KARP SEAL (Phoca groaalandlca) CANmB DBN'l'Dm INCREMBN'1'AL AHNUL:I AS IND:ICATORS OF AGB AND/ORSEASON OF DBATH
By
George Hiseler
A Thesis submitted to the Seboolof Graduate Studies inpartial fulfilment of the requirements for
the degree of Kaster of Arts
Department of Anthropology Memorial University of Newfoundland
June, 1997
St. John' s Newfoundland
Acknowledgements
I would like to thank the employees of the Department of Fisheriesand Oceans who enabled this study to be conducted.
Gary Stenson permitted access to the DFO collection of harp seal canines and provided advice and sources on harp seals.
Training in aging by dentine annuli was provided by Wayne Penny and the sections were photographed with the assistance of Gord King. Pierre Pepin conducted th e computor ima g e enhancement and density image test on a canine section.
Foster Thronhill, Lapidary shop. Geology Department, Memorial University prepared the archaeological thin sections. The Archaeology Unit faculty . Memorial University, provided advice and direction during the proposal stage of this re s e a r c h. Special thanks goes to my supervisor, Dr. M.A.P. Renouf, who accepted the project and provided the archaeological material to analyze. Her advice and patience was greatly appreciated. Any omissions or errors are th e responsiblityof the researcher.
TABLEOF COHTEHTS
Acknowledgement s .. .... ... ... . .•... . . . ... . . . i
Listof Tables av
Lis t of Figures v
Cha pter 1 Int roduction l
Aging Based onDen tine/Ce me nt umTe chnique "
Archaeo l og ica l Applicat.ionDent.ine /Cement.umTechnique 7
Hypo t.h e sesandConunent.s . .. 9
Hypo t.hesis1 ..9
Hypot.h e s i s 2 .10
Bac k gro un d Informat.iononPort.au Choix Sit.es 11 Phillip' sGa rdenDors e t.Palaeo e s k imo Sit.e 12 Phil l ip's Garden East. Groswat.er Palaeoes kimo 15
Cont.ent.of Chapt.e rs 17
Cha pt. e r 2 Toot.hDen ti n e 18
Definitions .. . ... . . ... ... . . . ...•... .... . ..1S
Dent i ne 21
Physical Propert i es andChemic alCOmposit.ion 21 Structur e .. ... ... . . . . .... . • . .. . . .. . . . ... .... . . .22 Primary Den t. i n e ... . . ...•. . . ... . .... .. .... ... ... .23
SecondaryDe n ti n e 23
Incre menta l Lin e s 24
Int erglobula r Dent.i ne . 25
The Granu l a r Layer ... ... . . ... . 25
Age andFunct.ional Chang es . 25
Development. . 26
Causes for the Annul i Format.ion 26
Preservat ion ... ... . 28
Harp Seal De n t.i n e . 29
Ch apt.e r 3Modern Speci mens .. . 32
Ce ment.umor Dent.ine . 32
Longicud i n al Sectionsve r s usCross-s e ct.ion s .•.. . .. .. . . . 34
Tooc h Preference 35
Te c hn i qu e s for preparing Too t h Seccions 38
Decalcifying Teeth 38
Res inEmbe d ding .•.... .... . ..•... . . .. . . ... . .. . . .. 40
ffi~~t~:~~~~~~~~~i~~: : :: : : : :: :: : : : : : : : : :: : : : : : :: : : ::: :H
Grindi n g Sect.ions 43
St a i n ing . . . ... . . . ... . ... .. . 45
Methods to ViewTe et.h Sect.ion s 46
Accu ra te Absolut e Age Resu l t s 49
Conclusions 54
HarpSe a l CanineSect ion s 55
Prepara t io n Me t hod 55
Selec tionof Sec t io ns ... . . .. .. ... .. ...•. . ... ... ..55
ExaminationMet h od 56
Comments 59
11
Chapter 4 Archaeologi cal Application 60
Historical Summary 60
Detailed Techniques for PreparingToothSecti ons 68
ViewingTe c hn i qu e s 72
Mode rnRefge ren ce sa mples 73
Season of Death/AgingProblems 77
Port au Choi xSpecimens 81
Port au Choix Si tes 81
Arc hae o logical Proble m 81
Arc hae ological Samp le 82
Pr epa r ati on Met hod 83
Chapter 5 Harp Seals 84
General Informat ion 84
Aging Methods for HarpSe a l s . 88
Ne ona t a l Line . 90
Annual Nature of GLG's 90
Fa ct or s in Fo rma tio n of IGL's 93
Aging Based on Can i n es 93
Accura cy of Age Estimati on 94
Huntin g Met hodsfor Harp Seals 95
COlRllents 97
Chapter6Resul ts . . .... .. ... . . .... . ... .... . . ..• ... ...98
ModernTeethEstimates 98
ModernSeason of DeathEstimate s . 108
Implo c a t i o n s for Archaeologi cal Specime n s 114 Po r t au Choix Arc h aeologicalCanines 114
Season or Ti me of Death 127
Chap t e r 7Age Compos i t i on 130
Death Popu l a tion 134
MNI Requir ed 13 5
Dis crete Deposition... ... .•... .. .. ... . . .13 6
MNI Compa r i son s 13 9'
Taph onomy 140
Cull ing of Animals 142
Treatmentof Ca r c a sses/Bo n e s byMan .•• •• ...• • ••••. •. ..14 4
Cultural Practices . .145
Port au ChoixHarp Seal Age Compo si tion 146
Ch a p te r 8Co nc l u sion s 150
ModernHarpSea l Canine Secti ons 150
Aging 150
Seasonof DeathEst imat i ons 151
Archae o l ogical Harp Seal canin e Secti o ns 15 5
Aging 155
Port au Choix Ha rpsea l AgeCompositi o n 159
Seas on of Deat h Estimations 16 1
Seas on ofDea t h/Agi n g Problems. . ... .. ... .... . 162
Future Research ...163
References Cited 164
ii i
LI:STOFTABL BS
Table2.0.... •. . ...•. ... . . .. .• •..• .. . .. . . .. .21 Organ i c Compo nen t s of Dentinebyt Weight
Table 2.1 21
Inorganic Components of Dentinebyt Weight
Tabl e 3.0 36-37
Preferred TeethforSectioning
Tab l e3.]. 42
Saws used to Se c t ion Teeth
Table3.2 46
Tooth Se ctionSt a ins
Table 6.0 100
Canine SectionsAge 0 YearsOl d
Ta b l e 6.1 100
Canine SectionsAge 1 YearsOld
Tab l e6.2 101
Ca nine secercne Age 2 YearsOld
Table 6.3.. .. ... .1 02
Ca n i neseccrcneAg e 3 Years Old
Table 6. 4 103
Ca nineSectionsAg e 4Yearsold
Table6.5... ... .. ... . • • •.. . .. ... . . .••••. . .. ... . . . .. .104 CaninesecetcneAge 5 YearsOld
Tab l e 6.6 105
Canine Secc.i o nsAge 6 YearsOl d
Table6.7 106
Canine Se c t ions Ag e 7Ye a r sOl d
Table 6.8 106
Can i ne Sections Age8 Ye a r s Old
Table 6.9... .... . .•.... . . ... .... . . .. . .10 7 canineSections Age 9Year s Old
Table6.10 107
Canin e sec ercne Age10YearsOl d
Table6.11 108
Can i n e Sec t i ons Age 11+Yearsold
Tab l e 6.12 117 - 1 :1. 9
Caninesfrom Por t au Cho ix
Table 6.13... ...•... . ... ... ... . ... . .119- 1 2 1 Thin SectionAge Estimates
Table 6.14.. ... . ... .... . . .... . . ...122-1 24 Solid SectionAge Estimates
Table 6.15 125- 1 2 7
Actual Age Estimates Framall Data
Table6.16 128
La s t Annuli
Table 7. 0 . . 14 6
Ag e MNI for Phil l ip's Garde n Sample
Table7.1... .. ... . . .. . . ... . .. ... .... . 14 7 Age MNI forPhillip's Ga rdenEastSa mp l e
Table7.2 14 7
Numbe r of MNIs perMaturit y Groups iv
L:IST OP P:IGlJRES
Fi gu r e 1.0... ... ... . ... . . .. .16 Locationof Port au Choix
Fi gure 2.0 ... . ..20
Basic Too thComponents
Fi gu r e 2.1 . 31
Diagrammati cCrossSection of a Harp Seal Can ine Se ction
Figure 5.0 . 85
Pop ulat i on Loc a tions
Figur e 5.1 . 87
Migration Routes
CHAPTER 1 INTRODUCTION
This research project addresses the use of Northwest Atlant ic harp seal canine dentine incremental structures to determineage and/ o r seasonof death. Age determinat i onwill indicate the age compositionof theharvestedpopulation . Th e season of death (h a rve st time) is employed to derive an estimationof siteseasonality.
Determiningthe seasonof site occupation is a pr i ma ry objectivefo r most archaeologists. Season of siteoc c u p at ion or human occu p at i on period is also referred to as site seasonal i ty. Data on site seasonality provides valuable information concerning a culture's subsist ence / settlement pattern. The seasonaland/ oryearly subsistence system(s) is interrelated to th e entire cult ura l system and direct ly influences settlement patterns.
The Dorset Palaeoeskimo and Groswater Palaeoeskimo oc c u p a t i o n s at Port au Ch o i x, Newfoundland, are si tes wi t h unc e r t a in site seasonalities. The recovered fa un a l remai ns and excavatedhouse featuresprovide in d i c at i o n s of multiple seasonsto year ro undoccupation (Re n o u f 1987, 199 3, 1994 a, 19 94 b). The late winter to spring time period is firmly established ba s e d on the recovered faunal remains. This material is dominated by harp se a l s inclu d i n g some fetal, newborn and juvenile (young of the year) bones.
The migratoryharp seals are known to whelp on ic eof f
Port au Choix in late February to early March and remain in the area until at least May. However, harp seals alsomigrate past Port au Choix in late December to January ahead of the advancing ice. They could be taken in the open water by net or harpooned from a watercraft during this period. Thus, a middle winter occupation period could be assumed if any of the harp seal material is from Decemberor January.
The only potential method available to dist inguish between the southward migration (De c e mbe r/ J a nu a ry) and northward migration (late February toMayl involves dentine incremental annuli. This direct seasonality (Monks 1981)and aging (Bowen et;al. 1983, Fisher 1954)method will constitute my research project. Dentine and cementum are analyzed by techniques based on the fact that a regular yearly detectable annul i pattern is formed. Interpretation of this pattern can indicate age and/or e ime of deathfor the individualspecimen.
Age is determined by counting t.he yearly annuli and time of death is suggested by the latest annuli's stage of development _
All age composition data are based on the assumption chat the faunal material recovered and analyzedrepresents the encire original death population or a representativeportion of all age groups utilized. However, there are a number of problems with this assumpcion and wich conscrueting age composition profiles based solely on teeth. Firstly, determining an accurate population size must be based on more
than one body el e me n t (i.e. teet h). Tha t is, popula t i on nu mbe r/MNI (mini mumnu mberof ind ividuals)bas e donte e th must becomparedto the MNIderived fromother bodyelements (i .e. humerus,femur,sc apu la,etc.) re c o v eredinor der tode t ermin e how accurately the teeth MNI repr e sent s the de ath population co nt ai ned in the unit/feature.
Secon dly, all teet h sect i o ned ar e unl ikelyto produce readable sections (Spi ess 1990:37) thus the comp l e te age compo s i t i o n of th e re co veredfaunal materi alwi l l beunknown.
Theproport ionof unreadable specimens to totalspecimenswi l l direct ly affec t the data's accu r a c y. For exa mple, a few no nagedspec imens in a small sampleco uld greatly alterthe ap p a r ent age composi tionprofile.
Ot he r potential proble m areas are a smal l popu lation size ; how to quantify and identify loose te eth to specie s ; whetherthe deposit repre sentsa si n gledi screte,seas o nal, or mu lti-ye a r deposit i on; and the assumpt i on that butche ryand culling patterns ar e unifo rm for a cu ltural group or si ngle sp ec ieswi thin a seas o nal or yearly depos it.
Like wise, there are ca vea ts to det e rmi n ing si te seaso na l i ty. For example, the conn e c tion between the spec i men's tim e of deathand some behavi oralac tivit yof the cu ltural group must be de monstrated (T ho ma s 1979:2 61). A direct correlationbetweensiteseasonal ityand a specimen's time of death canno t be assumed where stored (Sa v e l le 1987:72), traded (Da vis 1987: 75), or transported IMo nks
1981:226) reeourcea ar@utilized.
Es t i ma t ing sit@ seasonality wil l depend on howprec ise (da y, we ek, month, etc. ) a seasonal indicator den ti ne increme nt al structures ar e . Mo nk s (198 1:17 8 ) note s th at eeeeceartev or timeof year can becon si d e r e d asan absolute calendrical date, s@quential da t e (es t i matio n of spring, summer, fall orwi n ter se a son)or Jochim's (19 76:4 5) proposed economi c season. Theeconomi cseason is aperi od,measuredin cale n d e r mo nt h s,wh e n acl e a rly not iceableand regular group of subsistenceactivities takes place.
AgingBasadon Dentine/CementumTechnique
Scheffer (19 50) and Laws (19 5 2)developedte c hn i ques for agingmarinemanmalsus ingin c r e ment al growth laye r s in teeth . Wildlifebi o l ogistshave co nt inued toutili ze thesetec hniques invo l v i ngden ti ne/c e ment u m annuli (in cre men t a l growthla ye rsI toageterrestrial an dmar ine mammals fo r de c a d es (F l e t eme y e r 1978; Goodwinand Bal l ard19 85 ; Mit c h e ll 1963; Ransom 196 6). The techniques are based onthe fact that a regular yearly detectable dentine/cementum layer pattern is formed. This concept is simi lar to that of dendroc hro nology (t r e e ring dating)whic hisbased onthe regular yearlyconcentric growth ring patt ernoftree s.
Researchwi th knownage mammal spec i mens has shownthat the layers are pr od u c e d annual lyand that the techniquecan p s-cv Lde accurate absolute age results (Bowe n etal . 1983;
Doubled ayan dBowen 1980; EricksonandSeliger1969; Li nha rt and Knowlton 19 6 7; Low and Cowa n 1963; Scheffer 1950 1 . Abs olute ageac c ordi n g toMor ri s {19 72: 711 -Ls an animal' sage exp r e s s e d inprecisemeas urementsof time, usually months or ye a rs.- Obta ining accura t e ag e es timates is dependent on det e rmi n i n g discr e t e in cremen t a l annuli {Gas awa y ee aL, 197 8 : 56 11. Howe ve r , Goodwin andBal l ard (19 85:315)notedthat ac c u r a c y of age determina tion varied wi t h the rea d er's exp erie n c e ininte rp r e t i n g inc rementalannuli.
Cemen t u m is pr e f e r r e d ov e r dentine for aging mammals becauseinolder marrunalsthe cement umreadings are considered more rel iable. Dentineisdepo s i t ed in t e rnal l yunt.i l th e pulp cavit yis filledbu t the ext.ernallydepositedcement.umis not limitedby sp a ce bl! i n g producedunt.il t.heanima l's deat.h. As thepulpcavit yis filled wi th dentine the laye rsbecomemore co mp ressedan d diff i cu l t todi s t i n gu i s h. Thece me n t umlayers are not compressed and general lyea s y todi s t inguis h. Bu t , harp seals on l ypr odu c e a thin cementum lay e r andthe cement.u m growth layer groups are not re l iable for age estimat i ng becauseth e y are usually indi s tinct (Bowe n etai. 19 8 3: 1 4 3 21 . Thereforeresearchersexaminetheden t i neannuliwhen studyi ng harpseals.
Anumber of to o th section prepar at:ion technique s are avai lab l e to fa c i l i ta t e and enhance the re ad i ng of de nt i n e/c ementum annu l i (Se e Chapt e r 3). The basic techniques for preparing mammalian te e th are: il decalc ify i n g teeth
(u s u a l l y involves formic acid or a formi c acid/fo rmalin solut.ionl; iii razo r sectioning; iii ) microt.ome sectioning including both the standa r d paraffin technique and t.he fr ee z ing techni que; iv) st a ining wh i c h most commonly is he mat. oxyl i n; vl ground section s viewed with cransmitted lig ht; and vi) ground seccLons viewed wi th reflected li ght (Fa nc y 1980).
These tooth pr eparat i on t.echniques permi.c'ted dentine/cemen tumannuliaging to receive wi d e acceptanceand to be applied cc a range of terrest.r ialmammals. The mammals studied in c l u de th e badger (Crowe and Strick land 1975l.
vampirebat (Li nha rt 1973 ). blackbear (S t o n e be rg andJo nk e l
196 6;Wil l ey 1974) . grizzly bear(Cr aig h e adet: al. 1970;Mundy and Fuller 1964). bison (No v a k ows k i 1965) . bobcat (Cr owe 1972). ca r i bou(McEwa n 196 3 ;Mil l er 1974). coyo t e (Li nha r tand Know l t on 1967; Ne l l i s ecal . 1978), dee r (Lo c k a rd 1972; Low and Cowan1963) .elk (Ke i s s 1969),redfox (Al len 1974 ;Harris 1978). moos e {Gasa wa y e eal. 197B;Sergeant and Pimlott 1959;
Wolf e 1969} . otter (S t e p h e n s o n 197 7). North American sheep (Tu rner 19 77). andsqu i rre l (Adams and Watk i Il.S1967) .
Researchers have applie d the in c r e me n t a l gro~h la y e r techn i que toa va riet y of ma rine mammal s (wha l e s and se als) (Sc he ff er and Myri ck 19BO) . Klevezal andKleinenbe rg (196 9 ) list twenty-one Pinnipedia speci e s known to have annual dent ine or ce me n tumlayers. Sea ls aged by this technique include fur (Anas 1970; Scheffer and Pe t e rson 1967) . grey
(He wer19 6 0 ),harbour(Mansfie ld and Fisher 1960),harp (Bowen et: al. 1983), Hawaiianmonk (Ke nyon and Fiscus 19631 , and ringed(Smith1973) . The Cana dianDepartme ntof Fisheriesand OCeansco n t i nu e s to age bea rded, grey, ha rbour, harp, hoode d and ringedsea lsbythe dentine/cementum ann u li te c hn i qu e.
Although bi ol og i s t s are concerned wi t h aging the spe c i mens ,most report scon t a insome da t aonthese a s on (time) of dentine/ce mentumlayer form ation. Usually, th e y describe the la s t annuli formed and th e ti me (day. month, etc.) of death (Cr a i g h ead ee al. 1970 :35 3 ; Erickson and Seliger 19 6 9:387 ). Se asonality is then prese nted ingross termsof between winter and summer or win te r/s p rin g and su mmer/f a ll
{Ada ms and Watkins 196 7:83 7 : Mitchell1963: 35 1l.
Archaeologica1 App1ication of Dent i n e /Cementum Technique
Th e disciplineof archaeo logyhas ad aptedthes eme t h o d s and techniquesto estimateageat death and/or se a s o nof de ath of archae o logicalfa un a l remains (Cox and Spiess1980 ;Gordon 1982. 1988; Gustafso n 19 6 8; Kay 1974; Sav ell e and Beatt ie 19 8 3 ; Saxon and Hi gh a m1969; Spiess1976, 1978, 1979, 19 9 0;
Wi lson 1978). Bourque et al. f1 9 7 8 : 5 3 0 ) suggest three advantagesfor archaeologis t s in us ing mammal ianteeth as a seas o n a l indicator. The s e advan tag e s of mammal i an teeth are du rabi lity , the fact that they are usu ally id e nt if iable to genusor species, and thattheycvez-ecme the need for la r g e
sta t i st i c al ly signif ican t sample {Bou rque et: al. do not expl a inwhy this is the ea s el. Bu t, na t all manmalian te eth recovered will produce readable thin secti o n s beca u s e of al t e ration (from fireetc . ),poor preserva tionordestruction duri n g thin sectionpreparat ion .
Comp ared tobi ologi st s , arc hae ologistshave studi e d only a limi ted nu mbe r of terrestrial and ma r i n e mammal sp e cie s us i ng thede n t ine/c eme nt umannuli techn i qu e. These inc l ud e blac k bear (Bo u rque ee a1. 197 8 ) ; bison, Bison antiquus (Bo urqu eet:al. 1978; Christe n sen19711 ;car i bou(Gordon1982; Save lle 1987; Spiess 197 91; wh it e-t ailed de e r (Kay 1974: Spiess 19901 ;muskoxen {Save l le and Beattie 19831; greyseal (Bl ac k19 8 9); harpseal (Spi e s s 19 7 8) ;ring e d se a l (Mc Cul lou gh 19 8 9 ; Savel Le 19 8 7; Spies s 1978: Whitridge 19901; andsheep
(Sa xonand Higham 1969).
A mode rn ba seline reference samp l e is required for in te rpretingthe archaeo logical specimen' s ag e and/or se a son of death. That is, t.h e t.echnique of dete rmini ng age and season of death must be establ i s h e d for modern spe ci men s befo r e archa eological specimens can be interpreted. Modern specime n s can provide verifiable data not availabl e for archa e ological specimens. Using specim ens of knownage ca n verify th e techni que fo r aging bas ed on increme n t al annul i. Also, the modern refe r e n c e sample (of known timeof deat h) pro v i de s ve r i f i ab l e data onth e season (t ime of de a t h) whe n thedentin e/ceme ntum annul i ar e formed.
Following the principle of uniformitarianism, the researchers assume a direct corre l a tion or no signif icant dif ference between modern spec imens and archaeo log i ca l sp ecimen sin increment al annul iformat i o n. This impliesthat modern specimen s deve lop e d unde r th e same con ditions and season a l i tyfactors as the archaeo logic a l specime n s.
Hypotheses and Comments
The research is designed to test th e fol l owing hypotheses:
Hypothes i s 1. Ac cu ra te age and/ or se a son of death estima t e s can be determined from canine dent ine inc r e me ntal growt h la y e rs for mode rnha rp seal s (Phoc a groen1 andica).
This is a eeecanre hypothesis as age re s utcs be verified for eb e spe c i mens of knownage. Also, seas o n of de a th eee imaeee canbeverified becausethe time (d ay and/or roon tihl of death is known foral l che studied sp e cimens .
Agi ng ha rp seal s usingdentine annul i is an establish ed and proven tec hniqu e (Bowe n er a1. 19B3 ; Fis h e r 1954) but.
determining season of death has nev e r been adequately addressed. The applicationto archaeol ogical specimenswil l be testedon c e th e dentine techn i que for agingan destimati ng season of death estimates has been estab l i s h e d on modern cani n e s.
Hypothesis2. Accurateage and/or season of death estimations can be determined from canine dentine incremental growth layers of harp seal (Ph o c a groenlandica) archaeological specimens based on a modern baseline sample.
The hypothesis is untestable as there are no known age or time of death archaeological specimens to verify t.he results.
In theory archaeological specimens whose age and time of death have been established by ot.her means (a g i n g pattern of elements formation, seasonal cycles of modern species) could be used for verification thus making t.he hypothesis t.est.able.
Also, th e hypothesis is based on t.he assumption t.hat.
regardless of time difference modern reference dat.a ca n be applied t.o archaeological material. This implies t.hat. no variation in seasonal rounds or change in migration pattern for harp sealshas occurred through time. The assumption is addressed by reviewing changes in modern seasonalit.y movements and the possiblefactors th a t influence such changes.
Anot.her assumpt.ion is t.hat. harp seal season of death in d i c a t. e s t.he season the Port. au Choixsites were occupied and is not. a reflect.ion of ot.her factors (s t o r a g e , curat.ed mat.erial, etc.)_ This assumption is based on the fact t.hat harp seals are present.lyand were hist.orically hunted off Port au Choix. It. is highly imp r o b abl e that harp seal carcasses and remains were brought to a sit.ewh e r e they were readily
10
available. But, harp seal season of death mayreflect only a portion of th e time the site was occupied.
Aging and/or seasonof deathfor archaeological harp seal specimens is not a well documentedprocedure. Spiess (1 9 7 8 ) has analyzed a few canines, from Labrador sites, based on a very smal l reference samp l e. A modern baseline sample of knowntime of death is required to provideprecision in the interpretation of archaeological specimens <Spiess 1990: 30). I believe this baseline sample must cover the entire period of development being analyzed and include enough samples to account for individual and yearly variations.
If season of death estimatesar epossible based onmodern specimens then interpretations of archaeological site seasonality can be made. Besides separatingthe two migration periods. i t may be possible to divide up the late winterto spring period. A division of this period wouldhighlight any changesin cullingpatterns or hunting strategies during the harp seal harvest.
Background Informa tion on Port au Choix Sites
Prehistoric artifacts and remains have been recorded for the Port au Choix (F i gur e s 1.0) area sinceth e turn of this century. Howley (1915:328) reports that ivory and bone artifactsalong with humanremains were recovered in theearly 1900s. The first concerted excavations were conducted in
11
1949, 1950and19 61-62 by ElmerHarpJr . (1 9 64) main l y in an areakn own as Ph i llip'sGarden. The Dor s e t Pal a eoeskimo site con s i s ted of numero us ho u s e depressions that possibly represen t two typesof ho u s i n g. Harpbel i e v e s tha t there are bothwi nte r and summer houses onthe si te. The ex c ava tions also producedmassivequantitiesof bone that Harp identified asmainlyha rpseal.
In19 6 7 Tuck (1 976) excavateda MaritimeArchaic Indian buria l ground con t a ini ng grave goods and ei g h ty· nine in divid u a lsin fif ty-fiveburials. Pa rks canadaac quiredt.he area in 1984 and con t r ac t e d Dr. M.A.P. Renouf, Archaeol ogy Unit, Me moria l Uni v e rs i ty. to co n d uct an archaeology su rvey.
Thesurvey would help infu t u r e park dav e lopment an d des ignate areas for potentia l research.
Renouf's site excavations have identifiedboth Dorset Palaeoeskimoand GroswaterPalaeoeskimo occupations . Nu me r ou s art ifacts and large quantities of faunal remains ha v e been rec overe d. The vast amount of the faunal mat e ri a l is seal tha t is domi natedby harp seal. Harp seal can ines recov e r ed byRenouf. at Phill ip ' s Ga rden and Phill i p'sGa rden East ,are the arc ha e ologi cal materialbasisforthis researc h proj ect.
Phi l l ip'. Garden ne eeee Palae o e skimoSite
Phill ip' s Gar d e n isatwohectaresi tecomprisedofthre e rai s e d shorelines. Numerous smallrectangular. ova l and round house depressions are loca ted on the upper two raised
12
shoreli nes. This site was occupied for at le a s t 400 years between 1900-1500 ye a rs ago but may have been occu pie d for ne a r l y1000 years.
Th eex c a v a t e d house depressionsin dic a t e di fferent house layouts which Renouf (1 9 94a) interprets as representing seasonal di ffe r e nc e s. These include winter/spring, spring/summer or fall/early wi n t er st ruc tur e s and a summer wi n db r e a k. However, al l threehouse typescould ref lect the changing con d i t i o n s withinthe February to June (la t e winter, spring, ea rl y sUlmIer) period th a t se a l s are ava ilable.
The si te co ntains extensive middendeposi ts with well preservedbon e because of the limestone bedrock. Se a l bone dominates the faunal remains with a pr edo mi n a n c eof harpseal.
The seal materialin c l u d e s varying amounts of fetal,newborn an dju v e n i l e remainsin the featu r e s. Feature 2 (a c t u a l l y 12 subfeatures) contained small amountsof ne wborn and juvenile seal, newbo rn material was identified in Midden F'eatures 49 and 32, and House Feature1 hadsome juvenile re ma ins.
Th is se al mater ial indi c a tes a la t e winter to spring occup a tio n tocoincidewith th e whelpingandmoul ting periods and the June/Julyper iod whenonl y juveniles are available. Duringthewh e l p i ng and moulting periods, harp sealswould be readily available on the ice along the Port au Choix coast.
The other faunal remains recovered sup po rt this time period CHise l e r 1990al. However,thesespeciesare also availableat other ti mes during the year. Renouf (1 9 94 a : 11) hi g h l igh t s
13
some of these alte rnative time pe riods by stating that
·caribouare close st to Ph ill ip' Ga rde nin thesumme r. Late Bummer is su gge sted by the pr e sen c e ofthe now- ext i nctgreat auk.·
The great auk is the onl y species identifi ed fo r Phi l l ip'sGard e n that is notavailabl e durin gthe late wi nte r to spring peri od accor di ngtoRenou f (1994a). Re nou f reports that Mont evecc h i (Re nou f 1994a:I I I state s a late summer {Ju ly/Au gus tl migrat io n isposs i blebut ic ein theStrait s of Bell e Is lewou l d havepre v e n t e d a spri ngmigration . However, the harp seals mi gra t e th rough the Stra its of Belle Isle followingthe retreating ice and reach Por t au Choi x in late Februa ry. It isals o known that some Gul f he r d seals wh e l p off Labrador when ice cond ition s are poor inth e Gulf (Bowen 1985). Thisindicate s tha t th e Strai t s are notalways blocked by ice andthe refo re aspr ing migra tionof greatauk wo ul d be possi bl e.
Theharp se al nort hwa r d migrac i o n period (la t ewi n t er to ea r l y summe r) can ac c o unt for faunal remains and house struct u r eslo cat ed ac Ph i l l ip' Gard en. Howeve r,an ext e n d ed or oth er seasons of occupa tion are pos sible fo r Phillip's Gard e n ba sed on the same data. The an al ysi s of harp seal de nti n eannu li ma y determine i f th e occup a c ion peri o d can be ext en d e d into midd le winter (Dec e mber/Janu ary).
14
Phill ip' .Gard ens •• t Gr o . - t . r P. l••o••kimo Sit . Phi llip's Garden East borders the Dorset Pal aeoeskimo Phi l l ip's Gard e n sit e cov e r i n g approxi mate ly 1500 square meters. The sitehas excellentbone preservationand contains at leasttwohousestruc tures wi t h sixpitfeature s . Mat e rial rec o vered to date in clud e s ov e r 270 0 li t h ic artifacts and 75.000 faunal rema ins. Thesitewasatleast occ up iedbetw e e n 276 0+/ -9 0B.P. to 1930+/-1 40 B. P. and ut il iz e d on a regu l ar seasonal basi s (Renou f 19 94 bJ .
The site reflec ts re pea t e d occup at ion s during the late win ter to springharpsea l hunt. Harpse a l dominates the seal mate rialrecoveredtha t is 90t of thesite' sfauna l remain s. The late win t e r periodis ind ic a t e d by the smal l amoun t of harp seal fe ta l material. The high numbe r of juveniles support the la te winte r/s pr ing periodbut cou ldalso in d i c a t e a May- July hunt wh entheyare the on l y agegroupava i lable.
Renouf (1 994b) report s a highamountof proce s s i ng tool s that indicatesa functionspe cificoc cu p ati o n. Thisfun c t i o n wou ld be th e harves t i n g an dpr oc e s si ngof th e migratin g harp seal. Phillip'sGarden Ea st would beseasonal lyre-occupied and thes e occupati onsmight have been va r i ab l e based on th e two diff e rent house structures. The harp se a l dentine developmentinthearchaeologicalspecimens may help tode fine the pa r ame ters of the occup at ionsea son.
15
Fiq ure 1.0 Port au choixArchaeologi ca l sites (aene ur1994b:168)
16
Content of Chapters
Chap ter 2 provides bac kg round information on the development. composition,and preservationof dentine. Als o, th e gene r alstructureof te e th and th e availabledata on harp sealdentine arereviewed. The methods toprepare and examine modern and archa e olo g i c a l too th sect ions are di s c u ssed in Ch apters 3 and 4, respectively. Incl ud edin the discus sion areth e te c hn iques utilized for this resea r chproject and the pro b l e ms encountered. Da t a on th e harp seal. inc l udi n g migrat i on routes and age group habits. ar e presented in Chapter 5. The seasonal ityand aging results on bot h the modern and archaeological sp e c i me n s is pre s entedin Chapter6. Cha pter 7con t a insa discussionof the potentialand probl ems in develop ing harpseal agecompositionprofilesbasedon the can i n e increme nt al agi ng te c hn ique. Also, the re su lts of arc h a e o l ogi cal spe c i me n s ag e dby thetechnique are pres e nted and analyse d.
re s e a r ch.
Chapter e co mpr i s es the conclus ions of the
17
CHAPTER 2 TOOTH DENTINE
A brie f descr i p t ionof thetooth ' s basic components {Figu r e 2.0 1 provides a frameworkfo r und e rs t a n dingde nti ne's struc ture and func t ion . The root(s). con tained inth e jaw, andthe crown arethe t.wo major sect ionsof a tooth. Ena me l covers the crown wh i le the root(sl is coated byce men t u m.
Under the su r fac e la y ers is den t i n e , th e toot h ' s main struc tu r e, whi chen capsula testhe pulp chambe r .
DBF:INIT:IONS
The defini t ionsare basedon thein t e rn a t i o nall y accepted mean ingsfor marine mammals (Pe r r i n and Myri ck1980: 48-5 0 ).
Cement um - al ways fo rms layersove r the rootbu t incert.ain species als o form s la yersover co ronal section. The cementum provide s for tooth at.tachment. Th is mesoderm a l originated ca lcifi e d tissue frequent l y includ e s osteocyt.es
lc e men t ocytes).
Crown - the di s t al tooth sectio n whi c h projec ts from the gingi v al surfac e andiscoveredbyen a mel inmost spec i es.
Dent ine- a mesodermaloriginatedtissue that is cellularand ca lci f i e d . With the exception of ziphiids the crownand root cons ist primarily of dentine. The crownde ntineis coatedby
"
ename l while therootdentine is covered byce mentum.
Enamel - an ectodermal ori gi nat ed mineralized secret i on coveringth e dentineexternally. Cementum may coverareasof the ena me l.
Growth layer group (GLG) - countable units of inc r e mental growth layergroupingsthat fo rm a repeating or semi-repeating pat t e rn. Eachunit will containone ormo re contras t change (i.e.dark tol ight , ridge to groove) .
Iner ement algrowthlayer. (I:GL) - la y ers running paral l el to th e formative surface that are discernibly di f f e r e n t from adj a cent la ye r s in hardtis s u e (d e n tin e, cementum, bon e) .
Neona tal line - an orthodentine growth la y er that divides prenatal de n t i ne from postnatal dentine . This divi sion probab l y results fro m early pos t - p ar tum nutritional di stu r ban c e s.
Pulpcavity- th e centraltooth chambercon t ain i ngco nnective, se nsory and nutrit ive tissues . Th e dentine de f ines the boundariesof the pulp cavity .
Enaml l !lloIbllanlia adamantlnO!
u-- - --
Ntonolal LintPunalal Denlinl
Orlhad,nlinl (sloIbs la nli a tburn, ol
Pall llOlalOlnl ine
PulpCavil ,
C,m,nlum hubstantiaa, 1I a)
' -"'--- RaolCanal
Fiqure 2.0 BASi cToothcompon e n ts (Perrinan d Myri ck1980:49)
20
DI!NTINB
Phys ical properties and Chemical Composition
COKPOlIENT
\ """GIlT
co l l a g e n 17.5-18.5
resist.antprotein 0.2
cit r a t.e 0.8 6 - 0.8 9
la c t at.e 0.1 5
lipid 0.0 4 4 - 0.3 6
chondroitinsulphate 0.2- 0.6
water 5
Table 2.0 Organi c COJlIpOnentsofDentineby11 we ight
COMPONENTS 11WB:IGHT
Ca 26-28
P 'a s PO/"and HPO/-J 12.2-13.2
p (a s pyrophosphat.e) 0.05
CO, (a s carbonate) 3.0- 3.5
Na 0.7
Mg 0.8-1.0
Cl D ••
K 0.02 -0.04
PAlt'1'S PER.MrLI.:ION
F 50 - 10 ,00 0
Pe 60-150
zn 200-700
Sr 100-600
Tab l e 2.1 :Inorganic COlllPonent.of Dent ine by , we ight or Par t s per Kil lion.
Unles s ot h e rwis e cited all the informa ti on conce rnin g dentine is fromAv ery (19 86) .
Dent i ne is softerand elast i c compa r ed to enamel but harde r tha nbon e. Thecompositionofdentine is 65\ino rgan i c mate ri al and 35\ organic matt er an d water. Co l lag enous fi bri ls (Col l a g e n of typ e II are the main component of the organic mate r ial . Ot h ercompo n e nts are glycosami n og l ycans, proteoglyca n s, phospho p ro t e ins, gl y c o saprote i n s , andpl a sma proteins {To rneck 19891. The inorganic material is hydroxyapatite with small quanti t ie s of phosphates, carbonates,andsul fa tes. Decalcifiedte e thproduce valuable histolog icalsect.ionsbecausethe dentine shape is preserved an d the organicconsti t uentsareretained. Ma t u r e dentin e's wei g h t andvolu me perc e ntages differfor ino r ganicmate rial, organi c materialand water . Respe c t i v elythepe rcenta g e s by weight are 70\, 20\, and lOt whi le for volume they are 45\ , 33\, an d 22\ (Torne c k 1989). The primary and second ary den tine are che mically dif f erent (Shi pman ee a1. 1985). Va r i a tions inmic ros c o p i c dentinestructures betweenmammals has beenob s e rved (Hills o n 1986),
Structure
A rand omframew ork of co l l a ge nfibresfo rms thede ntinal matrix. New dentine , called predentine, forms layers cir c umpulpal ly . Intertubular dentin e compri s e s th e major port i o n of denti n e betwe en
22
of peritubul a r dent ine.
Exceptadjacent to the pulp, peritubular dentineformstubules walls .
Primary Dent ine
Primary dentine is composed of mantleandcircu mp u l p al dentine. Mantle dentine is the outer part of primarydenti ne first formed in the crown. After the ma ntle dentine has form e d the remaining or g an ic matrix is formed by the odontoblasts. Ci r c u mp ulp a l dentine fo rm s the bulk of the tooth representing the dentine form ed prior to root co mp l e t i o n. Aslig h t l y higher mineral content isone possible difference betweencircumpulpaland mantledentine.
Secondary Denti n e
Secondary dentine is the dentine fo rm ed after roo t co mp l e t io n and unevenly deposited around th e pulp cavi ty ' s periphery (To rne c k 1989). There isco n t i n u ousde pos i t i o n of se c ondary dentine oc c urr i n g in th e pulp chamber througho u t l ife (Hill s o n 1986). The earliest dentine forms closest to the ou t e r tooth wall s whi le the la t e s t is next to th e pulp cavity (Klevezal andKleinenberg 196 9).
23
Incremental Lines
The incremental lines are fin e st ria tions in dentine whichoccur at right angle s to thedent inal tubules. Dentine incremental li n e s directly correspond to enamel and bone in c remen t a l li n e s. These lines mirror the recurrent daily rhythmic deposition of dent ine matrix and the quiescence period. in the dailyformativeprocess. Hil lson (19 86) reports that sha rpnessandspacing of increme ntal li ne s va ry wi t hin a toothandbetweenspecies. But, the sequenceof lines in any tooth of an indiv i du a l ca n be mat ched to that in d ividual's othe r teeth. Acc ord ing to Hills on this "imp li e s tha t the rhy t hm is undersys t e mi c cont rol." The dentineof deciduo us teethand firstpe rma n e nt molars is composedof pr enatal and postnatal dentine. The prena t al and postnatal dentine are separated by the neonata l line tha t reflects the abrupt env ironmental change at birth. The neonatal line might represent a zone of hypocalcification .
Some points tocon s i d e r about incrementallines ar e:
al Less distinct lines ar e best de t e c t e d with longitUdinal groundsectionsaccording to Torneck (1989).
b) Not al l mammals or teeth and bones of mammals form or prese rve incrementallines (Kleve zal 1980:89).
et In cre a s ed primary incremental laye r wi dt h resul t s in add i t ion a l accessory/second a ry increme n tal li ne s (Klevezal 1980(89).
dl Generally ma mmal s in climatic zones with no pronoun ced
2.
contrast between warm and cold ordryand humid seasons will form in d i s t i n c t and variable incremental layers {Klevezal 1980:92}.
Interglobular Dentine
Interglobular dentine is known as hypomineralization zones between the globules. These zones are formedwh e nsmall mineralized dentine globular areas fail to fuse in to a homogenous mass. The in t e rg l o b ular dentine forms in the crowns of teeth below the mantle. Deposition of the int e r g l o b u l ar dentine followsth e incremental pattern.
The Granular Layer
Named for its appearance, th i s granular appearing root dentine section abuts th e cementum. The granular layer's formationprobablyresultsfromthe coalescing and looping of dent inal tub u l e s' terminal sections.
Age and Functional Changes
The process of de n t i n og e n e sis and seco ndary dent ine production slows shortly after the teeth erupt. After eruption tooth damage from dental caries, abrasion or attri t i on is repaired by reparative dentine.
25
Development
Dentinogenesis is the origin and formation of dentine (Melf i 198 8 ) and is formed by ce l l s called odont oblasts . Apati te crys t a l l i t e scalc i f ytheor g a ni c matrix with dentinal tubule s of odo ntobl a st cyto p l a s mi c ex t e n sion s are produced dur ing dent i n ogenes is . The or g a ni c matri x is pr o d u c e d by od o n tob l a sts and mi neralizes (globula r or cal co s p h e ric calci f i cation) to fo rm dentine . Odontobl asts di f f e r e n tia t e d "fromthe ectomesenchymal ce l lsof thedental papi l la foll owin g an organizing influence emanatingfrom the cell s of de n t a l epithelium " tcaue 1989). Dentinogenesis beg i n s at th e cu s p tips with the form i n g and th e n calcif i cat i o n of th e col la g e n matrix. Daily inc r e me nts of pr e d ent ine are form e d andcal ci f i e dthe follo....in g day . Once the crown fo rm s and the te e t h erupt the de n t i n e produc tion decreases. A further decrease of denti ne pr o ducti o n is pos s i b l e afterro o t devel opment .
Causes for the Annuli Formation A ful l range of metaboli c andenv i r o n me ntal suggested for annuli form a t ionin mammals . Th e s e fact orsmay ca u s e th e format i o nofden t ineannul iin harp seals. Someof the s e ca u s e s are:
a) chia s s o n (1 9 5 7 )sug g e s t s dark de n t ine is formedin Alaskan fur seal during th e thre e month non-feedingland oc c u p a t ion period. A ....ider dentine bandrepresentsthe nine month sea
26
period. Va r iation s in annuli are in f l u e n c ed by nutr i t ion, pa r a s i t i s mand disease. Als o. males on land utilize their bui l t up fat deposits whi c h lacks ca lciumsa lts required to build ena melor dent i ne.
b) He wer (1960) sugges t s that early br oad annuli in grey seal s ar e depositedpriorto sexualmaturity. Semi-st a rva tion duringthe moultperiod is res p ons i bl e for these annuli being visible.
c) The visible interruptions in ce mentum and dentine depositionin Hawa iian Monk seals results fromfasting during th e moult period(Ke n y o n and Fiscus 1963).
d) Lowand Cowan (1 9 6 3 ) believe nutritionisa prime fac tor in visible annu l iproductionfor mule deer.
eJ Differences in seasonal nu t r i t ion and sunlight may influence seasonal cementum depos ition for barren ground caribou (McEwa n 1963).
f) Seasonal me tabolic disruptions (i . e. denning, etc.1 combi ne to produce the annuli in black bears (S t o n eberg and Jonkel 19661. Rausch (1 9 61:16) studied non-denning captive bears and foundno di s t i n c t layersof dentine.
g) Possibly enVironmentally str e ssful periods produce the similar annulations in No r t h Amer ican sheep tee thand horns (Tu rne r 19 77).
Anyof the above could be possiblecausesforth e annuli formation in harpseal s. Resea rchtodate has been unable to pro v i d e a precise correlation between a metabolic and or
27
en v i ronme n t a l eve nt and theannuli format i o n .
Preservation
Hi l l son (1 986 ) st.a t.e s t.hat. we l l preservedfos sildentine ap pea rs like fresh dentine . Bu t. fossil dent ine often displaysvaryingdegreesof alterat i o n suc has br i t t l e n ess,or softeningfromcollage n lo ss . Alt houg h collagenislimited in its suscep ti bi lityto bacteri a and fungi.slowto ch e mica lly di s i n tegrate . an d is ins oluble in wat er when heated , it.
ra pidlybre a k s do wn to formge latine . Thedentine tissue is co mpletely dest.royeddurin g the latephase decompos itionlos s of th e apatites (c a lciumph o spha t e s ). Va r ious archaeologic al contex ts, su c h as heatingcha ng e s fromfire, ca n prod u c e t.he alt e r e dopacityan ddentine stru c t ure that is visib l e in tooth sections. Shi pmaneea1. 1198 4Jexpe rimented wi th the ef fe c t s of hea t on she epand goatteeth. Increasedtemperatu r eswere found to progressively alt e r hydroxyapatit.e and collagen;
microsco pic structures; and create shrinkage due to wat e r loss.
Bi o c hemi cal andrad iograph i c researchon arc haeological dentine spe c i me n s bySeel e y and Lunt (19 80 ) sh owe d:
al Mine ralconte ntof th e tissue wa s unch a n g e d.
bl Col lagendegenerati o n cre ateda change in con s i s tency.
c) On l yth e fina l destruction stagesof bone and toothsh o we d min eral loss .
dJ When over ha l f the original proteinconten t is lost th e
2.
dentine becomes softene d.
e) All calcium salts remain in softened dentine, providing data by means of x-rays.
HARP SEAL DENTINE
Deciduous teeth are resorbed prior (80%) to and after birth inMa r c h. Permanent teeth eruption is 38% completeat birthandby weaning (threewe e k s) is completed (Stewa r t and Stewart 1987a). A phocid postnata l tooth represents al l dentinal growth since prenatal tooth formation (Fisher 1954). The neonatal li n e in harp seals is formed at birth (S t ewa r t andSt e wa r t 1987a).
Fisher (1 9 54) suggests a common causative factorfor harp seal dentineannul ibecause all of his study sa mpledisplayed a similar pattern and structure . Also, Fisher foundth at harp seal dentineincremental annuli (Figure 2.1)are often crowded and indistinct after about twelveyearsma k i n g interpretation difficult. This crowding results fromthe decrease in th e pulp cavityas dentineis deposited yearly.
Fisher (1954)observed thesameregular annual pattern of dentine la y e r formation for all ages of both sexes. Bowen ee al. (1 9 8 3) al s o sa wno difference in the pattern of GLGs for maleand female harp seals. Th e y (1983 :1434) report:
at each age the translucent IGLbegins to formin June-Julyandre a c h e s its maximumthickness in February-March, correspondingto the timeof harp sealbirths. The outermost IGL in a typical GLG, the inter globulardentine. is forme din April and
29
earlyMay, the periodwhenharp seals undergo their annua l moult. The middle IGLoropaque band is fanned inMay and Jun e. duringthe time when lIIOst harpse al s ar e mi grating totheir s\1IIlIlIerfee di n grang e. The regular patternof GLGformation al l ows th e di v i s i on of the ye a r into three t ime peri ods reflecting ea ch IGL's developmental period. Anymode rnor archaeolog icalharpseal co u ld bepl aced in one of the s e thre e t.ime pe riods basedon the la s t IGL . However, t.h e t.ranslucent. IGL's devel o pmenta l period spans nine mon t.hs and includes the southward and nort. h wa r d migrat i ons t.o the Port auCho i x area .
The separa t i on of these two migrat i onsat Port:.auChoix ha s implicat i ons fordef iningseasona lity of archae o l ogi ca l sites. Therefore, some means to subd i vide d th e t.ranslucent la y er must be developed in or d e r to sep a r a t e the ewe migra tions. The trans luce n t. dent.ine may devel o p at a predictable rate thuspermitt. ing an estimation of percentage de v e lopme n t at December compared to late February/~a rch.
Anothe rpossibility isthat similarto GLG format iont.he IGLa areforme d bya regularpat.t.ern of la ye rs. Anumbe rof modern can i ne secti onswi l l berequi red to attemptt.his deciph e r i n g of the t.ranslucent. la ye r . But . firs t. a re v iew of the liter at.ur eondentineanalys is formanunals mu s t beconducted.
au
Figure2.1Diagrammatic CrossSection of a Harp SealCanine Sec tion
31
CHAPTER 3 METHODS: REVIEW AND DISCUSSION: MODERN SPECIMENS
Wildlifebio logists age marine andterrestrial manmals usin gthetooth den t i n e/ceme n tum annuli meth od{Kl evez a l and Kleine nbe rg1969; Mor ris19 721. TIlis chap t e r dis cusses eooth se lection andtheva rious techniques utilizedin sect i oning . A wide diversity of toot h secti on preparationeechniques are ava i l ab l e to therese a r c h e r . Decalcifying , sawing, microtome se c t i o n i ng , grinding, and st.aining are some of t.h e s e t.echniques. Once the section is prepared a numberof vi e wing tec hni qu e s are available to analyse the dentine/cementum annul i. Either transmittedor reflectedlight can beuti l iz ed wi t h some formot magn ifica t ion(i. e. bi n o cul a r microscope). Pbor.ograpbi c techni que s (i.e.pict u re sor sl i des) to enlarge or enhance ene imag@sar e also ut i lized .
Cementum or Dent ine
Based ont.heli t.er a t.ur e reviewed cement.um was prefe rred over dent ine for agin g te rre st. rial mammals wh e re a s ce mentum and dentine were equally util i z ed formarinemammals. Only four marine mammalsof thetwent y - n i ne mammal species (t we nty- on e terrest.rial and eight marine) we r e aged solely on the basis of dentine annuli. No terrestrial mammals wereag ed by dentine althoughdentine annuli werevi s i b l e in a number of the teeth examined. McEwan (19 6 3:112 )obse rved annuli in the dentine of barren groun d caribou but noted the first thre e
32
annuliwerenotve ry dist inct. Marks andBri ckson (19 66: 408) re ported that dent i ne in black bea r prov i d e unre liable re adings compa r ed to the kno wn age. only 71 1"of the she e p teethsectionedbyTurner(1 977: 213)dis pla y ed de ntineannuli. The major problem wi th inte rp re t i ng dent ine annu l i is thatthelaye rsbecome compr e s sedanddifficult to distinguis h as th e pulp cavi ty fills. Keny o n and Fiscus (19 6 3 :2811 reported that the Ha wa i ian monk se a l's puLp cav ity was comp l etely filledbyage fourorfive. The grey seal'spulp cavi t y also fil l s in duringthe fi r s t fewye a r s of life (Hewer 1960:960). Inothe r marine mammals such as th e steller se a lion the pUlp cavi ty is not filled until fif t e e n year s or old e r {Fi scu s 1961: 2181. Fisher (1 9 54:301sta t e sthatann uli arecrowdedand indistinct after the twelfthye a r butup to th irty - f our annuli have been dist i ngui shed in harp seal canine s.
Ce mentumis pre f e rred ove r dent i n e forag i ng mostma:rmals because in olde r indiv idualsthe read i ngsar e consideredIIIOre reliable_ Howeve r , harpse al s only produc e a thin ce men t um la ye r andthe r et'or ere s e a r che r s st ud y thedent i n e. Bowe n ee al. (19 8 3 :143 2) state tha t rel iable age estimate s from cemen t um growth lay ergroups (GLGs) are notpossibleforharp seal. Althoughvi s ibleintooth sections, thecementum annuli aremos t lyindistinct. The cementum annuliof ringedseal are als o not distinct enough to be re liabl e for aging {Smi th 19 73:81 . Smit hreportsaging bycementumannul i when thepulp
33
cavity is tu l l of dentine. Using cementum annuli McLaren (1958:8) aged one male ringed seal at around forty-three years.
Longitudina1 Sections Versus Cross-sections
The use of longi tudinal or cros s-secti ons dentin e/ce ment um annuliva r ies amongresearchers . cr a ighe a d et al. (1 970;356) state th a t longitudinal sections are sup e r i or to tr an s ve r s e sections for distingui shingannuliin grizzlybears. Miller (19 74: 4 9) believes for ba r ren ground caribou "t h eoccurr e nceatannuli and the possible sp l i e ti ng, mergi ng , or disappearanceof an annuli"are best determinedin longitud inal se ct ion s. These changes in annuli cou l d be mis s e d incross -se c t i o n s accordingeoMiller. Ingreywo l ves th eannul iare most di stinct i veand false annul i most obviou s inlongitudinal sections (Good wi n and Ballard 1985 :315 ). The longitudinalsectionsalso pro vided consist e n t age resul t stor grey wol ves . Hemming (1969: 553 ) considered long i t udinal se c tio ns best fo r dall sheep because the ce men tumthi cknes s va r i e s on the toot h root. Harris (1978: 95 ) also found lon g i t udinalsections the easiest to interpret fo r agingre d foxes because the longer section prov ided a more accurate count.
Cros s - s e c t ion s are preferred by some researchersbe caus e mor ecr oss-s ect ions than longitudinalsections canbe prepared
34
per tooth (BricksonandSeliger 1.969:385). Thomas and Bandy {1.9 73: 2 3 4} while studying black-tailed deer concluded that cross-sections exposed the entire circumference while lo n g i t udi n a l sections only reveal two segments of the circumf e r e n c e . In mule deer teeth Brickson and Seliger (1.9 6 9 : 38 5) noted that while often missing in lo n g i t ud i n a l sections the most distinct area of cementum annuli is always found in the cross-section.
Tooth Preferenc.e
Teeth producing the most suitable/readabletooth sections va r i e s among mammal species and with researcher preference.
Teeth aged byth e dentine/cementumannul i technique include cani n e , incisor, premolarand molar. Wolfe (1 9 6 9: 4 28 ) found that moose maxillary teeth annulishow greater separationand regularappearance than the same individuals mandibular teeth annuli. Sergeant and Pimlott (1.9 5 9: 31.6 ) used the first incisor for aging moose because i t is the largest and first to erupt of the four incisiform eeeen. But, Wo l f e (1.9 6 9 : 4 2 8) utilized the first true molar wh i c h is the first permanent tooth to erupt in moose. Fogi and Mosby (1 97 8: 4 4 4 ) used the third molar of grey squirrels because of that tooth's thick cementum deposit. Canines are preferred fo r seals because they have the largest pufp cavity.
35
TOOTH SPEC:IES SOORCE
canine bobcat Crowe 1972
canin e coyotes Linhar tand
Knowlton19 6 7
canine red. fox Allen 1974
Harris 1970 canine cape fur seal Fletemeyer 1978 canine steller sea lion Fiscus1961
upper canine black be ar Marks and
Erickson1966 upper canine grey wolves Goodwin and
Bal l ard1985
upper right badger Croweand
canine Strick land 1975
upper right fur seals Scheffer and
canine Peterson19 6 7
upper right Alaskan fur seal Chiasson 1957 canine
upper right harbour seal Mans f i e l d and
canine Fisher 1960
upper right Hawaiianmonk seal Kenyon and Fiscus
canine 1963
incisor white-taileddeer Lockard 1972
incisor moose Sergeant and
Pimlott1959 upper incisor common vampireba t Li nha r t 1973
first incisor muledeer Ericksonand
Se liger1969 Lowand MeT. Cowan
1963 first incisor barrenground Mc Ewan 1963
caribou
Table 3.0 Preferred Teeth for Sectioning (cont.inued next pa g e )
36
TOOTH SPBCDS SOtJRCB
fi r s t incisor elk Ke i ss 196 9
fir s t inc i s or moos e Gasa wayecal.
19 78
fir s t incisor nronghorns McCUtchen 1969
fir s t incisor dal l she ep HetnDinq1969
pr emol ar redtox Harris 1978
first ore molar blackbear Willey 1974
four t h nremolar bis on Novakowski 19 6 5
lower fourth griz zly bear Craighea d eeal.
premol ar 1970
molars ba r r e n ground Miller 197 4 caribou
molars beaver Van Nostrandand
Step h e n s o n 1964 molars white -tail edde er Lockard19 72
mola rs red fox Harrri s 1978
fi rs t molar white-t aileddeer Ransom 1966 fir stmolar reddeer Mi t chell19 6 3
first molar moose Wolfe 19 6 9
thirdmolar grey squirrel Fog1 andMosby
1978 lower thirdmolar griz zlybear Mundyand Ful l e r
19 6 4 lowe r thirdmolar ground squirrel AdamsandWaek i ns
196 7 Tab l e 3.a (continued) PreferredTe ethtorSectioning
37
Te chnique s for Preparing Tooth Sections
A number of eoocn se c t ion preparacion Cechniques ar e avai labl e Co faci l i cace and enhance cbe reading of denci ne ! c e mentumannu li. The fol l owin g pres enc e a sampleof this wide range of Cechn i ques that hav e been ut i lized. on modern mammalian te e th.
1) Decal c 1~iDgTeeth
Teeth are decal ci fied to fa c i l i tate the successfu l cutting of too t hsect io ns. Diluteacids ar eus edtodis s olv e the calc i u m pn c epnaee mine r a l s co ntained in enamel, de ntine and cementum(Hi l l s on1986:16 9). Butextendedexposuretoth e decalci f y ing agent can reduce the stai ni ng qual iCy of the rema i n i ng toothtis sue (Bhaska r 1986:4591. Or g ani c acidssuch as formic and t.richlo roacetic have a le s ser impact on the sta i n ing qualityofthe tissue (Hil l s o n19 8 6: 169).
acbcac (Cr o we 197 2:1330) , elk (Ke iss 1969:1 76 ) and mul e deer(Eri ck so nand Sel i ger1969:386) teethwer e demine r alize d in formicac i d . A to.ixcur eof formalin, formicacidand wate r was used oncoumo n vampire bat (Li nhart 1973:494). coyotes (Linha r t. and Knowlton 19 6 7:36 2 ) and Nort.h American shee p (Tu rne r 1977:212) teeth. The mixture use d by Turnerwas five parts formi c acidto on e part formalin to 20 parts distil led wa t e r. Allen (1 97 4:1 53) decalc ified red fox canine in 77t water, 20\' formicacidand3\ formaldehyde. A solut i o n of lOt
3 .
formic acid and 5\ formal i nwas used by Thomas (1 9 77 : 207) to decalcifybear, caribou, cougar, dog, mountain goat, human, muskoxen, North American deer, roe deer and wolf teeth.
Californiaground squirrel teeth were soaked in Rartman- Ladden decalcifying fluid th a t contained RCI and ch e l a t i n g ag e n t s (Ada ms and Watkins 1967:836 ) . Goodwin and Ballard (1985: 314) decalcified grey wolves te e t h in 10 \ BCL that containedchelatingagents. Chelatingagentshelp to preserve th e staining properties of the remaining tissue (Hi lls on 1986:169 ) . ROO,a type of rapidbonedecalcifier , wasus e d on American badger teeth by Crowe and Strickland (1975:26 9). Stephenson (1977:1578) used 5\ nitric acid on otter te e t h while for blackbear Stoneberg and Jonkel (19 6 6: 41 1 ) utilized 1St nitricacid and30 t formic acidon blackbear while Harris (197 8:9 -4) used 3\ni t ri c acidin10\ fo rma l d e h y d eon red fox.
Nitric acid accordingto Turner (1 9 7 7:213) obliterated the distinct annuli of North American sheep. Morris (1 972:8 7) also not esthatprolongedde c a l cify i n g in 5t nitric acid will caus e te e t h to becomehistologically fe a tur e l e ss.
The time required to decalcify the teeth varied from hours to days depending on the solutions us e d. The ROO rapid bone decalcifier usedonbadgerteethre qu i r e d fourhours or le s s and had the potential to over- d e c alc i f y (Cr o we and St ri c k l and 1975:270) . Thirty hours are requiredto decalcify California ground squir rel teeth using Hartman-Ladden decalcifying fluid (Adams and Wa t k ins 1967:836) . Caribou
39
teeth required 18 to 72 hours, depending on age and whether incisors or molars, using Miller's (1 9 74 : 4 8) nitric acid soluti on . On e of the longestdecalcifyingperiods was the 13 to15days required forred fox teeth (Al l e n 1974 :15 3 ) . Fogi and Mosby (1 97 8 : 4 4 4) preferred formic acid-sodium citrate solution because of a shorter decalcifying time than nitric acid and Hartman-LaddenfLu Lds.
i t) Resin Embedding
Embedding teeth in resin and similar materials strengthens the teeth to withstand the effectsof sa wi n g and grinding. Grizzly bear toothroots were placed in dental rock prior to sectioning by Mundy and Fuller (1 96 4: 864 ). Bow (1966:438) embedded sperm whale teeth in Ciba 'Araldite' casting resin which required a curing time of approximately four hours . Drymule deer teeth were soaked inuncatalyzed resin and all teeth embedded in catalyzed resin by Erickson and Seliger (1 9 6 9 385) . The resin was allowed to hardenovern i g h t and thenheat harden at sixty degrees celsius forthree to four hours. Keiss (1 9 69: 176 ) alsoembedded elk teeth in catalyzed resin while Marks and Erickson (1 96 6:3 90 ) used Bioplastic for black bear and for caribou teeth Miller (1 9 74 : 4 8 ) utilized plastic. Miller etal. (1988:138)embedded human teet h in polyester casting resinin s i d e butyrate plastic tubi ng.
40
i i i ) Types of Saws
Researchers us e a wide variety of saws to cut their tooth se c t i o n s (s e e Table 3.11.
Erickson and Seliger, and Miller us ed the Gillings- Bronwill thin sectioning diamond saw machine. The unit ' s cu t t i n g speed was five rpm while cooled and lubricated by water (Er i c k s o n andSeliger 1969:386) . Amajor problem with us i n g saws is the destruction of a sectionof tooth withevery cut. Erickson and Seliger (1 96 9 :3 8 6 ) report a 305 micron se c t io n was destroyedbetween each section cut.
iv) Razo r sectioni ng
Straight edge razor sectioningbyhand was used by Allen (19 7 4:1 5 3) on red fox teeth and Fogl and Mosby (l978:445) on grey squirrel te e t h. Thomas (19 7 7: 207) cut some of his sections with a razor blade by hand. A problem with razor sectioningwas th a t a numberof sections are slanted making photographs almostimpo s s i b l e (Fogt and Mosby 1978:44 7 ) .
41
SAW Tn'E SPE C:IES SOURCE
hacksaw moose Wolfe 1969:428
diamond blade moose Wolfe1969:428
lapidary
finetooth moose Gasaway at al.
lapidary 19 7 8:559
diamond dental black bear Marks and
disc/wheel Erickson 1966 : 3 9 0
diamonddental dall sh e e p Hemming1969:553 disc/wh e e l
diamondrocksa w A1as kan fur se a l Chia s son 195 7 : 31 1
bandsaw moose Se r g e ant and
Pimlot t 1959:316
jewel l er's moose Sergeant and
ci r cul a r saw Pimlott 1959:316
jeweller'ssaw se al Fisher and
Ma c k e n z i e 1954:5 35
toothsaw pronghorn McCut chen
196 9:173 Niclas Bon e and grizzly bear Mundyand Fuller
Toothcut t i n g 1964: 864
machine
Dr e me l electric black bear Willey19 74:9 8 scrollsaw
thin sectioning mule deer Ericksonand
sa. gej.Lcrer-1969: 384
thin seceioning elk Keiss 1969:176
sa.
thinse c t i o n i n g ca r ibou Mi l l er 19 74:481 sa.
Gillings- Hameo ringedseal smith 1973:3 thi n sectioning
machine
smallci r cul a r seal Department of
sa. Fisheries
Tab l e3.1 Sawsuse d toSect i onTe e th
42
"7) lIicro~cmesec~ioning
Microtornes cut thin sections of organic tissue to permit microscopic study of ebe t.Ls sue. Microtome sect.ioning, including th e standard paraffin or parlodion embedding cechnique or the freezing cechnique, is a roucine hiscologic procedure. Two embedding techniques used on mammal teet.h are cryoform and paraffin wax. The freezing microcome method eliminates the need for tissue dehydration and is more rapid t.hant.he scandard technique (Fancy1980:243).
Bobcat. (Crowe1972:1330)and North American sheep (Turner 1977:213 ) teeth embedded in cryoform were sect.ioned on an Int.ernational-Harris cryostat.. Grey wolves (Goodwin and Ballard 1985: 314 ) teeth were sectioned on a Minotome Microtome-Cryostat whileMiller used an Ames Tissue-cryostat for caribou. Stoneberg and Jonkel (1 9 6 6: 4 1 2) embedded black bear teeth in paraffin wax and sectioned them with a hand- operated sledge microtome. Harris(1 9 7 8: 9 4 )cut red fox teeth sections with a freezing microtome technique.
vi) Gr inding Sections
Teeth are ground to produce the actual section or to remove saw cut marks and/or reduce the section' 5 thickness.
Fleterneyer(1978: 695)produced cape fur seal tooth sect.ions by grinding with360grit carbide paper, pumiceandwhiting. A number of sawed sections were polishedand reduced through various grinding methods. Marks and Erickson (1966:390)
43
ground black bear t.eet.h sections on a commercial carborundum stone with water. Whit.e-tailed deer teeth (Loc ka r d 1972:48) were smoothed using a fine grit carborundum wheel mounted on a bench grinder and finished by a very fine aluminum oxide wheel hand grinder. Sections were ground by Frost. (1 9 5 8: 2 7 3 ) using No. 320, 360 or 400 grit. carborundum abrasive paper while Fisher and MacKenzie (1954:536) used a grinding machine with two fine grit carborundum ar.ones . Van Nost.rand and Stephenson (19 6 4 :431) groWld beaver tooth sections with a 4, 000 rpm fine texture circular grindstone.
During grinding of the tooth section water or a water spray was used ec eliminate a number of potential problems.
These problems include dust, odour and burning of the toot.h, cracking and overheating of the tooth (Ga s a wa y ee al. 1978:559; Lockard 1972:48) .
vii) Staining
Numerous researchers stain tooth sections ec increase the contrast between ene opaque and translucent annuli. The increased contrast improves the readability of t.he dentine!cemeneumannuli. Although a wide range of stains and staining techniques have been tested, Peragon and Harris' hematoxylin are most conunonly utilized.
Goodwin and Ballard (1985 :314) tested nineteen stains on grey wolf tooth sections and preferred Harris' modified hemaeoxylin stain with hot bath. They state that t.his stain
44
produced consistently detectable and readable cementum annul.L. However,Thomas (1977:207-2~O ) found cationic stains superior to the more commonlyus e d hematoxyl instains. Metachromatic ca t i o n icsta i ns such as tol u i d i n e blue, thionin , and crystal viole t werepreferred. These stains provide more consistent results and producedcon t r a s t i n g annuli co l ou r s. Ce me n t um annuli with the least amount of background colour result ed from using toluidine blue stain. The stains display va r i abi l i ty between species, teethandth est a i n ing testsbut metachromatic stains had greatly less variability than hematoxylin st a i n s.
45
STADI SPZCUS SOURCE Peraaon cCXlIDOn vampireba t Linhart 1973:4 9 4
Peragon bobcat. Cr owe 1972 :133 1
Peragon coyotes Linhart and
Kno wl t o n 1967:363 sereacn red fox Allen 1974: 15 3 Peragon North Americ an Turner197 7 :213
sheep
Hematoxylin mul e deer Erickson and.
seaieee1969,386
HematoXYlin elk Keiss1.969:176
Hemat.oxylin grey squirrels Pogl andMo s by 1978 :445 Hematoxylin black bears Stonebergand
Jonkel 1966 :412
Hematoxylin otter Stephenson
1977:1 5 78
Hematoxylin red fox Harris 1978:94
Hematoxylin gri ZZly bear craigheader ef . 19 7 0:356
Hemat oxylin grey wolves Goodwinand
Ballard 1985: 314 Table3.2 ToothSectionStains
MethodsofViewin g TeethSe c t ions Two methodsof viewing teeth sections are:
il magnification (i.e. binocular microscopeI using either transmitted or reflected light
i i) pboeomicroscope.
Transmitted light. wa s us ed for black bear (Marks and Erickson 1966:390) and ringed seal (McLaren 19 5 8:5 ; Smith
46
1973:3) eeeen sections. (:bias son (1957:316) suggest.s enae t.hick sect.ions could be made clearer for viewing by soaking in cedarwood oil for a minimum of t.wenty-four hours. Transmitted light was considered bet.t.er t.han reflected light. by Marksand Erickson (1966: 391) for counting black bear cementum annuli. Reflected light was used by Mundy and Fuller (1 9 64 : 8 64 ) on grizzl y bear while Lockard {197 2: 4 8) and Ransom (1966 : 1 98 ) viewed white-tailed deer teeth. Sergeant and Pimlott (19 5 9:3 1 6) also used reflected light for moose tooth sections . Researchers utilized various types of microscopes and magnifications to enhance t.ooth section int.erpret.at.ion. A dissecting scope and 40X magnificat.ion was used by Allen (1 9 7 4: 1 5 3) fo r red fox and Mundy and Fuller (1 9 6 4: 8 64) for grizzly bear toot.h sections . Sect.ioned fur seal eeeen were on l y magnified t.nr-ee times by Anas (1 9 7 0:845). For moose te e t h Gasawayet: al. (1 9 7 8: 5 5 9)used a binocularmicroscope at 10-30X magnification. Sergent and Pimlott (1 9 5 9 : 316) viewed alcohol moistened moose teet.h sections wit.h 10-40X and measured the annuli widthwit.h a eyepiece mounted calibrated micrometer. Wolfe (1 9 6 9 : 4 2 9) used oi l or colourless nail polish to enhance the annuli when viewed at 20X with a binocular microscope. Turner (1 9 7 7: 2 1 3) viewed sheep teeth sections at. 40-100X magnification with transmitted light us ing a green filterand a binocular microscope.
Magnificaeion of 160X from a Zeiss Standard GFL fluorescence microscope was ueilized byHemming(1 9 6 9:5 5 4) for
47
aging dall sheep teeth . The microscope wa s equipped wi t h barrier filters53/47 . exciter filterIII and an Osram high- pressure mercury la mp . Linhart (1 9 7 3: 4 9 5) us e d lOOX magnification for vampire bats while using a compound microsc opeand40X to100Xmagnificationforcoyotes (Linhart and Knowlton 1967:363). Miller {1 97 4 :481 re a d ca r i b ou se ct i on s at100Xto40 0 Xmagnification with a Bausch and Lomb Zoom Microscope.
Bow{1966:4381photographedsperm whaleteeth with extra fine grained sl ow speed (5 0 A. S .A.) film. Fur seal te eth sections were photographedat 5Xmagnificationby Schefferand Peterson (1 9 6 7:36). Erickson andSe l i g e r (1969: 386 )examined 95 micron thick mule deer teeth sections wi th a Zeiss photomicrosc ope . A Zeiss exciter filter BG 12 and a Zeiss barrierfilter53/44 were used with transmitted ultravi olet light. Erickson and Seliger con s i dere d the technique promis i ng since the cementum annuli fluoresced to be distinguishable . Photomicrographs were taken of all grizzl y bear teethse c t i on s examined bycr a i g h e a d ee az . (1 9 7 0:35 6). Mi ller ee ez. (1 9 8 8 : 138)made photomicrographsof human tooth sections using Kodak Panatomic X filmand90X magnification under sub d u e d li g h t. The ce me n t um annul i we r e counted by projectingth e photomicrographs on t o a screen.
Comments
48
Selecting the methods to produce and examine tooth sections varies with researcher preferences and animal species. A researcher could follow the methods outlined for a specific species but some experimentation is required to determine what technique produces the desired results for an individual researcher. For example, unaltered annuli are clearly distinguishable to some researchers while others require stains to enhance the contrast between annulus. Selected techniques will also be determined by what resources are available to produce the sections.
Accurate Absolute Age Resul ts
The use of known age specimens is the only way to verify that the dentine/cementum annuli aging technique produces accurate absolute age results. To date, verification of the dentine /cementumtechnique is generally based on limited known age samples. Terrestrial manmal samples of known age include 42 beavers (Van NostrandandStephenson 1964:430). 30 coyotes (Linh a r t and Knowlton 1967:362), 16 mule deer (Er i c k s o n and Seliger 1969:384),18 elk (Ke i s s 1969:176) . 95 red fox (Al l e n 1974:152) and 63 grey wolves (Goodwin and Ballard 1985:313).
Marine mammals of known age used to test the technique include 40 cape fur seals (F l e t e mey e r 1978 :6 95 ) and 390 fur seals comprised of 120 males aged two to fiveand270 females aged three to eleven (Ana s J.970;845).
One important factor affecting accurate absolute age
