bronze age

3.6  Transportation and Movement

The consequences of human mobility in the Bronze Age archaeological record of Scotland are widespread. They can be traced by mapping the distributions of imported phenomena including: exotic raw materials such as jet (Sheridan and Davis 2002) from their source at Whitby, East Yorkshire; distinctive object types such as bronze swords (e.g. Colquhoun and Burgess 1988) or Food Vessels (e.g. Sheridan 2004; Brindley 2007) and technologies such as tin-bronze alloying (Needham 2004) and complex  bronze sheet metalworking (Gerloff 2010); and specific funerary practices such as Beaker graves (e.g. van der Linden 2006; Sheridan 2007). The increase in strontium isotope analysis with projects such as Beakers and Bodies and the Beaker People Project is beginning to allow the identification of individuals who moved into and subsequently died in a region different from that of their birth and early development. Identifying where they came from is still a matter of scientific debate (Pollard 2011). The evidence for Bronze Age settlement, funerary and agricultural activity throughout the vast majority of mainland Scotland as well as on the largest of the 790 islands (although only 62 exceed 3 square miles) including the Shetlands, Orkneys and Outer Hebrides implies that widespread land and maritime movement by people and animals had to have been occurring. Recent surveys of the maritime connections across the Irish Sea (Waddell 1992) and the North Sea (Van der Noort 2011) demonstrate substantial movement on Scotland’s exceptionally long coastline of 9,911 km. The marked similarities in many aspects of the Bronze Age archaeology of adjacent regions would have required regular movement whether over water as with northeast Ireland and southwest Scotland (Waddell 1992) or over land or water such as southeast Scotland and northeast England.

The problem in interpreting Bronze Age mobility is that there is so little surviving evidence for how it occurred. This strongly influences questions regarding the difficulty, scale and meaning. For instance, key questions that can only tentatively be addressed include:

  1. Was mobility a rare, specialist and ritual endeavour or a common, widely practiced and everyday activity?
  2. Were wheeled vehicles used only in ritual contexts or did Bronze Age farmers use wagons on a regular basis?
  3. When were horses first ridden and what role did they play in warfare?
  4. Was movement dominated by maritime and riverine activity as is frequently argued or were there major land routes?
  5. How mobile where Bronze Age communities? Were most people staying put whilst a minority travelled widely?

It is assumed that maritime and riverine movement would have been fundamental in Scotland yet there currently are no surviving sewn plank boats as in England and Wales (Van der Noort 2006) and, less surprisingly, no surviving hide boats (McGrail 2004, 63-4). The recent discovery of the c. 10m long oak Carpow log boat from the river Tay dated to 1130-970 BC has prompted its comprehensive analysis and publication (Strachan 2010), in contrast to many of the 150 logboats from Scotland whose dating clusters in the mid 1st millennium BC- end 1st millennium AD (see Mowat 1996). There is an earlier logboat fragment from Scotland – an oak fragment from Catherinefield, Dumfries and Galloway which dates to c. 2000 BC (see Mowat 1996, 18-20) but these two sites presumably represent a fraction of the Bronze Age logboats which were made and used. In addition to the logboats, there are also several known potentially prehistoric paddles and oars although none in Scotland appear to have been directly dated (see Strachan 2010, Chapter 8). The potential association of paddles with crannogs at Loch Kinord and Oakbank Crannog, Loch Tay represents the closest discovery confirmed dating – albeit to the very end of the Bronze Age at best (Mowat 1996, 97-101). There have only been a few attempts at assessing the performance of logboats. With a maximum of one paddler and 133kg of cargo or four light adults, a top speed of 2.5 knots could be achieved in the Carpow logboat (Strachan 2010, 120). It does not seem likely that these vessels could have regularly crossed the Irish or North seas, let alone made the notoriously difficult crossing to St Kilda which apparently first occurred during the Bronze Age (Fleming and Edmonds 1999) although proper experimental voyages would be required.

The evidence for land transport is equally fragmentary. The surviving tripartite wooden wheel made from ash found in a bog at Blair Drummond, Perthshire has been dated to 1255-815 BC (Piggott 1957; Sheridan 1996) and represents the only surviving wooden evidence for wagons or chariots. There are no surviving Bronze Age trackways in Scotland which would have accommodated wheeled vehicles. The dating of the domestication of the horse for riding rather than straightforward consumption is still under debate. The discovery of bronze horse- and chariot- gear in Late Bronze Age hoards such as at Glentanar, Aberdeenshire (Pearce 1971) and Horsehope, Peebleshire (Piggott 1955) together with the far more extensive evidence in continental Europe during the late 2nd-early 1st millennium BC indicates that chariots or wagons were being drawn by horses (see Pare 1992, 18-42) and presumably horses were being ridden in some capacity.

Carpow log boat under examination ©Trevor Cowie

There gap between the transport technology and the evidence for mobility of people, animals and goods is substantial. Rather than wheeled vehicles, land transport could be dominated by human carriers who would probably have been able to manage c. 20km a day with 20-35 kg or possibly by ox-drawn wagons which might cover 24-28 km an hour with heavier loads but would obviously require easier terrain (Piggott 1983, 89f; Uckelmann forthcoming).  When compared to continental Europe, it is striking how few objects relating to horses, wagons or chariots are found in Scotland, or indeed, the British Isles (cf. Balkwill 1973; Hüttell 1981; Piggott 1983; Uckelmann forthcoming).

3.5 Demography of the Bronze Age population in Scotland

Demography is the statistical study of human population which seeks to explain variations in population size, structure and dynamics by considering the population of a given area or chronological period as a single object for quantitative analysis (Chamberlain 2006). Changes in the number of individuals in a population through time will depend on a balance between birth and death, as well as movements of people into and out of the population.

Detailed demographic analysis of the Bronze Age population in Scotland has yet to be attempted although several aspects have been addressed, mainly as part of individual excavation reports. The lack of dedicated demographic research into this period is due to a number of complex challenges. Not least amongst these is the fact that there is still little idea of population numbers or structure. This is because much of the evidence derives from excavated assemblages of human remains which show remarkable bias in terms of age and sex as a result of selective burial practises, as well as incomplete preservation (Bradley 2007; Chamberlain 2000, 206).

Population

Attempts to estimate the population size of Scotland in the Bronze Age have been fraught with difficulties due to the long chronological period of time that this era encompasses. A population of 2,500 for Scotland has been suggested, contrasting sharply with overall British population estimates which range from between 20,000 to 100,000 (McEvedy and Jones 1978; Brothwell 1972).

These now outdated estimates were based on known burial populations which are likely to be severely biased due to selective burial practices (Bradley 2007). They also fail to take into consideration that it is unlikely that population numbers would have remained static over such a long period of time, particularly due to increasing evidence of climate change, shifting patterns of land-use and movements of people within northern Britain. All of these factors would have had implications to the Bronze Age population, namely the economy and diet, spread of disease and its effect on mortality rates. 

Population structure: age categories and distributions 

It is common practice to split age distributions into discrete biological age intervals, measured in units of months, years or multiple of years since birth. The simplest subdivision is to separate the lifespan into three groups based on chronological years and physiological development: sub-adult or child, adult and mature adult (Chamberlain 2006). The boundaries between these basic age groups can vary between the sexes but are thought to be founded on biological indicators, such as the development of sexual maturity in females.

There is little agreement on the definitions used to describe the age of children within archaeological populations (McLaren, forthcoming; Sofaer Derevenski 2000), however, demographic conventions define children as individuals less than 15 years of age (Chamberlain 2000, 207). Within a stable population, demographic models suggest that the segment of the total population constituted by children could vary from about 36% in a low life expectancy population to about 19% in the highest life expectancy populations (Chamberlain 2000, 207). This has profound implications to the wider population, as a higher infant mortality rate will result in fewer individuals reaching adulthood.

Survivorship

Survivorship is a useful demographic concept that expresses the probability that an individual will survive to a specified age. This is a contested subject; some argue that the small number of individuals over 45 years of age identified amongst the population is an indication that people died young. Others suggest, that this paucity of older and elderly individuals is, in fact, a product of bias in skeletal-age estimation which has failed to recognise old-adult individuals (Chamberlain 2006, 34). This is clearly an area which needs more work to clarify.

Health and disease

As the accuracy of osteological analysis of Bronze Age skeletal remains advance, the recognition of markers of disease, injury and dietary problems increases. Such palaeopathological studies provide important information for Bronze Age lifestyles and health and are vital to gaining an understanding of the demography of early prehistoric populations. In very few cases can the cause of death be determined, but useful information can be observed regarding joint disease due to physical stress, chronic infections, trauma and deficiency in diets (Shepherd and Bruce 1986, 17).

Degenerative joint disease

Osteological analysis of skeletal remains has demonstrated an increase in the frequency of joint disease during the Bronze Age, indicating increased stress on the joints due to strenuous physical activities, believed to be related to intensification of farming and exploitation of the land (Roberts and Cox 2003, 77). This includes evidence of spinal joint degeneration such as that on a 35-40 year old adult male at Cnip, Lewis (Bruce and Kerr 1995, 283) and Blackhills, Tyrie (Shepherd and Bruce 1986, 36), osteoarthritis of the wrist of an adult male at Grainfoot, Longniddry (Lorimer 1991, 114), degeneration of the hip joint such as that of a young adult male from Keabog, Pitdrichie (Shepherd and Bruce 1987, 37). Spinal lesions known as Schmorl nodes, a further indicator of degenerative spinal disease either due to age or as the result of heavy manual labour is known in a small number of individuals such as two adults from Grainfoot, Longniddry (Lorimer 1991, 113-4), Boyndlie, Aberdeenshire, Culduthel, Invernesshire and Kilspindie, East Lothian (Shepherd and Bruce 1986, 36-7).

Infection

Infection is likely to have been a major cause of death at all ages, but rarely leaves traces on the bones of the skeleton (Shepherd and Bruce 1986, 19).

Dental disease

Severe dental wear and disease is a characteristic feature of the Bronze Age population, reflective of the stresses inherent in a coarse diet (Roberts and Cox 2003, 80). Dental caries and abscesses have been observed on numerous individuals including a 35-40 year old adult male at Grainfoot, Longniddry (Lorimer 1991, 114) and adults from Boatbridge Quarry, Thankerton (Clarke et al. 1984), Mains of Leslie, Borrowstone and Persley Quarry, Aberdeenshire (Shepherd and Bruce 1986, 36), to name a few.

Trauma

Evidence of physical trauma is limited in the Scottish burial population during this period, but a few examples are known. Severe injuries could either as the result of repeated physical exertion, accidental injury or deliberate violence but is impossible, in most cases, to determine the cause (Roberts and Cox 2003, 80). Possible skull fractures have been noted in adult males from Hillhead and Ord, Aberdeenshire (Shepherd and Bruce 1986, 36) and a severe and extensive facial injury was noted on the skull of an adult male from Cnip, Lewis (Bruce and Kerr 1995). A healed skull fracture and a possible fracture of the thoracic spine has been observed on an adult male from Keabog (Shepherd and Bruce 1985).

Dietary deficiency

Indications of childhood illness and possible dietary deficiency can be observed in some instances from the skeletal remains in the form of enamel hypoplasia (banding on tooth enamel), cribra orbitallia (pitting on the roof of the orbits), harris lines (banding on long bones). These can only be formed during childhood, whilst the skeleton is still growing and typically indicate a period when growth has been severely impaired. Although not common, examples have been noted from a child at Auchlin, Aberdour (Reid 1924; Shepherd and Bruce 1986, 36). A peak in occurences in children around 2-3 years of age has been suggested as the result of weaning (Fuller et al. 2003). Possible instances of scurvy and rickets have been noted in south-west England (Mays 2007; Keith 1920).

Mortality

Mortality, or death rate, is defined as the proportion of the population that dies within a specific chronological interval. Although no accurate mortality figures are available for Bronze Age Scotland, high infant mortality is expected (Goodman and Armelagos 1989). It has been suggested that up to 40% of children born in prehistory, died before reaching 5 years-of-age (Goodman and Armelagos 1989, 225). Mortality rates are expected to peak at this early stage of childhood, then decease to minimal levels in late adolescence and early adult, and then rise steadily into old age (Chamberlain 2006, 25).

One notable exception to this is high death-rates in young adult females. Margaret Bruce’s study of Beaker associated burials from North-East Scotland identified a greater proportion of young-adult females amongst the deceased. Greater quantities of adult males appear to have survived into middle-age or later which is in contrast to adult females, a greater proportion of which appear to have died in early adulthood, between 15-25 years of age (Shepherd and Bruce 1986, 18). It is likely that this is directly related to childbearing and childbirth.

Mortality rates are not only tied to age and biological sex but would also vary according to socioeconomic status and other population parameters. This is more challenging to interpret in the case of Bronze Age Scotland due to the possibility of selective burial practices.

Migration and movement

There is increasing evidence for large-scale movement of peoples in the Bronze Age. In Scotland, indications of movement of individuals to and from Ireland are suggested by similarities in material culture. This movement of peoples into and out of Scotland could have had a profound affect on the population depending on the extent of such migrations, not only creating the possibility of increased pressure on settlements and resources but also effecting the distribution of disease.

Particularly during the Earlier Bronze Age there is evidence of the movement of peoples within and outwith Britain, demonstrated by Jane Evans and Janet Mongomery’s strontium isotope analysis programme conducted through the Beaker People Project. Strontium isotope analysis looks specifically at tooth enamel which is formed during early childhood. This enamel retains the isotopic signature of the underlying geology, absorbed by the body through water consumption, which relates to the early years of the individuals life (Fuller et al. 2003). Unfortunately, this process has its limitations as it is not possible to detect individuals that move between regions that have the same underlying geology (Chamberlain 2006, 9).