An example of bog butter and its wooden container, recovered from Muckanagh, Co. Mayo, and dated to AD 775-895. (IMAGE: National Museum of Ireland)

A study recently published in Scientific Reports, examining examples from across Ireland of what is known as bog butter – waxy deposits found in the peat bogs of Ireland and Scotland (see CA 226) – has demonstrated that this was an unusually long-lived practice, spanning from the Early Bronze Age through to the post-medieval period.

For years, the National Museum of Ireland has worked with Bord Na Móna (the Irish Turf Board) and with private individuals to record and retrieve bog butters found by chance. On this project, they collaborated with a team from the University of Bristol, University College Dublin, Queen’s University Belfast, and University College Cork, carrying out lipid and isotope analysis on 32 samples to assess the composition of the butter, as well as radiocarbon dating to explore the duration of the practice. They found that five Irish samples date to the Early Bronze Age, pushing back the known start of this activity by as much as 1,500 years.

Although the reason why this practice began is still a mystery, in their report the team noted: ‘While the acidic, anaerobic environment of bogs may have been utilised for temporary storage, there are wider patterns of depositional behaviour in the Early Bronze Age to be considered. Strict depositional rules have been observed for gold objects, axes, and specialised bladed weapons; foods are an often-ignored category, but may have also been infused with symbolism.’

By the medieval period, though, this method of storage may have been more for protection than ritual purposes. Butter was frequently used as payment, and there are many textual sources that mention the raiding of butter stores. The team mused that ‘food security must have been an issue for communities, with the storage of butter in bogs perhaps a wise precaution’.

Isotope analysis to assess the composition of the butter also proved enlightening. This found that the bog butters could be confidently identified as ruminant dairy fat – confirming that the substance is indeed butter, something that was not at all certain, as some Scottish examples have been identified as ruminant adipose, or body, fat.

The paper highlighting the results of this study can be read for free at www.nature.com/articles/s41598-019-40975-y.

This article appeared in CA 350.

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