This analysis examined cranial epigenetic and morphological nonmetric traits in 756 subadults (fetal to <20 years), in European, African, and Asian samples. The goals of this research were to assess: the age and manner in which nonmetric traits develop and if variation between geographic groupings is present in subadults; the role of the adolescent growth spurt in trait expression; the feasibility of utilizing subadult crania in biological distance studies and ancestry assessment.
A number of epigenetic and morphological traits show a primarily genetic versus developmental basis, suggested by the fact that there was no difference in trait frequencies between the fetal/0-3 and 15-20 year age categories. Eighty-five percent of epigenetic traits appear before 3 years; 54% were age stable by 3 years, and 75% were stable before age ten. Geographic cranial variation is present at an early age as demonstrated by the appearance of 58% of morphological traits before age 3, and 90% by age 10. Ten and a half percent of morphological traits are age stable before 3 years of age, 48% by age 10.
Traits statistically significant between pre-pubertal and pubertal and/or pubertal and post pubertal individuals are hyperostotic, functional, and in some cases, sex dependent. Few epigenetic (1.3%) and morphological traits (7.9%) were found to be sex dependent, possibly because sexually dimorphism may not be fully expressed in individuals in the 15-20 year age category. Features that indicate ancestry develop before puberty, and do not require the onset of puberty and sexual dimorphism to be fully formed.
Three-quarters of epigenetic traits were age stable and showed trait frequencies similar to adults before 10 years of age, suggesting subadults could be included in biodistance studies using these traits. Twenty-four morphological traits were statistically significant between geographic groups and show promise for future use in the forensic analysis of ancestry assessment in children.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/43402 |
| Date | 16 December 2013 |
| Creators | Wood, Carolan |
| Contributors | Rogers, Tracy |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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