Fig 1.
Individual ‘HT4’ Hirota site crania.
1) Frontal View; 2) Right-lateral view; 3) Superior view.
Fig 2.
Morphological comparison of Doigahama and Hirota example crania.
A: Doigahama sample DG8; B: Hirota sample HT16. HT16 shows an extreme deformation of the posterior region resulting in a flattened and squared morphology, combined with asymmetry of the neurocranium.
Fig 3.
Map of the Japanese archipelago and Kyushu Island study region, including Tanagashima Island and the Yamaguchi region.
Sites utilized in this study displayed as numbers: 1) Doigahama, Yayoi; 2) Yamaga, Jomon; 3) Einomaru, Jomon; 4) Goryo, Jomon; 5) Hirota, Yayoi-Kofun. Map created utilizing the ‘KASHMIR 3D’ program, utilizing public domain, open access base data from the Geospatial Information Authority of Japan (GSI).
Fig 4.
Topographic maps of each site utilized in this study and surrounding areas.
Map created utilizing the ‘KASHMIR 3D’ program, utilizing public domain, open access base data from the Geospatial Information Authority of Japan (GSI).
Fig 5.
Examples of typical burials at the Hirota site, displaying large numbers of shell accessories.
1) Individual ‘HT3’ in this study; 2) Individual ‘HT9’ in this study.
Table 1.
Materials list.
Fig 6.
Geometric Morphometric (GMM) workflow utilized in this study.
Fig 7.
Principal component morphospace plot of the first principal component (PC1) (x axis) and PC2 (y axis).
Colors denote site groupings: green: Hirota; blue: Doigahama; red: Jomon of Kyushu. PC1 and PC2 contribute 75.9% and 9.0% of the variance, respectively.
Fig 8.
Summary of shape variation along PC axes (PC1–3) of sagittal outlines, utilizing the ‘PCcontrib’ function.
The representative shape of PC1 displays flatness of the posterior parietal and occipital regions as well as the lengths from the posterior edge of the mastoid process to the posterior end of the crania. PC2 is associated with the height of the external occipital protuberance and lateral shapes of the occipital bone, such as the position and shape of the occipital bun. PC3 is associated with the flatness of the posterior cranial outlines.
Fig 9.
Principal component morphospace plot of PC1 (x axis) and PC2 (y axis) for sex-estimated differences between groups.
Hirota: female-unfilled green, male-solid green; Doigahama: female-unfilled blue, male-solid blue; Jomon: female-unfilled red, male-solid red.
Table 2.
MANOVA output for site- and sex-based group comparisons.
Table 3.
Results of MANOVA pairwise comparisons for site- and sex-based group comparisons.
Fig 10.
Box plots of PCA scores (PC1 (lower) and PC2 (upper)) between sites (Hirota–Jomon–Doigahama). Colors denote site groupings: green: Hirota; blue: Doigahama; red: Jomon of Kyushu. PC1 (75.9% of the variance) shows that the spread of variability and mean shape of Hirota crania are plotted differently than those of Jomon and Doigahama.
Fig 11.
Box plots of PCA scores (PC1 (lower) and PC2 (upper)) between sex groupings (by site and sex). Colors denote site groupings: green: Hirota; blue: Doigahama; red: Jomon of Kyushu. PC1 (75.9% of the variance) shows that the spread of variability and mean shape of Hirota crania are plotted differently than those of Jomon and Doigahama.
Fig 12.
Comparative thin plate spline output (Hirota and Doigahama).
Hirota shows shorter and flattened occipital outlines.
Fig 13.
Comparative thin plate spline output (Hirota and Jomon).
Hirota shows shorter and flattened occipital outlines.
Fig 14.
Comparative thin plate spline output (Hirota and Doigahama).
Doigahama and Jomon show similar occipital shapes.
Fig 15.
Comparative thin plate spline output (male and female Hirota).
Fig 16.
Comparative thin plate spline output (male and female Doigahama).
Fig 17.
Comparative thin plate spline output (male and female Jomon).
Fig 18.
Morphometric mapping (upper) and sliced segmental extraction (lower) of sample HT 16. It has flat and short crania displaying depressions along the sagittal and lambdoidal sutures. MM captures the suprainiac depression and depressions on the right side of the lambdoidal suture. SSE captures the depression of the sagittal suture, shown in yellow/orange. The occipital area shows asymmetrical protrusion, shown in white/blue. Color representations: areas of depression red<yellow<green<blue<white areas of protrusion.
Fig 19.
Morphometric mapping (upper) and sliced segmental extraction (lower) of sample HT 12. It has flat and short crania displaying depressions along the sagittal and lambdoidal sutures. MM and SSE capture the suprainiac depression and depressions on the sagittal and lambdoidal sutures. Both sides of the suprainiac depression show two projections, shown in yellow/orange. The occipital area shows asymmetrical protrusion, shown in white/blue. Color representations: areas of depression red<yellow<green<blue<white areas of protrusion.
Fig 20.
Morphometric mapping (upper) and sliced segmental extraction (lower) of sample HT 6. It has flat and short crania displaying depressions along the sagittal and lambdoidal sutures. MM and SSE capture the suprainiac depression and depressions on the sagittal and lambdoidal sutures, shown in yellow/orange. Both sides of the suprainiac depression show two “mountain-like” protrusions. The occipital area shows asymmetrical protrusion, shown in white/blue. Color representations: areas of depression red<yellow<green<blue<white areas of protrusion.
Fig 21.
Morphometric mapping (upper) and sliced segmental extraction (lower) of sample HT 15. It has a flat, short crania displaying suprainiac thinning (as demonstrated by the hole and surrounding area of visible thinning showing concaved depression). Depressions along the sagittal and lambdoidal sutures are also present. MM and SSE capture suprainiac thinning and depressions on the sagittal and lambdoidal sutures, shown in yellow/orange. The occipital area shows asymmetrical protrusion, shown in white/blue. Color representations: areas of depression red<yellow<green<blue<white areas of protrusion.
Fig 22.
Morphometric mapping (upper) and sliced segmental extraction (lower) of sample DG29. It shows no evidence of intentional cranial modification, as displayed by the lack of depressions along the sagittal and lambdoidal sutures. Color representations: areas of depression red<yellow<green<blue<white areas of protrusion.
Fig 23.
Morphometric mapping (upper) and sliced segmental extraction (lower) of sample Jomon EN1. It shows no evidence of intentional cranial modification, as displayed by the lack of depressions along sagittal and lambdoidal sutures. Color representations: areas of depression red<yellow<green<blue<white areas of protrusion.