446–2116	5	114	–	8	–	–	Altuna (1980) and Altuna and Mariezkurrena (2008)
45	Pic dels Corbs	Valencia	Bronze Age	3010 ± 70	1427–1012	24	459	–	–	15	–	Barrachine and Sanchis (2008)
46	Los Husos	Álava	Bronze Age	3920 ± 100	2680–2132	8	10	–	2	–	–	Altuna (1980)
47	Cueva del Moro	Huesca	Bronze Age	3530 ± 70	1580–1480	550	107	–	11	16	–	Castaños (1991)
48	Loma de la Balunca	Granada	Bronze Age	3490 ± 50	1939–1689	–	161	–	–	4	–	Milz (1986)
49	Terrera del Reloj	Granada	Bronze Age	3440 ± 50	1859–1772	3	425	–	–	18	–	Milz (1986) and Mederos (1995)
50	Cerro de la Tortuga	Málaga	Bronze Age	–	–	1	107	–	–	4	–	Driesch (1973)
51	Cerro del Real	Granada	Bronze Age	–	1000–850	4	109	–	–	7	–	Driesch (1972)
52	Los Palacios	Guadalajara	Bronze Age	–	1960–1622	–	944	–	–	2	–	Driesch and Boessneck (1980)
53	Tabayà	Alicante	Bronze Age	3557 ± 26	2010–1777	30	–	–	–	3	–	Rizo (2009) and Hernandez and López (2010)

SC: Sus scrofa; SD: Sus domesticus; Sus sp.; n: number of measurements.

The data have been compared with the log ratio technique (Meadow, 1999), using the data published by Albarella and Payne (2005) as the theoretical population. The comparison used the following logarithmic formula: (log x − log m) = log (x/m), where x is the measurement of the archaeological sample and m is the measurement of the standard population. Based on the recommendations from several studies, wherever possible, dental remains have been studied separately from the post-cranial skeleton (Albarella et al., 2005; Rowley-Conwy et al., 2012). Based on the log size index (LSI) values, in order to compare the data according to chronology and geographic area, the Kruskal–Wallis test has been used, with a statistical significance probability threshold of α = 0.05 (Hammer et al., 2001). The distribution of the measurements in box plot diagrams has enabled the assessment of continuity and discontinuity between wild and domestic populations bearing in mind that the interquartile range and median are represented in the box. Finally, multivariate statistics have been applied to assess the data integrally. The procedure has been cluster analysis, with which the degree of similarity between the data has been evaluated to determine whether or not the population can be divided into different size sub-groups. To apply this latter procedure, the databases have been formed by counting the LSI values according to chronology for each of the samples.

Results

The results of the Sus scrofa sample are given first, comparing the variability obtained diachronically. Then, the characteristics of the Sus domesticus populations are described, and finally, the data are compared and analysed together.

Variability in Sus scrofa in the Iberian Peninsula from 10,000 to 800 cal. BC

First, the variability in Sus scrofa populations has been compared according to chronology and based on the log ratio values obtained, using box plot charts (Figure 2). The results reveal differential dynamics in wild boar size during prehistory, in agreement with the values of the descriptive statistical parameters obtained for each sample (Table 2). Between 10,000 and 5700 cal. BC, Sus scrofa displays greater homogeneity and a smaller size than in the Neolithic (5700–3500 cal. BC). After that time, the tendency is towards a gradual increase in wild boar size until the Bronze Age (2500–800 cal. BC). This trend is clearly reflected in the mean values of each population, ranging from 0.04 in the Epipalaeolithic to 0.07 in the late Bronze Age. The variability in each time interval also differs, with a maximum in the Chalcolithic (SD = 0.06). Kruskal–Wallis p values (Table 3) attest statistically significant differences between Bronze Age populations and those in other chronological intervals. They also indicate continuity in size dynamics from the Epipalaeolithic to the Neolithic. Based on these results, a statistically significant turning point may be proposed, located temporally between 2500 and 800 cal. BC, when this species reaches its largest size. In order to assess the role that geography and climate may have played in this variability, the log ratio values for the time intervals corresponding to the Neolithic and Bronze Age have also been compared, differentiating between the osteometric data in northern Iberia and in the Mediterranean region. The data for the rest of periods have not been represented as the number of measurements is too small for some areas. The results (Figure 3) show that the Mediterranean specimens were relatively smaller than the ones in the north. However, in both the Mediterranean and northern regions, the size of the specimens increases between the early Neolithic and the Bronze Age. Kruskal–Wallis p values (Table 4) show that differences in the northern population between the Neolithic and Bronze Age are not significant.

Figure 2.

Box plot diagram with the Sus scrofa LSI values in chronological order.

Table 2.

Descriptive statistical parameters for the osteometric data used in Figure 2.

Cal. BC	10,000–7500	5700–3500	3500–2500	2500–800
N	47	91	157	92
Min	−0.05	−0.08	−0.12	−0.05
Max	0.13	0.15	0.15	0.15
Mean	0.04	0.05	0.04	0.07
Standard deviation	0.04	0.05	0.06	0.04

Table 3.

Kruskal–Wallis p values for the osteometric data from Figure 2.

Cal. BC	5700–3500	3500–2500	2500–800
10,000–7500	0.159	0.1279	0.00021
5700–3500		0.7752	0.01747
3500–2500			0.00328
2500–800

Figure 3.

Box plot diagram with the Sus scrofa LSI values, differentiating between the north-east zone (N) and the Mediterranean area (M) for the Neolithic and Bronze Age.

Table 4.

Kruskal–Wallis p values for the osteometric data from Figure 3.

Cal. BC		5700–3500		2500–800
Cal. BC		N	M	N	M
5700–3500	N		0.00266	0.0606	0.7923
5700–3500	M			1,11E-05	0.00068
2500–800	N				0.02475
2500–800	M

Finally, as differences in the dynamics of growth and plastic modification in elements of the post-cranial skeleton and teeth can affect the size and form of the animal differentially, as a consequence of different nature of the pressures, the data have been itemised according to that criterion (Figure 4). The results show greater relative variability in the post-cranial elements, where the Neolithic populations display the minimum and maximum values. It should equally be noted that between the Epipalaeolithic and early Neolithic, the size of teeth decreases relatively, while the other skeletal elements display the inverse trend.

Figure 4.

Box plot diagram with the Sus scrofa LSI values, differentiating between the values obtained for post-cranial skeletal elements (B) and teeth (T) in chronological order.

Variability in Sus domesticus in the Iberian Peninsula from 10,000 to 800 cal. BC

The number of measurements obtained for Sus domesticus in each time interval is larger than for Sus scrofa. The distribution of the log ratio values in box plot charts (Figure 5) indicates differential dynamics for the populations in each time interval. However, significant similarity is seen in the mean size of domestic pigs between 5700 and 2500 cal. BC. After this time, pig sizes tend to decrease, although with a greater degree of variability, similar to the situation in the early and middle Neolithic (Table 5). Kruskal–Wallis p values (Table 6) attest significant differences in the size of domestic pigs between the Neolithic-Chalcolithic and the Bronze Age. Specimens from the north and east of the peninsula have also been differentiated for Sus domesticus (Figure 6). In this case, differences in animal size in the two areas are not so great and are totally imperceptible during Bronze Age (Table 7). In all time intervals, greater variability is documented in the Mediterranean region. The distribution of the values according to skeletal element (Figure 7) displays great homogeneity in the measurements obtained for teeth and the post-cranial skeleton, although the post-cranial elements exhibit relatively higher means in all time periods (Table 8). However, Kruskal–Wallis p values (Table 9) reveal significant differences in the dynamics of bones and teeth in the various periods. The significant decrease in size documented after 2500 cal. BC affects both the post-cranial skeleton and teeth.

Figure 5.

Box plot diagram with the Sus domesticus LSI values in chronological order.

Table 5.

Descriptive statistical parameters for the osteometric data used in Figure 5.

Cal. BC	5700–3500	3500–2500	2500–800
N	378	235	262
Min	−0.22	−0.13	−0.24
Max	0.15	0.07	0.13
Mean	−0.02	−0.02	−0.04
Standard deviation	0.05	0.03	0.05

Table 6.

Kruskal–Wallis p values for the osteometric data from Figure 5.

Cal. BC	3500–2500	2500–800
5700–3500	0.4986	2.02E−05
3500–2500		4.93E−07
2500–800

Figure 6.

Box plot diagram with the Sus domesticus LSI values, differentiating between the north-east zone (N) and the Mediterranean area (M) for the Neolithic and Bronze Age.

Table 7.

Kruskal–Wallis p values for the osteometric data from Figure 6.

		5700–3500 cal. BC		2500–800 cal. BC
		N	M	N	M
5700–3500 cal. BC	N		2.89E−07	9.87E−05	1.44E−09
5700–3500 cal. BC	M			0.5948	0.969
2500–800 cal. BC	N				0.5787
2500–800 cal. BC	M

Figure 7.

Box plot diagram with the Sus domesticus LSI values, differentiating between the values obtained for post-cranial skeletal elements (B) and teeth (T) in chronological order.

Table 8.

Descriptive statistical parameters for the osteometric data used in Figure 6.

Cal. BC	5700–3500	3500–2500	2500–800	5700–3500	3500–2500	2500–800
Cal. BC	BN	BN	BN	TH	TH	TH
N	211	176	127	167	59	135
Min	−0.22	−0.13	−0.22	−0.14	−0.11	−0.24
Max	0.15	0.07	0.09	0.11	0.05	0.13
Mean	−0.03	−0.02	−0.04	−0.01	−0.01	−0.03
Standard deviation	0.059097	0.033733	0.050262	0.041463	0.036863	0.047359

Table 9.

Kruskal–Wallis p values for the osteometric data from Figure 7.

Cal. BC	5700–3500	3500–2500	2500–800	5700–3500	3500–2500	2500–800
Cal. BC	BN	BN	BN	TH	TH	TH
5700–3500	BN	0.3157	0.02802	3.46E−02	0.03785	0.07561
3500–2500	BN		0.000171	2.37E−01	0.05731	0.001396
2500–800	BN			7.96E−06	5.18E−05	0.656
5700–3500	TH				0.4481	5.20E−05
3500–2500	TH					0.000258
2500–800	TH

Integrated analysis of pig population in the Iberian Peninsula, 11,500–800 cal. BC

Following the analytical procedure applied individually for Sus scrofa and Sus domesticus, the log ratio values have been represented jointly according to time intervals in order to make comparisons (Figure 8a), also including the category Sus sp. for comparative purposes (Figure 8b). The chart shows a tendency towards a separation between the two populations, especially after 2500 cal. BC, when the distributions of values of wild and domestic populations barely overlap. The most homogeneous populations would be those between 3500 and 2500 cal. BC, for both Sus scrofa and Sus domesticus. In contrast, the greatest variability in wild animals is seen in Neolithic populations, and in the Bronze Age for domestic pigs. The specimens corresponding to the category Sus sp. (Figure 8b) occupy an intermediate position, with values that are relatively closer to the domestic population in both the Neolithic and Chalcolithic. Kruskal–Wallis p values display similarities between this population and the Sus domesticus population in the Neolithic (p = 0.1) and Chalcolithic (p = 0.16). The general pattern obtained in Figure 8a is also represented in the results obtained in the cluster analysis of Euclidean distances (Figure 9), differentiating the wild species and the domestic pig based on two groupings. In the case of Sus scrofa, as the Kruskal–Wallis p values indicated, the most significant turning point was in the Chalcolithic. For Sus domesticus, the dynamic follows the same trend, with animal sizes relatively more similar between 7500 and 2500 cal. BC than in the Bronze Age.

Figure 8.

(a) Box plot diagram comparing the Sus scrofa and Sus domesticus LSI values in chronological order. (b) Comparison of the variability of the category of Sus sp. in relation to Sus scrofa and Sus domesticus.

Figure 9.

Cluster diagram with the distances between the LSI values according to species and chronology (SUDO: Sus domesticus; SUSC: Sus scrofa).

Discussion

The size variability of pig populations in prehistory reflects the different selective pressures they were subjected to, either environmental or social. The documentation of different dynamics for Sus scrofa and Sus domesticus during the period studied here clearly demonstrates this. Whereas in the Holocene wild populations tended to increase in size, domestic populations decreased and the maximum difference between the two was reached after 2500 cal. BC.

The increase in size of Sus scrofa in the Holocene has been documented in other parts of Europe (Albarella et al., 2006a, 2006c; Rowley-Conwy, 1995), and particularly in Portugal during the Chalcolithic (Albarella et al., 2005; Davis and Mataloto, 2012). Several reasons have been put forward for this, such as the temperature and climate, and relaxation in selective pressure on this species related to hunting activity (Albarella et al., 2005, 2006b; Davis and Detry, 2013; Davis and Mataloto, 2012). According to these authors, the greater pressure exercised on the species in the Mesolithic would be a consequence of demographic growth, and later the stress caused by the intensive hunting of the species decreased because of the availability of domestic animals, from which most of the necessary proteins would be obtained. The inverse correlation between climate and size has been attested by a number of authors in the case of pig (Davis, 1981; Davis and Simões, 2016; Magnell, 2004; Mayer et al., 1998; Rosell et al., 2001; Rowley-Conwy et al., 2012). This is also evidenced in this study on a small scale by comparing the samples from northern Iberia with those from the Mediterranean area. The mean size in the latter area is slightly smaller, especially for the older wild boar populations (Epipalaeolithic/Mesolithic). The difference decreases from 2500 to 800 cal. BC, possibly as a result of the species adapting to the anthropic environment.

The greater relative variability in both Sus scrofa and Sus domesticus populations in 5700–3500 cal. BC coincides with the initial domestication or adoption of the species in the Iberian Peninsula. The greater difficulty in discerning between the remains of the two species is a factor that may have influenced this result. Aspects derived from the different forms of domestication or integration of the domestic species in subsistence strategies of the last hunter-gatherers and first Neolithic communities should also be considered. The exhaustive analysis of the data on the management of pigs in Iberia in the early Neolithic indicates that different forms of husbandry were practised (Saña, 2013). At the same time, as hunting Sus scrofa intensified at some Neolithic cave sites in the north, such as Zatoya (5743–4590 cal. BC) and Marizulo (5214–4718 cal. BC), in other areas intensification in pig farming has been documented. One of the clearest examples is the open air settlement of La Draga (5200–4720 cal. BC) in north-east Iberia, where a pattern of the selective slaughtering of males at the time of their meat optimum, in order to maximise meat production, has been recorded (Saña, 2011, 2015). This practice has also been proposed, based on demographic patterns, at the Neolithic site of Cueva de Chaves in Aragon (5740–5490 cal. BC; Castaños, 2004). While at La Draga biometry has proven the presence of two groups of different sizes, one of them coinciding with a domestic population (Saña, 2011), the size of the pigs at the early Neolithic site of Cueva de Chaves is relatively larger, similar to a wild population, and according to Castaños (2004), it may represent an example of mixed breeding.

Several factors may have contributed to this greater variability. During the initial phases of domestication and husbandry, crossing domestic animals with wild specimens may have been common, whether intentional or not. Ethnographic studies have described extensive strategies in pig farming, and such strategies favour cross-breeding (Albarella et al., 2006a; Marshall et al., 2014). Palaeogenomic studies on this species (Larson and Burger, 2013) stress that in the different stages of domestication, phenomena of admixture and introgression would be common. As genome data are available for more animal species, cross-breeding is seen to have been a common phenomenon (Orozco-Terwengel and Bruford, 2014). The greater degree of relative variability seen in Sus scrofa between 7500 and 3500 cal. BC compared with older (11,500–5700 cal. BC) and more recent chronologies (3500–800 cal. BC) may also be indicative of this situation, as the phenotype variability increased as a consequence of hybridisation (Šprem et al., 2011). An increasing number of studies have shown that after domestication, pigs can again acquire the characteristics of the wild population through the phenomenon of feralisation (Giuffra et al., 2000). Although it is now possible to follow and identify these situations with geometric morphometrics and palaeogenetics (Evin et al., 2015), in the present case, biometry is able to approach the matter only in terms of variability. In this respect, considering the variability and overlapping seen in the early Neolithic, the potential contribution of Iberian Sus scrofa populations to the formation of domestic herds cannot be ignored.

Other factors often cited in relation to the decrease in size of specimens during the initial phases of domestication include changes in mobility patterns due to constraints on movement (Lasota-Moskalewska et al., 1987) and a poorer diet and increase in stressful situations (Davis and Detry, 2013; Dobney and Ervynck, 2000). These situations would all arise with more frequent direct contact between pigs and human settlements. Archaeological data are unable to determine the number of animals in the first domestic herds. The practice of strategies based on semi-freedom would favour mixing or contact with wild animals, and cross-breeding between animals with a different status would be common (Bartosiewicz et al., 2006; Nakai, 2012), which would result in transitional phenotypes (Benecke, 1994). Several scholars agree that the systematic practice of breeding in confinement compared with a more extensive management would not have become established until the Middle Ages (Albarella et al., 2009; Ervynck et al., 2007; Thomas et al., 2013). Given the wide ecological adaptability of Sus scrofa (Scandura et al., 2008), if animals approached or entered settlements, they would have added farming sub-products or the waste of human consumption to their diet (Fraser et al., 2013). Results of carbon and nitrogen isotope studies reveal significant changes in the diet of pigs between the Neolithic and Iron Age (Hamilton et al., 2009), and a trend towards greater diversification has also been noted between the Neolithic and the Bronze Age (Madgwick et al., 2012). The seasonal amount and availability of food are key variables directly affecting the rates of growth and reproduction of animals (Férnandez-Llario and Mateos-Quesada, 1998; Halstead and Isaakidou, 2011). In this way, the gradual decrease in size of Sus domesticus from the Neolithic would be the result of increasingly constant selective pressure to which the species was subjected through a direct control over its feeding, raising and reproduction by human communities.

This decrease becomes more evident after 2500 cal. BC. As can be seen in Figure 8, the difference between the sizes of Sus scrofa and Sus domesticus in the Iberian Peninsula increases after 3500 cal. BC at the same time as the degree of variability in Sus domesticus populations decreases. In some Bronze Age settlements, such as Fuente Álamo and Cerro de la Encina, the difference between the wild and domestic forms is particularly clear (Driesch, 1987; Driesch et al., 1985). Once domesticated and subjected to conditions of artificial husbandry, the possibilities of genetic isolation between the wild and domestic populations are greater (Rowley-Conwy et al., 2012). In this context, the relatively more direct selection by Neolithic communities of animals for consumption and reproduction would have contributed in the medium or long term towards modifying the natural demographic patterns of the species. Control over reproduction patterns would undoubtedly have been a key variable, favouring significant changes in the growth rate and sexual maturity of the species. The trend for Sus domesticus seen in the box plot diagrams suggests that these selective pressures would have been increasingly intense. However, they probably occurred at different rates and in different ways depending on the means and needs of each prehistoric community. They are therefore not linear and were not the same in the whole of the Iberian Peninsula.

This differential dynamics in the management of domestic pigs, with unequal degrees of intensity and different directions of selective pressure, would probably have contributed to increasing variability in the species, as the results for the Bronze Age have shown. It should be noted that the relative homogeneity documented in Sus domesticus samples between 3500 and 2500 cal. BC may be conditioned by the small number of sites with remains that have been studied corresponding to this period. However, the trend towards a decrease in size is confirmed later, in the Bronze Age, with a mean of −0.04 compared with −0.02 in the preceding time interval. In this way, the control exercised on domestic populations led to a relaxation in the mechanisms of natural selection. This may explain the differential dynamic seen in sizes of wild boar and domestic pig in the north compared with the Mediterranean area, while the difference is practically imperceptible for domestic pigs in 2500–800 cal. BC. Differences in the mechanisms of selection are also observed in the individualised study, when possible, of dental remains and the post-cranial skeletal elements. Greater homogeneity is attested in the case of domestic populations. Studies of more recent samples, dated in the Roman, medieval and modern periods, show that after the Roman age, pig sizes vary significantly, with a large relative decrease in size in the Middle Ages and an increase in the modern age. This increase is attributed, in both the modern and Roman periods, to the application of zootechnical improvements (Grau-Sologestoa, 2015).

Conclusion

The study of animal domestication processes through analytical procedures based on biometry reveals the difficulty in explaining the diversity of situations and interactions that may have occurred between human communities and pig populations in the early- and mid-Holocene. It is clearly necessary to examine the domestication phenomenon through large conceptual categories that are not based exclusively on the wild/domestic dichotomy (Evin et al., 2015; Rowley-Conwy et al., 2012; Saña, 1999; Vigne, 2015; Zeder, 2012). Biometric analysis of the archaeological remains of Sus scrofa and Sus domesticus recovered at Iberian sites dated from 10,000 to 800 cal. BC shows that it was precisely during the early Neolithic (5700–3500 cal. BC) when the archaeological representation of pig management strategies displayed greatest variability. This should be associated with the economic and social changes derived from the adoption of livestock farming, which emphasised anthropic pressures in comparison with ecological ones. The different trajectories documented in the changes in size of Sus scrofa and Sus domesticus indicate that the adoption of pig farming was a relatively rapid process. The great capacity of adaptation of this species undoubtedly helped its breeding in artificial conditions, and it soon became a basic component in farming strategies. Specialisation in the hunting of Sus scrofa by the last hunter-gatherer societies shows that they were fully aware of its requirements in the early-Holocene and that it was an important part of their diet. Indeed, farming and hunting were not mutually exclusive but complementary activities in the Neolithic. Unlike other animals, such as goats, sheep and cattle, pigs were kept exclusively for raw materials and meat. The control of meat supplies was probably a direct cause for them being raised in artificial conditions to ensure their reproduction. From that time on, as seen in the changes in the size of the animals, domestic and wild populations followed different paths that did, however, occasionally converge. As it is a species with relatively fast gestation cycles and growth rates (Rosell et al., 2001), the differentiation from the wild population would also be more rapid than in the case of larger mammals. The differences evidenced in teeth size compared with post-cranial skeletal elements also point to the existence of flow between populations, either by direct dislocations or influenced by human action. Additionally, environmental and climate changes in the Mediterranean area at the end of the middle-Holocene (Zanchetta et al., 2016) may have conditioned new adaptations, particularly in the wild population.

Therefore, multiple and diverse variables converged during the initial domestication and adoption of pigs by the first farming communities. It has been shown that Sus scrofa and Sus domesticus responded to the various factors in different ways, which will doubtlessly facilitate the study of the dynamic and management of pigs in recent prehistory through the analysis of archaeological faunal remains.

Footnotes

Acknowledgements

The authors thank the reviewers and the Editor, whose comments greatly improved the original manuscript.

Funding

This work was developed in the frame of the project HAR2014-60081-R (Producción animal y cerámica en el neolítico peninsular. Estudio biogeoquímico integrado del consumo y las practicas culinarias) funded by Ministerio de Economía y Competitividad, Spain.

References

Albarella

Payne

(2005) Neolithic pigs from Durrington Walls, Wiltshire, England: A biometrical database. Journal of Archaeological Science 32: 589–599.

Albarella

Trentacoste

(2011) EthnoZooArchaeology: The Present and Past of Human–Animal Relationships. Oxford: Oxbow Books.

Albarella

Dobney

Rowley-Conwy

(2006a) The domestication of the pig (Sus scrofa): New challenges and approaches. In: Zeder

Bradley

Emshwiller

et al (eds) Documenting Domestication: New Genetic and Archaeological Paradigms. Berkeley, CA: University of California Press, pp. 209–227.

Albarella

Dobney

Rowley-Conwy

(2009) Size and shape of the Eurasian wild boar (Sus scrofa) with a view to the reconstruction of its Holocene history. Environmental Archaeology 14: 103–136.

Albarella

Davis

SJM

Detry

et al (2005) Pigs of the ‘Far West’: The biometry of Sus from archaeological sites in Portugal. Anthropozoologica 40: 27–54.

Albarella

Manconi

Rowley-Conwy

et al (2006b) Pigs of Corsica and Sardinia: A biometrical re-evaluation of their status and history. In: Tecchiati

Sala

(eds) Archaeozoological Studies in Honour of Alfredo Riedel. Bolzano: Province of Bolzano, pp. 285–302.

Albarella

Tagliacozzo

Dobney

et al (2006c) Pig hunting and husbandry in prehistoric Italy: A contribution to the domestication debate. Proceedings of the Prehistoric Society 72: 193–227.

Altuna

(1972) Fauna de Mamíferos de los yacimientos prehistóricos de Guipúzcoa. Con catálogo de los mamíferos cuaternarios del Cantábrico y del Pirineo Occidental. Munibe 24(1–4): 1–464.

Altuna

(1978) Restos óseos del Castro de Berbeia (Barrio, Álava). Estudios de Arqueología Alavesa 9: 225–244.

10.

Altuna

(1980) Historia de la domesticación animal en el País Vasco desde sus orígenes hasta la romanización. San Sebastián: Sociedad de Ciencias Aranzadi.

11.

Altuna

Mariezkurrena

(2001) La cabaña ganadera del yacimiento de La Renke (Álava, Pais Vasco). Munibe 53: 75–86.

12.

Altuna

Mariezkurrena

(2008) Restos de alimentación de origen animal de los pobladores de la cueva de Arenaza I (País Vasco) durante la Edad del Bronce. Veleia 24–25: 843–877.

13.

Altuna

Mariezkurrena

(2011) Diferenciación biométrica de Sus scrofa y Sus domesticus en yacimientos arqueológicos del norte de la Península Ibérica. Kobie 30: 5–22.

14.

Alvarez-Fernandez

Altuna

(2013) La cueva de Marizulo (Urnieta, Gipuzkoa), 50 años después: Revisión de los restos arqueozoológicos de los niveles mesolíticos. Kobie 32: 131–152.

15.

Asquerino

López

(1981) La cueva del Nacimiento (Pontones): Un yacimiento neolítico en la Sierra del Segura. Trabajos de Prehistoria 38: 109–152.

16.

Balasse

Evin

Tornero

et al (2016) Wild, domestic and feral? Investigating the status of suids in the Romanian Gumelniţa (5th mil. cal BC) with biogeochemistry and geometric morphometrics. Journal of Anthropological Archaeology 42: 27–36.

17.

Baldwin

(1979) Operant studies on the behaviour of pigs and sheep in relation to the physical environment. Journal of Animal Science 49: 1125–1134.

18.

Barandiarán

(1982) Datación por el C14 de la cueva de Zatoya. Trabajos de Arqueología Navarra 3: 43–57.

19.

Barrachina

Sanchis

(2008) Valoración diacrónica de un modelo económico de la edad del bronce: La fauna del poblado de Pic dels Corbs, Sagunt (Valencia). Quaderns de Prehistòria i Ar-queologia de Castelló 26: 43–94.

20.

Bartosiewicz

Boroneanţ

Bonsall

et al (2006) Size ranges of prehistoric cattle and pig at Schela Cladovei (Iron Gates region, Romania). Analele Banatului 14(1): 23–42.

21.

Benecke

(1994) Der Mensch und seine Haustiere. Die Geschichte einer jahrtausendealten Beziehung. PhD Thesis. Stuttgart: Theiss.

22.

Bernabeu

(1993) El III milenio a.C. en el País Valenciano. Los poblados de Jovades (Cocentaina, Alacant) y Arenal de la Costa (Ontinyent, València). Saguntum 26: 9–180.

23.

Boessneck

(1969) Restos óseos de animales del Cerro de la Virgen, Orce y del Cerro del Real, Galera, Granada. Noticiario arqueológico hispánico 10–12: 172–189.

24.

Boessneck

Driesch

(1980) Tierknochenfunde aus vier Südspanischen Höhlen. Tierknochenfunde von der Iberischen Halbinsel 4: 1–83.

25.

Cabanilles

Martínez

(1988) Fuente Flores (Requena, Valencia). Nuevos datos sobre el poblamiento y la economía del Neo-Eneolítico valenciano. Archivo de Prehistoria Levantina XVIII: 181–231.

26.

Carrilero

(1992) El proceso de trasformación de las sociedades indígenas de la periferia tartésica. La colonización fenicia en el sur de la Península Ibérica. 100 años de investigación. Granada: Instituto de Estudios Almerienses.

27.

Castaños

(1984) Estudio de los restos óseos de la Cueva de Espluga de la Puyascada (Huesca). Bolskan 4: 43–56.

28.

Castaños

(1991) Estudio de los restos faunísticos de La Cueva Del Moro (Olvena-Huesca). Bolskan 8: 79–107.

29.

Castaños

(2001) Estudio arqueozoológico de la fauna del Yacimiento de Cubío Redondo (Matienzo, Cantabria). Munibe 53: 71–74.

30.

Castaños

(2004) Estudio arqueozoológico de los macromamíferos del neolítico de la cueva de Chaves (Huesca). Saldvie 4: 125–171.

31.

Castaños

(2006) Estudio arqueozoológico de la fauna de Mendandia (Sáseta, Treviño). In: Alday

(ed.) El legado arqueológico de Mendandia: los modos de vida de los últimos cazadores-recolectores en la prehistoria de Treviño. Arqueología en Castilla y León Memorias 15. Castilla y León: Junta de Castilla y León, pp. 435–456.

32.

Colominas

Lladó

Saña

et al (2008) La gestió dels recursos animals durant les ocupacions de l’assentament de la caserna de Sant Pau. Quarhis 4: 55–61.

33.

Davis

(1981) The effects of temperature change and domestication on the body size of late Pleistocene to Holocene mammals of Israel. Paleobiology 7: 101–114.

34.

Davis

Detry

(2013) Crise no Mesolítico: Evidências zooarqueológicas. In: Arnaund

Martins

Neves

(eds) Arqueologia em Portugal-150 Anos. Lisboa: Associação dos Arqueólogos Portugueses, pp. 297–309.

35.

Davis

Mataloto

(2012) Animal remains from Chalcolithic Sao Pedro (Redondo, Alentejo): Evidence for a crisis in the Mesolithic. Revista Portuguesa de Arqueologia 15: 47–85.

36.

Davis

Simões

(2016) The velocity of Ovis in prehistoric times: The sheep bones from early Neolithic Lameiras, Sintra, Portugal. Monografias AAP 2: 51–66.

37.

Dobney

Ervynck

(2000) Interpreting developmental stress in archaeological pigs: The chronology of linear enamel hypoplasia. Journal of Archaeological Science 27: 597–607.

38.

Driesch

(1972) Osteoarchäologische Untersuchungen auf der Iberischen Halbinsel. Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 3: 128–129.

39.

Driesch

(1973) Nahrungsreste tierischer Herkunft aus einer tartessischen und einer spätbronzezeitlichen bis iberischen Siedlung in Südspanien. Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 4: 9–31.

40.

Driesch

(1976) A Guide to the Measurement of Animal Bones from Archaeological Sites (Peabody Museum Bulletin 1). Cambridge, MA: Peabody Museum of Archaeology and Ethnology.

41.

Driesch

(1979) Die tierischen Beigaben in den Gräben der Siedlung Cuesta del Negro bei Purullena, Granada. Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 6: 112–117.

42.

Driesch

Boessneck

(1969) Die fauna des ‘Cabezo Redondo’ bei Villena (prov. Alicante). Studien über frühe Tirkno-chenfunde der Iberischen Halbinsel 1: 43–90.

43.

Driesch

Boessneck

(1976) Die Fauna vom Castro do Zambujal. Studien uber fruhe Tierknochenfunde von der Iberischen Halbinsel 5: 4–129.

44.

Driesch

Boessneck

(1980) Die Motillas von Azuer und Los Palacios (Prov. Ciudad Real). Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 7: 84–121.

45.

Driesch

Boessneck

KokabIM et al (1985) Tierknochenfunde aus der Bronzezeitlichen Höhensiedlung Fuente Álamo, Provinz Almeria. Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 9: 1–75.

46.

Dwyer

(1996) Boars, barrows and breeders: The reproductive status of domestic pig populations in mainland New Guinea. Journal of Anthropological Research 52(4): 481–500.

47.

Ervynck

Lentacker

Müldner

et al (2007) An investigation into the transition from forest dwelling pigs to farm animals in medieval Flanders, Belgium. In: Albarella

Dobney

Ervynck

et al (eds) Pigs and Humans: 10,000 Years of Interaction. Oxford: Oxford University Press, pp. 171–193.

48.

Evin

Cucchi

Escarguel

et al (2014) Using traditional biometrical data to distinguish West Palearctic wild boar and domestic pigs in the archaeological record: New methods and standards. Journal Archaeological Science 43: 1–8.

49.

Evin

Dobney

Schafberg

et al (2015) Phenotype and animal domestication: A study of dental variation between domestic, wild, captive, hybrid and insular Sus scrofa. BMC Evolutionary Biology 15(1): 1.

50.

Férnandez-Llario

Mateos-Quesada

(1998) Body size and reproductive parameters in the wild boar Sus scrofa. Acta Theriologica 43: 439–444.

51.

Fraser

Bogaard Schäfe

Arbogast

et al (2013) Integrating botanical, faunal and human stable carbon and nitrogen isotope values to reconstruct land use and palaeodiet at LBK Vaihingen an der Enz, Baden-Württemberg. World Archaeology 45(3): 492–517.

52.

Friesch

(1987) Die Tierknochenfunde von Cerro de la Encina bei Monachil, Provinz Granada, (Grabungen 1977–1984). Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 11.

53.

Giuffra

Kijas

JMH

Amarger

et al (2000) The origin of the domestic pig: Independent domestication and subsequent introgression. Genetics 154(4): 1785–1791.

54.

González Morales

(1995) Memoria de los trabajos de limpieza y toma de muestras en los yacimientos de las Cuevas de Mazaculos y El Espinoso La Franca, Ribadedeva y La Llana (Andrín, Llanes) en 1993. Excavaciones Arqueológicas en Asturias 1991–94(3): 65–78.

55.

González Morales

(2000) La Prehistoria de las Marismas: Excavaciones en la Cueva de la Fragua (Santoña). Campañas de 1990, 1991, 1993, 1994 y 1996. In: Ontañón

(ed.) Actuaciones Arqueológicas en Cantabria 1984–1999. Santander: Consejería de Cultura y Deporte, pp. 93–96.

56.

Grau-Sologestoa

(2015) Livestock management in Spain from Roman to post-medieval times: A biometrical analysis of cattle, sheep/goat and pig. Journal of Archaeological Science 54: 123–134.

57.

Hadjikoumis

(2010) The origins and evolution of pig domestication in prehistoric Spain. PhD Thesis, Department of Archaeology, University of Sheffield, Sheffield.

58.

Hadjikoumis

(2012) Traditional pig herding practices in southwest Iberia: Questions of scale and zooarchaeological implications. Journal of Anthropological Archaeology 31(3): 353–364.

59.

Hain

(1982) Kupferzeitliche Tierknochenfunde aus Valencina de la Concepción/Sevilla (Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 8). Munich: UNI-Druck.

60.

Halstead

Isaakidou

(2011) A pig fed by hand is worth two in the bush: Ethnoarchaeology of pig husbandry in Greece and its archaeological implications. In: Albarella

Trentacoste

(eds) Ethnozooarchaeology: The Present and Past of Human-Animal Relationships. Oxford: Oxbow, pp. 160–174.

61.

Hamilton

Hedges

Robinson

(2009) Rooting for pigfruit: Pig feeding in Neolithic and Iron Age Britain compared. Antiquity 83: 998–1011.

62.

Hammer

Harper

Ryan

(2001) PAST: Paleontological statistics software package for education and data analysis. Palaeontologia Electronica 4(1): 9.

63.

Hernández Pérez

(2009) Tiempos de cambio. El final del Argar en Alicante. In: Hernández

López

Soler

(eds) En los confines del Argar. Una cultura de la Edad del Bronce en Alicante. Alicante: Museo Arqueológico de Alicante, pp. 292–305.

64.

Hernández Péraz

López

(2010) La muerte en el Argar alicantino. El Tabaià como paradigma. In: Pérez

Soler

(eds) Restos de Vida, restos de muerte. La muerte en la Prehistoria. Valencia: Diputación Provincial de Valencia, pp. 221–228.

65.

Jordá

Aura

(2008) 40 fechas para una cueva. Revisión crítica de 70 dataciones 14C del Pleistoceno superior y Holoceno de la Cueva de Nerja (Málaga, Andalucía, España). Espacio, Tiempo y Forma (I) 1: 239–256.

66.

Krause-Kyora

Makarewicz

Evin

et al (2013) Use of domesticated pigs by Mesolithic hunter-gatherers in northwestern Europe. Nature Communications 4: 1–7.

67.

Larson

Burger

(2013) A population genetics view of animal domestication. Trends in Genetics 29(4): 197–205.

68.

Larson

Dobney

Albarella

et al (2005) Worldwide phylogeography of wild boar reveals multiple centers of pig domestication. Science 307(5715): 1618–1621.

69.

Lasota-Moskalewska

Kobryń

Świeżyński

(1987) Changes in the size of the domestic and wild pig in the territory of Poland from the Neolitic to the Middle Ages. Acta Theriologica 32(5): 51–81.

70.

Madgwick

Mulville

Stevens

(2012) Diversity in foddering strategy and herd management in late Bronze Age Britain: An isotopic investigation of pigs and other fauna from two midden sites. Environmental Archaeology 17(2): 126–140.

71.

Magnell

(2004) The body size of wild boar during the Mesolithic in southern Scandinavia. Acta Theriologica 49(1): 113–130.

72.

Mariezkurrena

Altuna

(1989) Análisis arqueozoológico de los macromamíferos del yacimiento de Zatoya. Trabajos de arqueología Navarra 8: 237–266.

73.

Mariezkurrena

Altuna

(1995) Fauna de mamíferos del yacimiento costero de Herriko Barra (Zarautz, Pais Vasco). Munibe 47: 23–32.

74.

Marin-Arroyo

(2004) Análisis arqueozoológico, tafonómico y de distribución espacial de la fauna de mamíferos de la Cueva de la Fragua (Santoña, Cantabria). Munibe 56: 19–44.

75.

Marin-Arroyo

Morales

(2009) Comportamiento económico de los últimos cazadores-recolectores y primeras evidencias de domesticación en el occidente de Asturias. La Cueva de Mazaculos II. Trabajos de Prehistoria 66(1): 47–74.

76.

Marshall

Dobney

Denham

et al (2014) Evaluating the roles of directed breeding and gene flow in animal domestication. Proceedings of the National Academy of Sciences 111(17): 6153–6158.

77.

Martinez

(1993) La fauna de vertebrados. Saguntum 26: 123–152.

78.

Mayer

Novak

Brisbin

(1998) Evaluation of molar size as a basis for distinguishing wild boar from domestic swine: Employing the present to decipher the past. In: Nelson

(ed.) Ancestors for the Pigs: Pigs in Prehistory. Philadelphia, PA: MASCA (Research Papers in Science and Archaeology 15), pp. 39–54.

79.

Meadow

(1999) The use of size index scaling techniques for research on Archaeozoological collections from the Middle East. In: Becker

Manhart

Peters

et al (eds) Historia Animalaux Ex Ossibus. Festschrisft für Angela von den Driesch. Rahden/Westf: Verlag Marie Leidorf GmbH, pp. 285–306.

80.

Mederos

(1995) La cronología absoluta de la prehistoria reciente del sureste de la Península Ibérica. Pyrenae 26: 53–90.

81.

Milz

(1986) Die Tierknochenfunde aus drei argarzeitlichen Siedlungen in der Provinz Granada (Spanien). Studien über frühe Tierknochenfunde von der Iberischen Halbinsel, vol. 10. Munich: UNI-Druck.

82.

Morales

(1992) Estudio de la fauna del yacimiento calcolítico de ‘Las Pozas’ (Casaseca de Las Chanas, Zamora). Boletín del Seminario de Estudios de Arte y Arqueología 58: 65–96.

83.

Nájera

Molina

Jiménez-Brobeil

et al (2010) La población infantil de la Motilla del Azuer: Un estudio bioarqueológico. Complutum 21(2): 69–102.

84.

Nakai

(2012) Pig domestication processes: An analysis of varieties of household pig reproduction control in a hillside village in northern Thailand. Human Ecology 40(1): 145–152.

85.

Navarrete

(in preparation) Análisis faunístico del yacimiento neolítico de Reina Amalia (Barcelona).

86.

Navarrete

Saña

(in preparation) Territories and Livestock management in the northeast of the Iberian Peninsula during the early Neolithic: Complementarities and specialization between settlements.

87.

Nocete-Calvo

Queipo

Llano

Sáenz

et al (2008) The smelting quarter of Valencina de la Concepción (Seville, Spain): The specialized copper industry in a political centre of the Guadalquivir valley during the Third Millennium BC (2750–2500 BC). Journal of Archaeological Science 35: 717–732.

88.

Orozco-Terwengel

Bruford

(2014) Mixed signals from hybrid genomes. Molecular Ecology 23: 3941–3943.

89.

Ortiz

(1989) La Renke. Arkeoikuska 89: 16–19.

90.

Payne

Bull

(1988) Components of variation in measurements of pig bones and teeth, and the use of measurements to distinguish wild from domestic pig remains. ArchæoZoologia 2: 27–65.

91.

Pérez Ripoll

(1980) La fauna de vertebrados. In: Marti

(ed.) Cova de l’Or (Beniarrés-Alicante) (Serie de trabajos varios del SIP 65). Valencia: Diputación provincial de Valencia, pp. 193–255.

92.

Pérez Ripoll

(1990) La ganadería y la caza en la Ereta del Pedregal (Navarrés, Valencia). Archivo de prehistoria levantina XX: 223–254.

93.

Peters

Driesch

(1990) Archäozoologische untersuchung der tierreste aus der kupferzeitlichen siedlung von Los Millares (Prov. Almeria). Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 12: 51–109.

94.

Piña

Saña

(2004) Anàlisi arqueozoològica dels conjunts de restes de fauna recuperats al jaciment de Can Roqueta/Torre-romeu (Sabadell, Vallès Occidental). Barcelona: Prehistory Department, Barcelona Autonomous University, unpublished report.

95.

Ramírez

Burgos-Paz

Casas

et al (2015) Genome data from a sixteenth century pig illuminate modern breed relationships. Heredity 114(2): 175–184.

96.

Redding

Rosenberg

(1998) Ancestral pigs: A new (Guinea) model for pig domestication. In: Nelson

(ed.) Ancestors for the Pigs: Pigs in Prehistory. Philadelphia, PA: MASCA (Research Papers in Science and Archaeology 15), pp. 65–76.

97.

Riquelme

(1990) Aproximación al estudio faunístico del yacimiento arqueológico de Acinipo, Ronda (Málaga). Cuadernos de Prehistoria de la Universidad de Granada 14–15: 181–207.

98.

Rizo

(2009) Ganadería y caza durante la edad del bronce. Arqueozoología del Tabayá (Aspe, Alicante). Villena: Fundación Municipal José Maria Soler.

99.

Rosell

Fernández-Llario

Herrero

(2001) El jabalí (Sus scrofa Linnaeus, 1758). Galemys 13(2): 1–25.

100.

Rowley-Conwy

(1995) Wild or domestic? On the evidence for the earliest domestic cattle and pigs in South Scandinavia and Iberia. International Journal of Osteoarchaeology 5(2): 115–126.

101.

Rowley-Conwy

(2001) Determination of season of death in European wild boar (Sus scrofa ferus): A preliminary study. In: Millard

(ed.) Archaeological Sciences 1997. Proceedings of the Conference held at the University of Durham, 2–4 Sept 1997. British Archaeological Reports (International Series 939). Oxford: Archaeopress, pp. 133–139.

102.

Rowley-Conwy

Albarella

Dobney

(2012) Distinguishing wild boar from domestic pigs in prehistory: A review of approaches and recent results. Journal World Prehistory 25: 1–44.

103.

Saña

(1999) Arqueología de la domesticación animal: La gestión de los recursos animales en tell Halula (valle del Éufrates, Siria) del 8800 al 7000 BP. PhD Thesis, Universitat Autònoma de Barcelona.

104.

Saña

(2000) La gestió i explotació dels recursos animals. In: Bosch

Chinchilla

Tarrús

(eds) El poblat lacustre neolític de La Draga: Excavacions de 1990 a 1998. Girona: Museu d’Arqueologia de Catalunya-CASC, pp. 150–164.

105.

Saña

(2005) Animal domestication: Subject of study and subject of historical Knowledge. Revue de Paléobiologie 10: 149–154.

106.

Saña

(2011) La gestió dels recursos animals. In: Bosch

Chinchilla

Tarrús

(eds) El poblat lacustre del Neolític antic de la Draga. Excavacions 2000–2005. Girona: Monografies del CASC 9, pp. 177–212.

107.

Saña

(2013) Domestication of animals in the Iberian Peninsula. In: Colledge

Conolly

Dobney

et al (eds) The Origins and Spread of Domestic Animals in Southwest Asia and Europe. Walnut Creek, CA: Left Coast Press, Inc, pp. 195–220.

108.

Sancho

MFB

(1995) Estudio arqueozoológico de los niveles postpaleolíticos de la cueva de Abauntz (Arraiz, Navarra). Trabajos de arqueología Navarra 12: 23–42.

109.

Sarrión

(1994) Clasificación preliminar de la fauna. In: De Pedro

(ed.) La Lloma de Betxí (Paterna, Valencia) Un poblado de la Edad del Bronce. Valencia: Serie de Trabajos Varios del SIP 94, pp. 247–260.

110.

Sarrión

(2005) La fauna de la Cova de les Bruixes. In: Mesado

(ed.) La Cova de les Bruixes (Rossell. Castellón). Valencia: Serie de Trabajos Varios del SIP 105, pp. 77–109.

111.

Scandura

Iacolina

Crestanello

et al (2008) Ancient vs. recent processes as factors shaping the genetic variation of the European wild boar: Are the effects of the last glaciation still detectable? Molecular Ecology 17(7): 1745–1762.

112.

Sillitoe

(2007) Pigs in the New Guinea Highlands: An ethnographic example. In: Albarella

Dobney

Ervynck

et al (eds) Pigs and Humans: 10,000 Years of Interaction. Oxford: Oxford University Press, pp. 330–356.

113.

Šprem

Piria

Novosel

et al (2011) Morphological variability of the Croatian wild boar population. Šumarski list 135(11–12): 575–582.

114.

Thomas

Holmes

Morris

(2013) ‘So bigge as bigge may be’: Tracking size and shape change in domestic livestock in London (AD 1220–1900). Journal of Archaeological Science 40: 3309–3325.

115.

Tormo

(2011) Arqueozoologia. In: Torregrosa

Maestre

López

(eds) Benàmer (Muro d’Alcoi, Alicante). Mesolíticos y neolíticos en las tierras meridionales valencianas. Valencia: Serie de trabajos varios del SIP 112, pp. 113–117.

116.

Utrilla

(1980) Fechas de Carbono 14 para la Prehistoria del Valle del Ebro. Caesaraugusta 51–52: 5–9.

117.

Utrilla

(1982) El yacimiento de la cueva de Abauntz (Arraiz, Navarra). Trabajos de Arqueología Navarra 2: 203–345.

118.

Vai

Vilaça

Romandini

et al (2015) The Biarzo case in northern Italy: Is the temporal dynamic of swine mitochondrial DNA lineages in Europe related to domestication? Scientific Reports 5: 16514.

119.

Vigne

(2015) Early domestication and farming: What should we know or do for a better understanding? Anthropozoologica 50(2): 123–150.

120.

Vigne

Peters

Helmer

(2005) New archaeozoological approaches for the first steps of animal domestication: General presentation; reflections and proposals. In: Vigne

Peters

Helmer

(eds) New Methods and the First Steps of Mammal Domestication. Proceedings of the 9th International Council of Archeozoology (Durham, 23rd-28th August 2002). Oxford: Oxbow Books, pp. 1–16.

121.

Wright

Viner-Daniels

Pearson

et al (2014) Age and season of pig slaughter at Late Neolithic Durrington Walls (Wiltshire, UK) as detected through a new system for recording tooth wear. Journal of Archaeological Science 52: 497–514.

122.

Yen

(1991) Domestication: The lessons from New Guinea. In: Pawley

(ed.) Man and a Half: Essays in Pacific Anthropology and Ethnobiology in Honour of Ralph Bulmer. Auckland: The Polynesian Society, pp. 558–569.

123.

Zanchetta

Regattieri

Drysdale

et al (2016) The so-called ‘4.2 event’ in the central Mediterranean and its climatic teleconnections. Alpine and Mediterranean Quaternary 29(1): 5–17.

124.

Zeder

(2012) The domestication of animals. Journal of Anthropological Research 68(2): 161–190.

125.

Ziegler

(1990) Tierreste aus der prähistorischen siedlung von los Castillejos bei Montefrío (Prov. Granada). Studien über frühe Tierknochenfunde von der Iberischen Halbinsel 12: 1–50.