CHAPTER THIRTEEN Analysis of Lipid Residues in Archaeological Artifacts: Marine Mammal Oil and Cooking Practices in the Arctic C. Solazzo and D. Erhardt
Caroline Solazzo; l aborato ire de Chimie Organique at Macromoleculaire (LCOM ): Universite des Sciences al Technologies de Lille: UFR de Chimie, Bat C4, porte 210: 596 55 Villeneuve d'AsQ Cedex; France
Pottery sherds, stone lamps and artifacts from for lipids and proteins and one individual could feed a archaeological sites in Alaska and Canada were selected fam ily for days. from the arch ives of the National Museum of Natural Hi story in Washington DC. Ancient organic residues Blubber is a thick laycr of fat and connective tissue were collected on th e sherds, often incrusted as a thick located between the skin an d the muscle of marine layer. Lipids we re extracted from th ese residues mammals. Blubber function s as ins ulation and as an foll owed by de ri vatization and analysis by high energy store. It has a eomple.I( structure of fal cells and temperature gas chromatography (BTGC) and combined structural fibers made of collagen and elastin embedded gas chromatography mass spectrometry (GCfM S). in the fat matrix to give it both ri gidity and elasticity. It Modern samples of whales and seals were also analyzed. is a good source or lipids but also provides proteins. Some of these fresh specimens were thennally degraded Lipids composing th e bl ubher arc subject to variation to si mulate cooking and ag in g. Alkaline treatment was and depend directly on the source of food. Stud ies show sometimes necessary to hyd rolyze the insoluble li pid scasonal and geographical variations as well as fraction. composilional diffcrenees by sex, age and stage of pregnancy and lactation (Dahl et al. 2000; Grahl·N ielsen Thousands of years ago, Eskimos sellied on the el al. 2003; Ha milton et al. 2004; Lockyer et al. 1984; American coasts around the Arctic Circle and developed Olson and Grahl·Nielse n 2003; Pabst et at. 1995). The II fascinating culture in onc of the most extreme climates oil rendered from the blubber was also used for fucl ing of the world. I The ancicnt inhabitants of the arctic and lamps (Blumer 1997; Lucier and Vanstone 1991 ; Nelson su b·aretic coas tal areas adapted to an economy rel yin g 1899; Spencer 1959). primarily on the sea. In regions where land mammals are rare and plant resources sparse, mari ne mammals (seals, Cooking Practices In the Arctic Coastal Areas whales and walruses) provide an essential souree of raw The inhabitants of arctic and sub-arctic coastal arcas materials: skins and furs for clothing, boots, kayaks and relied heavi ly on sea mammals (walrus. seals and tent s; bones and ivory for tools, weapons and decorative whales) for their subsistenc\! (Dumond 1998). objec ts; meat and fat for food and fu el. The muscles and Carbohydrates were absent in the diet and had to be bl ubber of large sea mAmm als were important sources compensated for by increased consumption of lipids and proteins. For examp le, ror a fam ily of 10 people with 8 dogs at Poim Barrow, 60 kg of meal were necessary every day (Spencer 1959). Fish, birds and other small The general term Eskimo rerers to all groups games were a complemcnlary source of food, as well as inhAbiting th e Arctic and Sub-arctic regions rrom North roots, berries and seaweeds. Cari bou was hun ted when Eastern Siberia to Greenland. With the Aleuts, 8vai lable, bUI thi s could only be found inland and the occupying th e Aleutian Islands, they fonn th e Eskimo migration patterns of caribou arc more unpred ictable Ale ut fam ily from which are de rived the different than those of the sea mammals. language groups: Aleu t in the Aleutian Islands, Yupik in Eastern Siberia and Southwestern Alaska, and Inupiaq· In Alaska, wooden di shes were used to store water, oil or Inuktitu!. a continuum of dialects spoken from Ihe coasts fcnnented food (mi xt ures of meat, fal and berries); fish of Northcrn Alaska and Canada \0 Labrador and and meat coul d thcn be ealcn rftW, dipped in oil. Food Greenland. Inuit is the term in use for ArClie pop ul ations was cooked by boiling or simmcring, usually with oil in Canada and Greenland. Solazzo and Erhardt: Marine Mammal Oil and Cooking Practices in the Arctic
rendered from blubbcr, in cia), vessels to make stews and soups. Meat and fish were also roasted on an open fire when wood was available, or eaten frozen, dried or aged. 'Muktuk'. a mix of skin and blubber th at was consumed raw or cooked and that apparent ly tasted likc coconut, was caten with relish (Geist and Rainey 1936; Nclson 1899; Spencer 1959). Cooking by means of hot stones was practiced at Barrow (Reid 1990) and in southern Alaska (De Laguna \956).
Open oil-burn ing lamps were an important utensil in daily life. Oil rendered from blu bber provided fuel for Ihe lamp. Made of clay or soapstone, the flat·bottom lamps were used for li ghting, heating and cooking. On S1. Lawrence Island a second pOI fashioned of clay was hung above the lamp and uscd as a cooking po\. Anot her clay or wooden pot. in the shape of the lamp, could be placed und er the wick to collect any dripping of oil (Collins 1937; Nelson 1899).
Oil.burning lamps wcrc rcproduced in the laboratory. Blubbcr was cut in 2 x 2 em squares, placed in a modern clay sauccr and lit with a straw wick. The blubbcr rendered oi l and provided a constant flame for up to IWO hours (using about 10 ml of oil). A small cup was placed 5 em abovc the lamp with 20 ml of water. The heat from thc lamp was sufficient for the walcr to simmer but not to boil.
Figure 1. Examples of artifacts from wh ich residues were laken. From top to bollom: saucer-shaped clay lamps numbers 382643 and 382644 from Nunivak Island, pOlS herds from Miyowagh on SI. lawrence Island, soapstone lamp number 365447 from Kodiak Island and wooden dish number 342583 from the vicinity of Wales.
2 Theory and Practice of Archaeological Residue Analysis
The Artifacts ncar Ga mbell in th e northwcstcrn pan of the SI. Pottery was developed in Alaska and western Canada as Lllwrcnce Island.1 Mi yowagh is the second mosl ancient early as 1500 BCE and persisted until European contact village al Gambell and datcs back from the Old Bering and th e histori c period. Aretic pottery is made of a Sea culture lind thc beginning of the Pu nuk. At this timc. coarse black paste tempered wi th mineral or organic the hunting of wa lrus and seals was well dcveloped; mate ri als, depending on their availabi lity. It is described whalcs were obtained from stranded animals (Collins as thick, crude and briltle. As it cru mbles easily few 1937). 51. Lawrence Island is si tuated at 63°N in the complete vessels have been found. They were generally Bering Sea, about 150 km (100 miles) from the coast of nat bottomed containcrs with thick wa ll s and wide Alaska and 60 km (40 mil es) from Siberi a. The openings, compared to the size of th e pot. Usually, oit terrestrial fauna is rcstricted to arctic foxes, arctic lamps were shallow with thick walis, wh il e cooking pots squirrels lind somctimes polar bears; the is land is often we re deeper and had th inner wa ll s. Dccorations arc very frequented by birds. Because of its isolated location (SI. rare (Ackerman 1961; Collins 1937; De Lagu na 1947; Lawrcnce Island is encirc lcd by thc icc more than ha lf Geist and Rainey 1936; Reid 1990; Spencer 1959; the year) the in habitant s rc licd esscntially on ma rine Stim mel and Stromberg 1986). Dcach gravel was used as animals for subsistencc; whalcs, sca ls and in particular a mi neral temper and could make up as much as 50% of walrus, abundant in the north of the island (Co ll ins 1933; the paste. Ma rine mammal blood and blubber were 1937; Dumond 1998; Geist and Rainey 1936). sometimes ad ded \0 the temper. Fiber temper (animal hair. grass, wood, feathe rs and baleen) WIlS responsible Twelve clay sherds. eight stone lamps and tools, one for the high porosity. Ceram ics could be coated wi th wooden di sh and one bonc scraper from the coast of burned grease and fat on both sides, scaling the pores Alaska between Point Barrow and the Aleutian Islands before each usc. The limited avai lability of wood were also sampled. At 71 °N Point Barrow is the restricted the firing to low temperatures. These types of northernmost point of Alaskll, protruding into thc vessels arc good insulators, making them suitable for Beaufort Sea. St. Law rcnee Island and Poi nt Barrow aTC simmeri ng, stewin g or the rendering of oil by stone located along sea lIIam lllal mi gration routes and arc st ill boiling (Reid 1990). act ive whaling villages. Coastal Eskimos would hunt along the shore, chieny in sea rch of bowhead whales No pottery was manufactured in the Aleutian Islands. lis during their spring migration (Spencer 1959). The absence is due to the lack of suitable clay and th e Aleutian Islands arc si tuated west or Alaska. Thc abundance of easily carved volcanic rock (McCartney archipelago consists of about 100 islands spread out over 1970). The lamps havc th ick wa ll s and arc ovoid, 1450 km (900 miles). The water around the islands is narrowing at one end where the wick was placed particularly rich in sea mammals attracted by the mi lder (DeLaguna 1956; Laughlin 1980). Figure I presents a weather (La ughlin 1980). The other localities from few of the artifacts chosen for analysis. which samples werc investigated include the Seward Peninsula, Norton Sound, Nunivllk Island and Kodiak Archaeologicnl residues were coll ected from arti facts Island (Figure 2, Table I). excavated in Alas ka and Canada and kepI by th e National Museum of Natural Hi story of the Smithson ian As described in th e avai lable archaeological litcrature Institution. (lecause of their geographical contcxt it is the clay potsherds wcrc made from a coarse and crudc fairly certain that thc ccramic pots and the soapstone paste. The walls of the vesscls varied from 0.5 to 2.7 cm lamps must havc containcd primarily marine products. and the surfaces wcre smoothed and undecorated. Most Li pids analysis was eonductcd using chromatographic of thc vessels had a high porosity and were ccrtainly techniques. Lipids usually survive well in archacological subjected to low temperature firing. Thcy wcre tempered contexts because of their hydrophobic natu re. The with mi ncral and vcgetal mailer likc grass, feathers and conservalion or fally acids appcarcd particularly maybe mammal hair (Coll ins 1937; Oswalt 1955). Thesc enhanced by the specific condit ions of the Arctic. The sherds preserved amorphous organic rcsidues on the composition of the fatty acid profi le rcsulting from inner or the outer surfacc, or bot h. In thc lallc r case both hydrolyzed and ox idi zcd acylgyceridcs, obscrved aner sides wcre sampled when possiblc. The residues on thc processing and burial of fats and oils, was charactcrized. potsherds were th ick, ca rbonized deposits. Two shcrds Biomarkers, such as products of the oxidation of (U I and SL6) did not have 8 visible rcsiduc. In thesc cholestcrol and isoprcnoid acids, werc also obscrved. cases the en ti re sherds were ground and any absorbed organic residue extracted. The stone lamps contained a Archaeological Samples thin laycr of residue, strongly adhering to the surface. Archaeological soapstone lamps from Canada as well as clay, wooden and stone artiracts from archaeological si tes in Alaska were examined for the presence of lipids. Thc name Miyowagh was in troduced by Collins A series of 18 sherds, between 1000 and 1500 years old, (1937), other designations includc MayughlVaaq (Badtcn wcre selected from the IIrchacological site of Miyowagh et a1. 1987) and Miyowaghameet (Coll ins 1932).
3 Solazzo and Erhardt: Marine Mammal Oil and Cooking Practices in the Arctic
Arctic Ocean / '" Greenland
\ \
SILawrence Island
Canada
Berin g Sea
Aleutian Islands rn Permanent Ice E..~J fce NO V. -June • • •>Jt:i'..r.:= , 400km U 50% 1<,
Figure 2: Maps showing the archaeological sites and provenance of the artifacts sampled in Alaska and Canada.
Three olher objects were also sampled: a Slone 'bola' o f the Inuit in Arctic Canada, began using soapstone (used to kill seals), a wooden dish and a bone scraper. lamps an d pots about 1000 to 500 [leE. The first two were covered with a thick layer of decomposing fat, still fresh and mixed with grass in the The samples from SI. Lawrence Island were excavated in dish. The bone scraper was covered wilh a black material 1930 and 1931 by Collins (193 7); the other samplcs that provcd difficult to remove. Three additional samples from Alaska were collected in the first half of the 20'" wcre takcn from soapstone vessels excavated at Adlavik century CE for the National Muscum of Naturall-listory 1·larbour. a coastallnuil community (dated to about 1750 and werc stored at the Smithsonian Institution, most CE) in Labrador al 55°N. The samples lVere of a brown recently in an environment-controlled storage area. The waxy material. The Thule people. who arc the ancestors samples from Labrador were uneanhed between 1999
4 Theory and Practice of Archaeological Residue Analysis and 2004 and were stored in plastic bags and wooden anthropological data. Samples were taken from the drawers at the Smithsonian Arctic Studies Center. blubber of a Phoca hlspida (ringed sea l), provided by the National Zoo of Washington DC; from the blubber, meat Modern Specimens and skin of a Phoca vitl/lina (harbour seal) and a Some species that aTe traditionally hunted, or otherwise Halichoerus grypus (grey seal), hunted in Canada in obtained, by the Eskimos were studied as referencc. 2005 and provided by the Vertebrate Zoology These included ringed seal, harbour seal, grey seal, Department of the National Museum of Natural ~Ii s t ory; beluga whale and nanvhal (narwhal and grey seal are from the blubber and skin of th e neck of a male native to eastern Canada). In order to compare these Delphinapterus leucas (beluga whale) from the Churchill fresh specimens with the archaeological samples they River (Manitoba, Canada) and conserved at the were subjected to high temperature storage to reproduce Smithsonian Institu tion; and from the blubber near the aging. By analyzing cooking residues from Arctic ca r of a female Monodon monoceros (narwhal) stranded archaeological contexts thc degradation of organic in Alaska in 2005. All sa mples were stored frozen. compounds resulting from the processing of foodstuffs can be understood and correlated with the
Sample location on the excavation site Material Remarks Flat, thick with a rim. sand 352986 Miyowagh Cut 1M Section 6 Clay potsherd and aravel temoered 353010 Miyowagh (no information) Clay potsherd Slightly curved, thick Slightly curved with a low 353036 Miyowagh Cut 1M Section 8 Clay potsherd curved wall Flat, thick, sand and gravel 353109 Mlyowagh Cut 2M Section 4 Clay potsherd tempered 353140-1 Mi owaQh Cut 2M Section 6 Clav potsherd Curved, thick Curved, thlcJ<, shaped as a 353140·2 Miyowagh Cut 2M Section 6 Clay potsherd saucer, sand and gravel tempered Flat, th ick with a low, 353197 Miyowagh Cut 3M Section 4 Clay potsherd curved wall (rim), sand and gravel tempered Slightly curved, thick, sand 353233-1 Miyowagh Cut 3M Section 7 Clay potsherd and aravel tempered Slightly curved, thick, sa nd 353233-2 Miyowagh Cut 3M Section 7 Clay potsherd and aravel temoered Flat, th ick, sand and gravel 353274 Miyowagh CuI 3M Section 10 Clay potsherd tempered 353356 Miyowaah Cut4M Section 5 Clay potsherd SIiQhtly curved. thick 353917 MlyowaQh Cut 11 M Section 5 Clav potsherd Flat. thick 353961 Mivawaah Ftoors 1, 2, Cuts 8,11 ,13 Clav potsherd Flat, thlclt Flat, thick with a curved Miyowagh above rool timbers of entrance 354168 Clay potsherd and low wan, sand and to House B, Cut 15M, Section 5 I aravel tempered Miyowagh Cut 9(a), Cache site Easl of 354380 Clay potsherd Slightly curved, th in House B, below level of House B U1-U5 Miyowagh Clay potsherds -- Curved, thin rim, sand and 346426 Cape Kialegak, SI. lawrence Island Clay potsherd I gravel tempered Seward Peninsula Kowieruk, 3 miles east Curved, thin rim, sand, 347878 Clay pOlsherd of Imaruk Basin I aravel and arass temp.!!red Seward Peninsula Kowleruk, 3 miles east Curved, thin rim, sand, 347888 Clay potsherd o! Imaruk Basin I aravel and Qrass tempered
5 Solazzo and Erhardt: Marine Mammal Oil and Cooking Practices in the Arctic
Curved, thin, sand, gravel 372145 Whale Islafld, St Michael, NOrtOfl Sound Clay potsherd and Qrass tempered Curved, thin rim, sand, 351087 Kuskokwim River Clay potsherd gravel and grass temp"ered 382643 Old Eskimo burials on Nunivak Island Earthenware lamp I bowl Diameter 22 em, thick 382644 Old Eskimo burials on Nunivak Island Earthenware lamp I bowl Diameter 22 em, thick Thick, big pot with high 382645 Nunivak Island, Old Eskimo burials Clay potsherd walls 'Our site', Jones poinl, Uyak Bay, Kodiak 365447 Stone lamp 14 x 10cm Island 'Our point', village site Ofl Uyak Bay, 377630 Stone lamp 19x15cm Kodiak Island Atka Island, Andreanof group, Aleutian 390463 Stone lamp 15x 13cm Islands Atka Island, Andreanof group, Aleutian 390464 Stone lamp fragment 20x12cm Islands 'Site C', east end of Sweeper Cove, North Flat slab 390569 of road (shell and bone heap), Adak Island, Hearth stone fragment 21 x g cm Aleutians Andreanof Qroup Amaknak Island, northeast end of 395750 Stone lamp 19x16cm Unalaska, Fox Island, Aleutians Qroup Curved thick wall with 396014 Umnak P-A Fox Island group Stone vessel fragment beginning of bottom Wainwright MiUiktavik site, 22 miles 45 x 25 cm, crystals and 342583 Wooden dish northeast of Wales mass From a locality in the southern part of 400347 Bone kayak bailer-scraper Utkiavik Point Barrow, purchased --- From a place in south end of Utkiavik, 400399 Stone bolas Diameter 7 em Point Barrow, purchased Piginik (Barrow Birnick site), Mound J, cut Curved, thick, sand and 399580 Clay potsherd 1 southwest corner of house A aravet temaered Nunagiak (Barrow Nunakiat?), above Curved, thick, sand and 400932 Clay potsherd house X araveltempered SChool Collection, from Poinl Barrow, SL6 Clay potsherd Rim, gravel tempered Alaska Soapstone (steatite) body SL1 Adlavik Harbour-1 House-! Unit 29 vessel sherd, appears to be a --- lamD fragment Soapstone (steatite ) body Adlavik HarbDur-l House- 1 Test-Pit#2 SL2 vessel sherd, vessel type Cul#2 --- indeterminable Soapstone (steatite) body SLl Adlavik Harbour-1 House-1 Unit 3a vessel sherd, side of a large --- cooking kettle
Table 1 (on this and the previous page): Description of the collection of artifacts sampled for analysis.
Because archaeological sa mples have suffered severe ceramic is to store them at high temperatures as heat conditions through time, it is necessary to tl)' and aecelerates the oxidation process (Copley et aJ. 2005; reproduce an artificial degradation of fresh samples. Malainey et al. 1999a; b). Samples o f sea l and w hale Cooking pots arc exposed to hea t during their usc and products in modem clay saucers were artificially aged in modifications of organic molecules will also occur an oven at an average te mperature of 1000C (Patrick et during the long-term burial of the artifacts. The usual al. 1985). A few grams of blubber and meat were boiled method for reproducing the degradation of foodstuffs in w ith water in sauce rs for two hours at 1000C and left in
6 Theory and Practice of Archaeological Residue Analysis the oven for several weeks. Residues were sampled each Alkaline treatment of the fres h sampl cs allowed wee k. The saucer that contained meat of beluga whale identifica tion of the saturated fally acids as their was eut in pieces and one of them was ground and trimethylsilylester derivatives. The fatty acids and thei r treated as the ancient samples. relative proportions for the studied seal and whale species arc presented in Table 2. Fish oil and blubbcr are Analytical Methods ri ch in unsaturated fatty acids. characteri stic of their
Fatty acid standards, n-tetratriacontane (CH H1Q) and the marine origin (Morgan 1983). Eicosapentaenoic acid derivati zation agent N,Q·bis(trimethylsilyl)lrinuoro (EPA, C20:5oo3) and doeosahexaenoic acid (DIM, acetamide (BSTFA), containing 1% tri methyl. C22:6 7 Solazzo and Erhardt: Marine Mammal Oil and Cooking Practices in the Arctic Ringed Grey seal Harbor seal Ringed Grey seal Harbor seal seal Compound blubber blubber seal blubber blubber blubber (12 days) (50 days) blubber (1 days) C8:0 0. 124 0.061 -- 0.205 -- -- C9:0 0.290 0.074 -- 0.245 - - C10:0 0.184 0.085 -- 0.202 -- - C11:0 ------0.541 -- - C12:0 0.508 0.118 -- 0.553 -- -- C13:0 ------1.392 1.018 C14:0 16.968 9.617 5.156 10.286 2.297 4.609 C15:0 -- 0.971 0.327 1.201 0.400 1.302 C16;O 31.462 11 .556 14.458 27.683 3.759 11 .2 18 C11:0 ------1.357 0.541 1.072 C18:0 2.378 0.533 1.558 6.876 1.565 6.617 C20:0 -- 3.949 -- - 0.665 - C14;1 1.949 2.078 2.495 1.535 2.485 1.814 C16:1 4.481 17.588 34 .823 17.760 21.048 25.939 C1S:1 (009) 10.794 31.302 36.667 16.762 27.5 1 24.060 C1S:l (007) ------3.051 11 .253 C20:1 10.160 11 .866 2.213 5.549 6.615 8.343 C22:1 4.073 5.345 -- 1.462 0.715 1.316 C24;1 -- -- - 0.240 -- -- C20:4 1.529 0.670 ------C20;S 7.824 1.282 2.243 -- 10.796 0.288 C22:S 2.496 0.247 -- -- 5.243 -- C22:6 2.928 0.440 -- -- 13.302 -- C4 diacid ------0.932 -- -- C5 diacid 0.449 0.234 -- 0.269 -- -- C6 diacid -- 0.117 -- 0.284 -- -- C1 diacid 0.652 0.210 - 0.383 -- 0.724 C8 diacid -- 0.216 - 0.841 -- 0.366 C9 dlacld 0.745 1.317 -- 0.756 -- -- Total diaclds 1.846 2.154 -- 3.465 -- 1.090 Total monounsaturated 31.457 76.258 41.773 faHyac ids 68.179 52.813 72.785 PIS ratio 13.226 2.926 9.217 4.026 2.401 1.695 8 Theory and Practice of Archaeological Residue Ana lysis Beluga Beluga Beluga NalWhal Beluga NalWhal whale whale whale Archaeological Compound blubber whale blubber blubber blubber blubber samples (50 days) blubber (1 day) (7 days) (90 days) C8 :0 -- 0.557 -- -- 0.973 0.777 O Table 2 (on th is and the previous page): Relative percentage composilion of fatty acids in marine mammal blubber after simulated decomposition; in th e la sl column Ihe range Is given of the fatty acids found in the archaeological samples (A). Diacids are dicarboxyllc fally acids; PIS ratio = C16:01C 18:0. 9 Solazzo and Erhardt: Marine Mammal 011 and Cooking Practices In the Arctic In the aged samples of bel uga whale, the fomllltion of Cooking or burning of the fat has probably occurred diaeids is clearly th e resu lt of th e dcgradation of repeatedl),. Tests in our laboratory re prod ucing a po l yu n ~tura t ed fa lly acids. Although the blubber·burning lamp showed that the heal above the polyunsaturated fally acids quick ly decompose, in 24 flame reached a tempcraturc o f aboll! 200°C. Although hours. diacids appcar only after 7 days at 10o-C. The some contamination may occur from the surroundings profile observed at 24 hours is an intermediate between after immediate discarding, the high concentration of the begin ning of decomposition and its final stage. polyunsaturated fatty aci ds in marine fat arc certainly Before 7 days. diaeids must be present only as their, responsible for most diacids. The conditions of partially oxidized. precursors still allached to the preservation of thc archaeological samples in permafrost glycerol molecule. can provide an explanation for thc excellent recovery of diacids, preventing them from leaching into the soil. The The PIS rat io (C I6:0/CI8:0) can be an indicator to PIS ratio in all archaeological samp les is lower than in discriminatc between catcgorics of residues. The ra ti o the fresh mammal samples, but si milar to the degraded calculated from thc modem sample of beluga whale is samples (Tables 2 and 3). The process of degrading relatively high. more than 11 . It progressively decreascs mammal blubbcr by heating appears to lower th is ratio to with the timc of exposure to heat to reach a value of 3.6 reach abo ut the same value as the archaeological after 7 days at 100"C and seems to stabilize aftcr thaI. In residues. all specics, this ratio decreases to valucs between 1.7 and 4.0. Although a general pattern was observcd, it is not GC/MS Results of the Archaeological Samples possiblc to disti nguish between species. or even between When possible, samples were also analyzed by GC/MS. seals and whales. Basicall y th e same profile WII S Diaeids were observed ranging from 4 to 14 carbon obtained for all kinds of marine oils ond fats. Other atoms and saturated fatty acids from C6:0 to CI8:0, and species, such os walrus, should be tested and added to in some cases also C20:0 Rnd C22:0. Even and odd this study. middle·chain fally ac ids werc also present, mostly C6:0 to C I3:0. C IS:O and C ]7:0, present in small quantities in HTGC Results of the Archaeological Samples animal and ma rine mmnmal fat, were also detccted. The In the archaeolo gical samples polyunsaturated fally acids short- and middle-chain fatt), acids may result from the and TAGs appeared to have degraded. DAGs were rarcly oxidation of unsaturated long-chain fallY ac ids. For detected, but monoacylglycerides (MAGs), such as instance, C9:0 is a product of the ox idative scission of monopalmitin and monostearin, were encountcred oleic ac id. A few oxidation products were identified by frequently. High amounts of glycerol were found in GC/MS: 2-hydroxydccanoic acid. 3·hydroxydecanoic many samples. Its presence indicates hydrol ysis over acid and 12-hydroxyoctadecanoic acid. 12- time. Monounsaturated fally acids with an even carbon hydroxyoctadecanoic aci d is fonncd from chain from 14 to 22, and sometimes 24. were de tectcd. monounsaturated fallY acids with the doublc bond in Although the gas chromatographic method used docs not position II , such as gondoic acid or cetoleic acid. Both separate gadoleic from gondoic acid, or erucic from arc prese nt in lip ids from marine mammals after cctoleic acid, thc pre se nce of long·chain oxidation and dchydrat ion. monounsaturated fatty acids must be considered evidence fo r a marinc origin. Phytanic acid (3,7, II, 15·tctramcthyl.hexadecanoic ac id ) was al so cneountercd (Table 3). This compound is found The observed degradati on of the lipids in frcsh in fish and marine mammals and it could be an important specimens demonstrated that polyunsaturatcd fatty acids biomarkcr. Two other isoprcnoid falty ac ids arc can oxidize in a couplc of hours at lowe or highcr. and considered charactcristic of oils from marine mammals: in a cou ple o f days at lower temperaturcs. This is 4.8. 12- trimethylt ridecanoic acid (TMTD) and pristanic followed by Ihe formation of diacids. These were found acid (2.6, I 0, 14·tetramethylpentadecanoic acid). Allthrce in abundanc e in all Ilrchaeological samples. The profile are proposed to comc from the phytoplankton and kri ll of diacids was si mil ar in most samples, ranging from ingested by marinc mommAls (Ac kman 1968; 1989; 4· 14 carbon atoms with azelaic acid (C9 diacid) Ihe most Hansen 1970). These isoprcnoid compounds arc found in abundant. A7..c laie ae id is the primary degradation higher concentrations in marine tha n in terrestria l product in mammal fat. due to Ihe abundance of C18: 1. animAls. Their detection in pots can be uscd as a good C 18 :2 and C I6 : 1. Longe r chain diaeids arc from the biomarkcr to prove the prcsence of a marine sou rce of degradation of long-chain monounsaturated fatty acids. food , especially whale oil (Hanse n 1970). i'ristanic acid such as C20:1 and C22:1, also abundant in ma ri nc and TMTD hllve been detected in only a few samples, mammal fill. Oxidizing conditions or high temperatures whi ch may be duc to the no turally higher abundancc of are responsible for the clcavagc of the double bond in phytanic acid (Copley ct a1. 2005). Cholesterol has been unsaturated fatt), acids (Colombini ct al. 200S: Copley et detected. as well as two of its oxidation products: al. 2005; Regert 1998). cholesta-3,S-dicn-7-one and cholest-S-en· 7·onc. 10 Theory and Practice of ArchaeologIcal Residue Analysis Cholesta-3,S-dien-7-one is known to be thermally average of 22% of all fatty acids, varied between 35% in derived from 7-ketocholcsterol. whi ch is often the main sample 3S4380-2(E) and 9%, 10% and 12% in samples product of auto-oxidation of cholesterol (Rose-Salin 353961(1), U3(1) and U5(E) respectively. Stearic acid 1996). It has been shown that the auto-oxidation of had an average relative abundance of 7% and appeared polyunsaturated TAGs accelcrates the oxidation of more co nsistent among the samples tested. In the last cholesterol (K im and Nawar 1991; Osada ct al. 1993). column of Table 2 the ranges of pe rcentages of fatty These unstable compounds are quickly oxidized and acids found in all archaeological samples (A) is produce radicals that accelerate the oxidation of presented and compared to those found in sea mammals. cho le sterol (peroxidation of th e TAGs by heating). The PIS ratios varied littl e, from 1.2 to 4 with an average The Samples from Mlyowagh value of 2.9, a range typical of mammal fat. Only Archaeological residues from Miyowagh, St. Lawrence 353274 has a relatively high ratio of 7.2. MAGs were Island, are probably the oldest samples analyzed in th is detected in all bu t three samples. When present, study. They were found in kitchen middens from a I sao monostearin was the main MAG, usually accompanied yea r old site on a gravel beach. Residues are by mono-olein. Monopalmitin was sometim es identified characterized by monounsaturated fatty acids, especially by HTGC, but can be eonfused wi th C22: 1. GCIMS is monounsaturated fatty acids with 20 carbon atoms, more sensitive and allows the id entification and gadoleic acid (C20: 1(09) and gondoic acid (C20: I 00 II); separation of monopalmitin and monomyristin. When and with 22 earbon atoms, crucic ac id (C22: I 009) and comparing all ceramics sampled on both interior and eetoleie aeid (C22: 100 11). A variable amount of C22:1 exterior, 3539 17, 35396 1, 354380·1, U2 and U3 have was prese nt, with an average of 4.5% of the total more degraded organic residues towards the inside composition in fally acids. C20: I was quitc abundant. (Table 4). These results corroborate the assumption that from 5% to 10% of all fatty acids. Only two samples had these sherds are from oil-burning lamps. The oil burning low levels orC20:1 (3S4380-2(E) and 353274), these did formed a layer of aeeumulated soot exposed to repeated not contain C22: 1. C18: 1 varied from 7% to 14%. heating. The residues found on the exterior were either Palmitoleic acid, C16:1 was present at a maximum of spilled from inside the lamp or appl ied to create a 8% of all fatty acids. C 16: I is less stable than C 18: 1 and waterproof coating. This fat was certainly exposed to a during degradation its quantity is more likely to decrease less intense heat. and palmitoleic acid will disappear first. CI6:0, with an Mono Mono Iso- PIS Sample Mass (g) Glycerol acy l- unsaturated Dlaclds prenold Sterols ratio glycerides fatty acids acids Miyowagh, Gambel/, 51. Lewrence Islend 352986 I 0.011 8.311 3.614 26.111 16.264 1.889 353010 E 0.100 0.239 2.109 32.636 7.091 · · 2.919 353036 I 0.019 6.100 6.213 24.051 17.29 2.468 353109 E 0.152 4.353 0.609 25.996 20.134 2.586 353140-1 E 0.163 3.78 1 3.392 36.707 10.853 · · 2.847 35314\0-2 E 0.152 10.188 5.416 24.515 21 .200 · · 2.557 353197 E 0.159 5.776 3.331 39.672 10.338 2.602 353233-1 E 0.152 12 .554 4.552 31 .809 10.997 · · 2.856 353233-2 E 0.150 4\ .553 5.082 33.274 14 .037 · · 2.768 353274 E 0.152 19.916 0 5.238 17 .053 7.163 353356 E 0.157 5.664 2.988 34.898 10.886 3.616 353917 E 0.150 3.976 0.670 30.991 11 .997 3.268 353917 I 0.052 4\ .251 0.090 21 .768 22.14\0 4.042 353961 E 0.152 4\ .338 8.348 28.663 13.408 · · 3.154 353961 I 0.026 13.632 1.643 15.262 31 .813 1.223 354168 E 0.153 3.944 3.550 30.884 14 .465 · · 3.207 354380-1 E 0.150 4.008 2.556 28.365 14 .908 3.280 354380-1 I 0.050 5.280 4.309 26.59 24.167 2.885 11 Solazzo and Erhardt: Marine Mammal Oil and Cooking Practices in the Arctic 354380-2 E 0.081 2,316 0 12.936 12.195 3.277 354380-2 I 0.108 2.314 3.340 23.692 13.1 44 3.122 U1 2,307 Ceramic 0.948 1.842 18.556 17.829 2.959 U2E 0. 165 4.441 1.219 29.739 17,05 1 · · 3.748 U2I 0.101 4,917 0 24.999 29,151 3.898 U3 E 0.154 4,120 4.786 34.268 14 ,537 · · 2.671 U3I 0.100 10.765 5.785 24.167 24.466 1.818 U4E 0.150 6.096 1.817 23.177 10.548 • · 3.672 USE 0.153 2.115 2.1 97 24.114 31 .911 · · 1.954 Kialegak, SI. Lawrence Island 346426 CLAY 0,040 2.038 0 44.443 11 .304 · · 2.409 Seward Peninsula 347878 CLAY 0.035 12.146 2.881 29.073 16.1 16 · · 2.222 347888 CLAY 0.100 10.717 6.786 25.486 18.778 · · 3.252 372145 CLAY 0.042 7.865 11.478 35.659 7.982 · · 2.116 Kuskokwim River 351087S1 CLAY 0.100 6.989 4.307 36.971 9.810 · · 2.176 351087S2 CLAY 0.104 10.139 2.335 28.465 11 .390 2,817 Nunivak Island 382643 CLAY 0,093 11.447 3.236 14.997 31.535 · · 3.782 382644 CLAY 0.090 19.159 0,925 29.475 17.948 · · 3.720 382645 CLAY 0. 145 11.983 8.152 30.546 12.651 · · 2.636 Kodiak Island 365447 0.034 7.871 STONE 36.217 16.507 6.042 · · 2.769 377630 STONE 0.033 7.710 13.2 20.689 10.425 · · 3.272 Aleutian Islands 390463 0.019 4.128 18.293 19.579 7.524 STO NE · · 3.260 390464 0.060 33.157 STONE 0 18.052 10.282 3.603 390569 0. 11 3 0.676 12.138 STO NE 20.232 16.354 · · 1.381 395750 0.033 10.713 35.237 14.863 4.904 2,1 96 STO NE 396014 STONE 0.093 0.697 3.038 18.738 4,846 · · 4.46 12 Theory and Practice of Archaeological Residue Analysis Northern Alaska 342583 0.023 1.335 4.875 WOOD 41 .473 10.293 - - 7.646 Point Barrow 400347 WOOD 0.034 1.344 28.859 11 .754 42.883 · - 1.605 400399 0.778 • STONE 0.030 5.384 11.831 27 .339 - 3.1 49 399580 0.100 5.104 21 .640 31.925 8.734 2.415 CLAY 400932 0.100 2.744 7.062 26.67 10.620 1.506 CLAY - - Sl6 . CLAY 0.156 1.106 2.750 25.062 4.979 • 2.552 AdlBVik Harbour Sl1 0.150 11 .029 8.018 24.752 STONE 19.715 2.282 S12 0.150 12.983 13.603 STONE 42.984 3.285 2.572 SL3E 0.150 11.1 13 30.404 13 .927 17 .080 t .198 STONE SL31 . STONE 0.150 11 .835 13.719 23 .212 14 .354 · 1.721 Table 3 (above and on the previous pages): Fatty acid promes of the archaeological samples. Glycerol, monoacylglycerides, monounsaturated fatty acids, diaclds and the PIS-ratio (C18:0ICI8:0) we re calculated from HTGC data. The values indicate the relat ive percentages calculated from the sum of all detected fatty acids. Isoprenoid acids and sterols (chotesterol and products of oxidation) were positlvely detected (0) or not (-) by GCIMS (blanks indicate that GC1M$ was not performed). DAGs werc found in only \wo samples from St. 382643 from Nunivak only had 14.7% unsaturated fauy Lawrence Island. U5 containcd diacids, mostly C8 11IId acids. bu t marc than 30% diacids. Independent of their C9, with reduccd amo unts of monounsaturated fatty gcographical provenance, all clay vessels have th e same acids, C 16:0 and CI8:0. Bccause the hydrolysis of the fatty acids profile. and the slight differences can be DAGs was incomplete. monounsaturated fatty acids and explained by a more or less advanced degradation or C14:0, C16:0 ond C18:0 arc less abundant as frec fatty sli ght differences in the initial lipid composition. The acids. It seems that the decomposition of the rcsiduc is latter can be due to the species or the feed ing period. less advanced; this vessel may have been used to collect factors thaI can not be aecounled for by this kind of dripping oil instead of being used as a cooking pot or a ana lysis. lamp. Samples from slone artifacts from the Aleutian Islands Artifacts from the Coasts of Alaska arc disti nguished from the samples of clay art ifacts as The artifacts from coastal archaeological sites in Alaska they have much less CI8 :1, C16: 1 and diaeids while were classified accord ing to their geographic origin and MAGs are ab undunt. Possibl y. res idue s have less their material (clay, stone, wood or bone). IlTGC adherence on stone and some components may leach out chromatograms o f a clay potsherd (399580) and the bone more easi ly, especially in the milder climate of the scraper (400347) arc shown in Figures 3b and 3c, Aleutian Island s. Anothcr possibility is that the oil used GC/MS chromatograms of a soapstone lamp (SL3), the on the Aleutian blond comes from different marine bola (400399) Hnd the wooden dish (342583) arc shown mammals tha n further north. Howcvc r. the PIS ratio is in Fi gu res 3d, e and f. Samples from ceramics fou nd at normnl for a mn rine source with an ave rage 3.26. Fi gure Kialegak. Seward Peninsula. Kuskokwim Ri ver, 4 shows the percentage of monoun saturated fatty nc ids Nun ivak Island and Point Barrow had a composit ion plotted ogainst the percentage of diacids in these similar to the samples described above. On avcrage, the arti facts. PIS ratio is 2.6. One sample seems 10 be more degraded: 13 Solazzo and Erhardt: Marine Mammal Oil and Cooking Practices In the Arctic " ro o 38 - Beluga whale ,,~ -v , ~ ., , .v ,, ~ v , ~ ~ ~ ~ " '00 G ••"< ~ ," .E ,w , "v , ", o ~ ., ~ " " ,~ W& .~LIT i~,~ " 'O~ "' Retention time (min) '" 3b-399580 before saponlflcatfon ro, Ii after saponification » Retention'" time (m" in) Figure 3a and 3b: High temperature gas chromatograms of Beluga whale blubber (a) and clay potsherd 399580 (b). 14 Theory and Practice of Archaeological Residue Analysis i , i i i i , , • • • • • • ,i • •i •i .•. .• o f-- --- ' " - ·-- DU "n mono~ lmlli n ~ I- mono-ol.'n r-- monO".lfrln , , Inlln,lly pA /n/.",'I)' pA • •jj •'" • ; il!~.J. ,• ' iE~:;;:. =='=~=,=':--·'-- ·~'C' --,-' • o ~ . ., 11;...,---"":·:...· J. - - - ,H I OJ' • r '""llf 11 '"-~"~'~"======[~'~> " ____-"O '"19'- '" • I ° C18;' (n·!llnd n·7} ~ . - ,,'" " monop.'mll/n , monOJlurln Figure 3c-f: High temperature gas chromatogram of bone scraper 400347 (e) and GC/MS chromatograms of soapstone lamp SL3 (d), bola 400399 (e) and wooden dish 342583 (f). 15 Solazzo and Erhardt Marine Mammal Oil and Cooking Practices in the Arctic ,·.G · . ___ .. __. ______._. _.. - -- ... -.- - _. '1 • Clay samples '" • Stone samples (I Wooden sample , , Bone scraper Bola • '., .,L------c------c~--c_-- • M _ • • ., M __• • -- ____., --___ ------J_ _ D/a c/ds % tOtll' ' II tty IIcids Figure 4: MonounsallJrated fatt y acids plotted versus dicarboxylic fatty acid s for artifacls from coastal Al aska . The stone bola 400399 from I'oint Barro w was covered most abundant, although C16:0 is the main free fatty with a thick layer of decom posed fat, low in palmitoleie ac id. Scrapcrs were used to remove fal from intestines and oleic acid, bUI very high in diacids. This is and skillS fro m scals. caribous or small lalld mammals. remarkable as the object was probably nOI exposed 10 The sample from wooden dish 342583 from northern heat, but used 10 kill scals. The presence of diacids could Al aska had a very high amount or monounsaturated fatty be due to biodegradation by micro-organisms of the acids and a quite high PIS rat io of 7.6. This sample was fresh re mains before the object was di scarded. The coll ected in 1929 whcn it was described as a 'flat sample from bone seraper 400347 from Point Barrow wooden dish used beneath stone lam p to catch drippings. was similar to the bola. hi gh in diacids (about 40%) and fou nd in place in an abandoned house'. The blubber was low in C16:1 an d C18:1. [t was also low in C16:0 and still fresh, which may explain th e high PIS ratio (ty pi cal C I8:0. On the chromatogram (Figure 3c). thc high of fresh bl ubber). concentrati on of MAGs is st ri king. MAG ·C I8:0 is the 353917 353961 354380-1 U2 U3 E I E I E I E I E I MAGs 0.670 0.090 8.348 1.843 2.556 4.309 1.2 19 -- 4.786 5.785 Monounsaturated fatty acids 30.964 21 .768 28.863 15.262 28.365 26.59 29.739 24.999 34 .268 24 .167 Diaelds 11.997 22.140 13.408 31.813 14.908 24 .167 17.051 29.151 14 .537 24.466 PIS ratio 3.268 4.042 3.154 1.223 3.280 2.885 3.748 3.898 2.671 1.828 Table 4: Comparison between samples taken from the exterior (E) and from the interior (I) of the sherd. MAGs are monoacylglycerides; diacids are dicarboxylic fally acids: PIS ra tio '" CI6:OICI8:0. 16 Theory and Practice of Archaeological Residue AnalysIs Discussion extreme cold of Alaska and northem Canada cvidently The archacological residues recovcred in thc coastal provides an ideal environment for the biochemical study arctic regions proved to have been remarkably wel1 of thcir former contents. preserved, most likely due to a particularly favorable environment. To summarize, our samples were References characterized by the presence of high concentrations Ackerman, R.E. (l961). Archae%gica/lnvestigations monounsaturated fally acids and diacids, a PIS ration of illto the Prehistory of Sf Lawrence Island. Alaska. about 3 and the presence of MAGs as wel1 as phytanic Univcrsity of Pcnnsylvania (PhD disscrtation). acid. Archaeological residues showed important Ackman, R.G. (1968). Examination of Isoprenoid Fatty similarities with the fat of marine mammals. Most Acids as Distinguishing Characteristics of Specific potsherds did not retain a recognizablc shape that would Marine Oils with Particular Reference to Whale Oils. enable to recognize them as fragments of a lamp or a Comparative Biochemistry and Physiology 24: 549-565. cooking pot. Lamps are likely to have contained marine Ackman, R.G. (1989) Marine Biogenic Lipids. Fats. mammal fat exclusively; cooking pots may oceasional1y and Oils. Volume II. Boca Raton, CRC Press Inc: 210- have been used to prepare land mammal meat, for 261. example caribou. It was not possible to test samplcs Badten, L.W., V. Kancshiro, M. Oovi and S.A. from such species, but if land mammals wcre used, Jacobson (cd.) (1987). L. Badtcn, Dictionary' of/he St. palmitic, stearic and oleic acids would be more abundant Lawrence Island/Siberiall Yupik Eskimo Language. (Malainey et al. 1999 a; b). Fairbanks, Alaska Native Language Center. Collins, H.B. Jr. (1932). Prehistoric Eskimo Culture on In the Northern Slope of Alaska, caribou could be St. Lawrence Island. Geographical Review 22(1): 107- encountered during its migration. It was also bartered for 119. sea mammal oil with thc land Eskimos. Two samples Collins, H.B. Jr. (1937). Archeology of Sf Lawrence from clay vessels from Point Barrow had about twice the Island, Alaska. Smithsonian Miscellaneolls Collectiolls average percentage of C18:0 (7%): SL6 with 13.57% Volume 96(1). Washington DC, Smithsonian Institution. and 400932 with 14.87%. In SL6 myristic and palmitic Colombini, M.P., F. Modugno, R. Fuoco and A. acids were also much more abundant than in any other Tognazzi (2002) A GC/MS Study on thc Detcrioration archaeological sample. In these two samplcs, terrestrial of Lipidic Paint Binders. Microchemica/Jourllal73, 1-2: mammal meat could have been mixed with sea mammal 175- 185. fat. Indeed, long-chain monounsaturated fatty acids were Colombi"i, M.P., G. Giachi, F. Modugno and E. morc abundant in thcse samples compared to the other Ribechini (2005). Charactcrisation of Organic Residues artifacts tested. in Pollery Vessels of the Roman Age from Antinoe (Egypt). Microchemical Journal 79, 1-2: 83-90. Many factors influcnce the biochemical modifications of Copley M. (2004). Organic Residue Evidencc for the foodstuffs. Were they cooked, fried or stored? How and Proccssing of Marine Animal Products in Pottery where were they discarded? 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