Biology Reference
In-Depth Information
forensic case that was positively identified as a Laotian male. The reader is encouraged to
utilize the help file and the tutorials within to further explore this example.
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Of course,
another approach is nonmetric (morphoscopic) data, which have been used to verify metric
analyses or to refute their outcome. In the following section, we explore morphoscopic traits
and their use in the assessment of ancestry.
Nonmetric Methods
Nonmetric traits have a long history in anthropology, particularly as they relate to ancestry
assessment. However, there are two distinct types of cranial nonmetric traits: epigenetic vari-
ants and morphoscopic traits. While the focus of this chapter is on the latter, one should
understand both types. Traditional cranial nonmetric, or discrete, traits (“epigenetic vari-
ants” following Hauser and DeStefano, 1989) are defined following
Buikstra and Ubelaker
(1994)
as “dichotomous, discontinuous, epigenetic traits
d
non-pathological variations of skeletal
tissues that can be better classified as present or absent (or as a point on a morphological
gradient, e.g. small to large) rather than quantified by a measurement.”
There are five major categories of epigenetic variants in the cranium: (1) extrasutural bone
(e.g., Inca bone); (2) proliferative ossifications (e.g., pterygo-alar bridging); (3) ossification
failure (e.g., septal aperture); (4) suture variation (e.g., metopic suture); and (5) foramina vari-
ation (e.g., zygomatico-facial foramen number) (
Buikstra and Ubelaker, 1994
). As discussed
earlier, the roles played by the genome and the environment in the inheritance of cranial
nonmetric traits (or any phenotypic traits) are poorly understood. However, these traits
are routinely used in biological distance studies as a measure of relatedness within and
between populations (i.e.,
Sjøvold 1977, 1984, 1986
) and as a proxy for identifying familial
relationships within cemeteries (
Pilloud, 2009
). In a forensic context, the traits used to assess
ancestry are not necessarily the same characters as epigenetic variants, because of the unique
history of morphoscopic traits in forensic anthropology (
Hefner, 2009
).
Morphoscopic Traits
Ousley and Hefner (2005)
first used the term “macromorphoscopic” to describe the cranial
nonmetric traits used in forensic anthropological research. They considered macromorpho-
scopic traits to be quasicontinuous variables of the cranium that can be reflected as soft-tissue
differences in the living (cf.,
Brues' [1958]
: second class of traits “due to the contour of bone in
areas where it closely follows the surface
apparent in both skeleton and living”). Later,
Hefner (2009) simplified the term to morphoscopic traits but maintained the original character-
ization of the variables. These traits fall into one of five classes: (1) assessing bone shape (e.g.,
nasal bone structure); (2) bony feature morphology (e.g., inferior nasal aperture
morphology); (3) suture shape (e.g., zygomaticomaxillary suture); (4) presence/absence of
data (e.g., post-bregmatic depression); and (5) feature prominence/protrusion (e.g., anterior
nasal spine) (
Hefner, 2009
).
.
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FORDISC 3.0 is available from the Forensic Anthropology Center at the University of Tennessee
<
>
; additionally, any forensic anthropology laboratory in the U.S. and Canada will
have a copy.
