Internet Archaeol. Laurie. Introduction

1. Introduction

The Danish Mesolithic/Neolithic transition is a key topic in archaeology. Why the transition from a hunter-gatherer economy to a primarily farming economy took place has been much debated. Many different factors have been considered as the main propelling reason for that change. These include invasion by farming communities (Brønsted 1962; Horowitz 1973), adoption by the indigenous Mesolithic communities (Jennbert 1985; Rowley-Conwy 1983; 2004), population increase (Petersen 1973), environmental stress (Rowley-Conwy 1984; Milner 2002) and social and cultural change (Clark 1975; Andersen 1989). In Denmark it was c. 500 years from the first archaeological evidence of domesticates and cultivars c. 3950 BC to evidence of complete agricultural adoption in c. 3500 BC with the appearance of forest clearance and the use of domesticated fauna and cultigens becoming the primary mode of subsistence (Price and Gebauer 1992). A more recent debate has been occasioned by the apparent contradiction of stable isotope evidence from Mesolithic and Neolithic human bones, which suggests that the highly marine resource diet of the Mesolithic gave way to an almost exclusively terrestrial resource diet in the Neolithic. However, the continued deposition of shell middens would suggest that marine foods still made a significant contribution to the Neolithic diet (Richards et al. 2003a; 2003b; Hedges 2004; Lidén et al. 2004; Milner et al. 2004; Richards and Schulting 2006).

This article examines the above issues through a detailed study of the common cockle (Cerastoderma edule (L)) from two Danish shell midden sites, Krabbesholm and Norsminde. There are several reasons why cockle shells were chosen for this analysis:

cockle shell is fairly robust and survives well in many archaeological deposits
if the shell gets broken the umbo and beak area can still be used for calculating the minimum number of individuals (MNI) present in archaeological layers
the cockle has a regular growth pattern (see Figure 2) that can be clearly seen in the shell structure which exhibits:
- internal annual and daily growth lines
- external annual growth lines.

The regular growth patterns make it possible to establish two important factors, i) the age of the cockle at death and ii) the season in which the cockle died.

One other reason for cockles being chosen for this analysis was as a complementary study to the seasonality work done by N. Milner (Milner 2002) on oyster shells from Norsminde and her analysis of the oyster shell from Krabbesholm, which was undertaken concurrently with the cockle analysis from that site (Milner and Laurie in press) (see Figures 16 and 18).

The cockle analysis addressed the following three research questions:

To what extent did shellfish consumption change through time?
What evidence is there for changing cockle exploitation through time?
Are there any patterns in the seasonality of cockle exploitation?

Both Krabbesholm and Norsminde middens contain Mesolithic and Neolithic deposits. Before examining the archaeological cockles, modern control samples were obtained over a two-year period from four British locations (see Figure 1). Growth line analysis was undertaken on the modern cockles in order to provide a known standard against which the archaeological cockles could be measured. The acetate peel was chosen as the most appropriate methodology for examining the shell microstructure to investigate cockle seasonality and age. Cockle shell is suitable for this type of analysis as the shell grows in regular, measurable increments, see Figure 2 (Richardson et al. 1979).

Figure 1: Map showing the location of the modern cockle collection sites in Britain

Figure 2: Regular growth markings on the exterior and interior structure of the common cockle

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