Ingrid Mainland

Revealing the History of Sheep Domestication Using Retrovirus Integrations

Sheep retroviruses can be used to map the selective preferences of early farmers and trace livestock movements across Europe. Not Just Dinner on Legs Several thousand years ago, human beings realized the virtues of domesticating wild animals as easy meat. Soon other possibilities became apparent, and as revealed in a series of papers in this issue, early pastoralists became selective about breeding for wool, leather, milk, and muscle power. In two papers, Gibbs et al. report on the bovine genome sequence (p. 522; see the cover, the Perspective by Lewin, and the Policy Forum by Roberts) and trace the diversity and genetic history of cattle (p. 528), while Chessa et al. (p. 532) survey the occurrence of endogenous retroviruses in sheep and map their distribution to historical waves of human selection and dispersal across Europe. Finally, Ludwig et al. (p. 485) note the origins of variation in the coat-color of horses and suggest that it is most likely to have been selected for by humans in need of good-looking transport. The domestication of livestock represented a crucial step in human history. By using endogenous retroviruses as genetic markers, we found that sheep differentiated on the basis of their “retrotype” and morphological traits dispersed across Eurasia and Africa via separate migratory episodes. Relicts of the first migrations include the Mouflon, as well as breeds previously recognized as “primitive” on the basis of their morphology, such as the Orkney, Soay, and the Nordic short-tailed sheep now confined to the periphery of northwest Europe. A later migratory episode, involving sheep with improved production traits, shaped the great majority of present-day breeds. The ability to differentiate genetically primitive sheep from more modern breeds provides valuable insights into the history of sheep domestication.

Dental microwear in grazing and browsing Gotland sheep (Ovis aries) and its implications for dietary reconstruction

Abstract Microwear patterns and formation processes are examined in modern browsing and grazing Gotland sheep from Denmark. Clear differences in microwear patterning are identified between Gotland sheep, which included a high proportion of leaves, bark and twigs of deciduous trees and shrubs in their diet, and those which primarily had access to graze species, with the browsing group exhibiting enamel surfaces dominated by pitted microwear features, the grazers a predominance of striations. Analysis of abrasives in dung suggests that these trends can be attributed to higher levels of soil ingestion in the grazing population and are a consequence both of grassland management practices and height of feeding within the vegetation canopy. These findings question previous interpretations of microwear patterning in browsing and grazing ungulates, which have equated striated enamel features with the ingestion of high levels of opal phytoliths, and thus have significant implications for palaeodietary reconstruction in such species, both within archaeological and palaeontological contexts. To address further the implications of these results, comparison is made between the Gotland sheep and modern grazing and fodder-fed sheep and goats from elsewhere in Europe. It is concluded that dental microwear analysis has the potential to address questions relating to grassland management practices and the use of certain fodders, such as leafy-hay, but that it may ultimately prove more difficult to distinguish ‘fresh’ browsing sheep from some grazing populations, specifically those in which levels of soil ingestion are reduced.

Stable isotope evidence for seasonal consumption of marine seaweed by modern and archaeological sheep in the Orkney archipelago (Scotland).

Abstract The use of seaweed as fodder for domestic animals during winter has been suggested for the North Atlantic isles in prehistory with reference to a historically attested practice. We tested the use of stable isotope analysis in tooth enamel bioapatite to detect seasonal consumption of seaweed on modern sheep from the Orkney archipelago, with no contribution, seasonal contribution or exclusive contribution of seaweed to diet. There was no overlap between the δ13C of local terrestrial vegetation and marine plants available on the shore. Sheep relying on seaweed had enamel δ13C values as high as −3·1‰, differing from grazing sheep with enamel δ13C values comprised between −17·7‰ and −15·1‰. Seaweed consumption was also reflected in lower amplitudes of intra-tooth variation in enamel δ18O values (0·3‰ to 1·8‰ in seaweed-eating sheep; 3·6‰ to 4·1‰ in grazing sheep), likely due to ingestion of oceanic water. The protocol was applied to archaeological assemblages from the same archipelago. A winter consumption of seaweed was detected in one sheep from the Neolithic site of Point of Cott and one sheep from the Iron Age assemblage of Mine Howe. No contribution of seaweed to the sheep diet was shown at the Late Norse site of Earls Bu.

A dental microwear study of seaweed-eating and grazing sheep from Orkney

The potential of dental microwear for recognizing the use of seaweed as fodder in the past is explored through the analysis of microwear patterning in modern seaweed-eating and grazing sheep from Orkney. Seaweed-eating and grazing sheep are clearly distinguished on the basis of microscopic dental wear patterns. This reflects an emphasis on anterior-posterior jaw movements and large pitted features in the seaweed-eaters and can be attributed to the differing forces and/or masticatory movements required in the comminution of grasses and seaweed. Differences between seaweed-eating and grazing individuals are maintained when the grazing group is expanded to include grazing sheep from Greenland and the Scottish borders. It is concluded that the microwear of seaweed-eating sheep is highly distinctive and that dental microwear analysis potentially has a widespread application for identifying seaweed grazing within Scotland and the North Atlantic islands. Copyright

The Economics of Sheep and Goat Husbandry in Norse Greenland

Insight into the relative importance of sheep and goat herding and of the economic significance of each species (i.e., milk vs. meat vs. wool) in Medieval Greenland is obtained through the application of Halstead et al.’s (2002) criteria for the identification of adult ovicaprine mandibles to faunal assemblages from three Norse farmsteads: Sandnes, V52a, and Ø71S. The economic strategies identified are broadly comparable between the two species and the Eastern and Western Settlement sites examined, and are suggestive of the subsistence production of meat and milk. Comparison with farmsteads elsewhere in Greenland indicates that socio-economic status and/or farmstead size interacted with geographical location in determining the economic strategies employed by the Norse farmers. A broader use of resources and a more varied diet are evident at larger farmsteads in Greenland and this paper suggests that such sites would have been better able than their smaller counterparts to withstand environmental deterioration during the early Middle Ages. These analyses have also confirmed that goats were relatively more common in Norse sites in Greenland than in Norse sites in Iceland, Orkney, or Shetland.

Dental microwear study of pigs from the classical site of Sagalassos (SW Turkey) as an aid for the reconstruction of husbandry practices in ancient times

Abstract Microwear analysis of pig teeth from the classical site of Sagalassos (SW Turkey) is undertaken to obtain insight into pig management strategies in this region from the 1st to 7th centuries AD. Earlier research on modern pigs revealed significant differences in microwear patterns between stall-fed and free-ranging, rooting individuals. A comparison of the microwear data of the Sagalassos pig with those from archaeological and modern pigs with a known or presumed type of management shows that the microwear of the Sagalassos pigs is very different. It is suggested that the Sagalassos pigs had a very soft, non-abrasive diet, that in the first instance cannot be attributed to either management type. Therefore, the nature of the substrate on which the animals were foraging and its impact on microwear are considered and the microwear data are compared with the results of previous archaeozoological research carried out at the site. Further, diachronic changes in microwear patterns are investigated.