Temporal Trends in Medieval Diet at Stoke Quay, Ipswich, England Eleanor Farber 1 , Alice Rose 2,3 , Julia Lee-Thorp 1 , Louise Loe 2 , Helena Hamerow 4 1 Research Laboratory for Archaeology and the History of Art, University of Oxford; 2 Department of Archaeology, Cambridge University; 3 Burials Department, Oxford Archaeology; 4 InsQtute of Archaeology, University of Oxford Introduc)on Materials Methods Results The decades around AD 1000 saw a marked increase in marine fish consump)on in England 1 , with corresponding increases in fish remains at proto-urban trading centers 2,3 . This trend has also been observed through isotopic and faunal analysis at other loca)ons in medieval Britain, most notably in “elite” cemetery groups 4,5 . However, few isotopic studies have focused on large numbers of individuals at a single site over )me, so it is unclear whether increased marine protein consump)on occurred simultaneously across Britain, or whether the change was more regionally variable. Recent excava)ons at Stoke Quay, Ipswich produced a large skeletal assemblage of 1,162 individuals, reflec)ng 900 years of nearly con)nuous burial prac)ce. As a church cemetery for a middle- to lower-class parish popula)on, this site provides the opportunity to explore large-scale trends and their effects on “average” ci)zens. This pilot study assesses the poten)al for carbon and nitrogen stable isotope analysis of bone collagen to reveal medieval dietary trends at Stoke Quay. Specifically, we examine whether temporal differences in diet can be iden)fied at this site, and if so, whether these differences correspond with the increased marine resource exploita)on observed at contemporary Bri)sh sites. We aimed to obtain a representa)ve sample while including individuals with unusual physical characteris)cs, pathology, or trauma. Other factors were burial loca)on and phase, sex and age. • Ages: 49 adults and 1 adolescent • Sexes: 26 males (M), 19 females (F), 5 indeterminate (?) • Elements sampled: )biae (n=3), mid-thorax, mid-sha^ ribs (n=47) avoiding epiphyses, pathological lesions and trauma Fig. 4 Distribu)on of sampled burials across the site. Fig. 1 Ipswich, England Fig. 2 Stoke Quay, Ipswich Fig. 3 Site plan for Stoke Quay excava)ons (image courtesy of Oxford Archaeology). • 0.5 - 1g bone samples were cleaned using an air-abrasive system with 5 μm aluminum oxide powder, then crushed with an agate mortar and pestle. • Bone collagen was extracted following methods of O’Connell & Hedges 6. • Samples were measured in duplicate. Average values are reported in delta nota)on rela)ve to V-PDB for carbon and AIR for nitrogen. • Isotopic values, C:N molar ra)os, and elemental abundances were calibrated against an in-house alanine standard (traceable to the V-PDB interna)onal standard). • Aliquots of the alanine standard were used to correct for instrumental dri^, and in-house cow and seal collagen standards (traceable to V-PDB via USGS 40 and 41) were used to normalize δ 13 C and δ 15 N data. δ 15 N range: 8.9‰ to 14.9‰ (mean 12.6‰ ±1.3‰, 1σ) δ 13 C range: -20.2‰ to -17.4‰ (mean -18.8‰ ±0.7‰, 1σ)* Fig. 5 Scajerplot of δ 15 N and δ 13 C results for Stoke Quay cemetery group (n=50). Dashed lines indicate group means. 8 9 10 11 12 13 14 15 16 ?¹?N ? -22 -21 -20 -19 -18 -17 -16 ?¹³C ? δ 15 N‰ δ 13 C‰ *All samples met the requirements for collagen preserva)on, with C:N ra)os of 2.9-3.6, and collagen survival over 1% 7,8 . Repeat analysis of the alanine standard (n=25): δ 15 N mean -1.6‰ ±0.2 (expected δ 15 N: -1.6‰), δ 13 C mean -26.9‰ ±0.1 (expected δ 13 C: -27.1‰). Discussion Conclusions Temporal Dietary Trends • Mean values for both δ 15 N and δ 13 C increased over each burial phase, but only δ 13 C values yielded sta)s)cally significant differences. Diet changed most drama)cally between the early/mid-Saxon (Phase 2) to late-Saxon and medieval periods (Phases 4-6). • The highest values in Phase 4 approach those in Phase 6, indica)ng that the shi^ toward increased marine resource consump)on may have begun earlier at Stoke Quay than at other contemporary sites. • δ 13 C results indicate a predominantly terrestrial C 3 diet, as expected for this region, but many individuals also consumed marine proteins, as indicated by their high δ 13 C values. • δ 15 N values are generally higher than expected for a terrestrial C 3 ecosystem; nearly half of the samples yielded δ 15 N values above 13‰, sugges)ng marine resource consump)on. • The Phase 4 isotopic values imply that some individuals at Stoke Quay habitually consumed marine foods before this prac)ce was common elsewhere in Britain. • By Phase 6, marine protein consump)on was widespread, but there was s)ll considerable varia)on between individual diets. • Males yielded the highest isotopic values, indica)ng greater access to marine foods, perhaps due to par)cipa)on in the North Sea trading area. • Throughout Stoke Quay’s use, diet was not uniform or strictly governed by biological sex, but rather varied greatly in terms of terrestrial and marine input. • The high propor)on of individuals at Stoke Quay who likely consumed marine fish suggests that we may need to rethink tradi)onal correla)ons between diet and socioeconomic status. 8 9 10 11 12 13 14 15 16 ?¹?N ? 2 4 5 6 Phase δ 15 N‰ -22 -21 -20 -19 -18 -17 -16 ?¹³C ? 2 4 5 6 Phase Phase δ 13 C‰ 8 9 10 11 12 13 14 15 16 ?¹?N ? ? F M Sex Excluded Rows 1 -21 -20 -19 -18 -17 ?¹³C ? ? F M Sex Fig. 6 Boxplots of δ 15 N by sex. The male group mean is sta)s)cally significantly higher than the means for females (p=0.0189) and individuals of indeterminate sex (p=0.0012) (Tukey- Kramer HSD). Fig. 7 Boxplots of δ 13 C by sex. The male group mean is sta)s)cally significantly higher than the female group mean (p=0.0109), but there is no significant difference between males and individuals of indeterminate sex (Tukey-Kramer HSD). Sex Sex δ 15 N‰ δ 13 C‰ Fig. 8 δ 15 N boxplots by burial phase. There are no sta)s)cally significant differences between burial phases. Fig. 9 δ 13 C boxplots by burial phase. The Phase 2 mean is significantly different from the Phase 5 and 6 means (p=0.0179; p=0.0094) (Tukey-Kramer HSD). 8 9 10 11 12 13 14 15 -21 -20 -19 -18 δ 15 N ‰ δ 13 C ‰ Belle Vue House/Lamel Hill (7th-8th cen) Fishergate (11th-12th cen) All Saints (13-16th cen) All Saints (mid-late 16th cen) Bujermarket Ipswich (6th-8th cen) St. Giles (12th-15th cen) Warrington (13th-17th cen) Towton (15th cen) Berinsfield (5th-7th cen) Stoke Quay Pilot (7th-15th cen) Fig. 10 Site means (±1σ) for Stoke Quay and 9 broadly contemporary sites in England 9-11 . Phase ComparaQve Site Means The Stoke Quay site mean is almost equal to that of 15 th - century Towton, and the 1σ range reaches higher values than at any other site, including “elite” groups. Stoke Quay may have been an usual site for its )me, both in terms of dietary variability and access to marine foods. Typical rib sample Bone collagen extrac)on Weighing samples Mid/late Saxon to post-medieval cemetery Mid Saxon to medieval rubbish pits and latrines Mid/late Saxon post buildings Early Saxon barrow cemetery Mid/late Saxon wells Modern feature Burial Church Phase 2 (6 th -8 th c.) 4 (9 th -10 th c.) 5 (11 th -12 th c.) 6 (12 th -15 th c.) 12 th c. church) • To bejer characterize temporal changes in diet at Stoke Quay: bone collagen δ 15 N and δ 13 C analysis of 300 addi)onal individuals, ages 1-60+, from all burial phases. • To establish an interpre)ve framework for human values: bone collagen δ 15 N and δ 13 C analysis of 200 faunal and 150 fish samples from domes)c and refuse deposits at Stoke Quay. Current/Future Work • To examine temporal shi^s in the number and origins of nonlocal individuals: tooth enamel δ 18 O and 87 Sr/ 86 Sr analysis of 50 individuals selected using bone collagen δ 15 N and δ 13 C results. • To inves)gate the interac)on of health, diet and migra)on: analyze isotopic results in combina)on with skeletal indica)ons of metabolic and infec)ous diseases, and stress.