Variable Selection

It is likely that the ossuaries I examined during fieldwork in Papua New Guinea will never again be visited for the purposes of recording skeletal data. This was a major factor in determining which variables were to be included in the present study, and I initially wanted to record as many as possible. There had to be a compromise, however, between the total number of skeletal variables that it was

possible to record and the number of variables that I could successfully manage given time restrictions and the aims of the study. I therefore chose to ignore the postcranial skeleton and concentrate instead on recording a wide range of cranial and mandibular variables. The variable list initially decided upon before commencing fieldwork included 67 cranial and 10 mandibular metric variables, 18 cranial and three mandibular non-metric variables, 12 cranial anatomical variables, and one skeletal (cribra orbitalia) and one dental (enamel hypoplasia) pathology. The pathologies were included largely because of my personal interests.

Two factors were paramount in deciding the initial composition of the metric variable list. First, I wanted to maintain a broad range of facial, vault and mandibular variables which would reflect the exploratory nature of the present study. Secondly, I wanted the option of being able to compare the results of my own investigations with data recorded in other studies, particularly those of Brown (1982) and Pietrusewsky (1984, 1986) on prehistoric and contemporary Australian, Melanesian and Polynesian samples. Although I have since decided to abandon this latter option for reasons already discussed, the variable lists of Brown (1982) and Pietrusewsky (1984, 1986), as well as those of Yamaguchi (1967), Howells (1973a, 1976a), Thorne (1975) and Giles (1976), and the observations based on these, were carefully considered when deciding the final metric variable list.

In selecting the non-metric variables to be recorded, I took advice from Dr. Colin Pardoe on the basis of his investigation of non­ metric cranial variability in prehistoric Australian Aboriginal populations (Pardoe 1984) . From his original list of 45 variables, Pardoe suggested 18 which he believed might prove useful in the investigation of population variability in Papua New Guinea.

The anatomical variables identified by Macintosh and Larnach (1973) as distinguishing Australian Aboriginal cranial samples from Papua New Guinea samples were included for two reasons. They not only enable some comparative comment on the anatomy of the cranium, they also allow an investigation of their discriminatory power when a range of truly regional samples from Papua New Guinea is compared with east coast Australian samples, instead of using the single, aggregated sample from Papua New Guinea used by Macintosh and Larnach (1973) .

Modifications to the variable list were inevitable. It became apparent after recording data from the first three or four ossuaries that mandibles were rarely preserved intact. Further recording of the metric and non-metric mandibular variables was therefore abandoned. Similarly, teeth were rarely if ever found intact within their maxillary alveoli, so that it would have been impossible to relate the incidence of enamel hypoplasia to any specific individual or subcategory within the ossuary samples. The recording of enamel hypoplasia was therefore also dropped from the variable list. Lastly, a further three metric cranial variables (nasofrontal articulation, nasion-prosthion and glabella prominence) were added to the variable list immediately prior to the commencement of fieldwork.

The final list of 7 0 metric, 17 non-metric and 11 anatomical cranial variables recorded in the field and presented in this study are given in Tables 1, 2 and 3 respectively. All of the metric variables are chord measurements recorded directly from the crania using standardised equipment (GPM sliding, spreading and coordinate calipers). All linear dimensions were recorded to the nearest millimeter. Descriptions and definitions of all the variables recorded are given in Appendix 1. The presence or absence of cribra orbitalia was also recorded following Webb (1982), although his three

Maximum bi-parietal breadth MAXBIP1 Basioccipital breadth BASOCCB

Maximum cranial breadth MAXCR Basion-asterion BASAST

Glabella-opisthocrAnion GLOPC Lambda-bregma LABREG

Nasion-opisthocranion NOPC Parietal subtense height PARST

Glabella-lambda GLLA Bregma-parietal subtense BREGPARS

Nasion-lambda NLA Lambda-inion LAIN

Basion-bregma BASBREG Lambda-asterion LAAST

Basion-nasion BASN Auriculare-bregma AURBREG

Basion-nasospinale BASNS Auriculare-glabella AURGL

Basion-prosthion BASPROS Auriculare-nasion AURN

3asion-lambda BAS LA Auriculare-nasospinale AURNS

Basion-inion BASIN Auriculare-prosthion AURPROS

Bi-auriculare BIAURIC Auriculare-zygomaxillare AURZYGOM

Bi-asterion BIAST Auriculare-lambda AURLA

Glabella-bregma GLBREG Auriculare-inion AURIN

Nasion-bregma NBREG Auriculare-opisthion AUROP

Metopion height METHT Auriculare-basion AURBAS

Nasion-metopion NMET Auriculare-asterion AURAST

Maximum supraorbital breadth MAXSORB Nasion-inion NIN

Minimum cranial breadth MINCR Nasion-nasospinale NNS

Minimum postorbital breadth MINPORB Nasion-prosthion NPROS

Bi-zygion BIZYG Nasal breadth NASB

Bi-zygomaxillare BIZYGOM Orbital height ORBHT

Bi-maxillofrontale BIMAXF Orbital breadth ORBB

Maximum bi-frontomalare MAXBIFRO Cheek height CHKHT

Bi-stephanion BISTEPH Bi-ectoconchion BIECT

Opisthion-inion OP IN Bi-dacryon BIDAC

Opisthion-opisthocranion OPOPC Alveolar length ALVL

Opisthion-lambda OP LA Alveolar breadth ALVB

Opisthion-asterion OPAST Mastoid length MASTL

Opisthion-nasion OPN Mastoid width MASTW

Foramen magnum length FML Mastoid breadth MASTB

Foramen magnum breadth FMB Nasofrontal articulation NASOFRON

Bi-mastoidale BIMAST Nasospinale-prosthion NSPROS

Basion-sphenobasion BASSPH Glabella prominence GLABPROM

Epipteric bone Asterionic bone Lambdoid wormians Post-Condylar canal Vesalian foramen Ovale-Spinosum confluence Pterygo-Basal bridging Accessory Palatine foramen Palatine torus

Palatine bridging (medial) Infraorbital foramen

Infraorbital suture

Spheno-maxillary articulation excluding the zygoma

Lacrimal foramen Trochlear spur Zygo-facial foramen Auditory exostoses

Table 3. Larnach and Macintosh anatomical variables

Superciliary ridge development Zygomatic trigone development Phaenozygy

Degree of vault keeling

Transverse occipital torus development Rounding of the infraorbital margin Anterior nasal spine development Median frontal ridge development Parietal bossing

External occipital protuberance development Supramastoid crest development

categories of severity (porotic, cribrotic and trabecular) were not individually recorded.