Matt Tocheri didn't go to
college immediately after high school. By the time he started his undergraduate
workat Lakehead University in Canadahe had already developed an
interest in anthropology, particularly in the way that scientists were trying
to learn about what it means to be human.
This interest led him after graduation to Arizona State
University (ASU), where he completed his master's degree and is now working on
a Ph.D. in physical anthropology. He explains how he got involved in the
KDI-funded project 3D Knowledge: Acquisition, Representation and Analysis in
a Distributed Environment: "I went to a seminar given by Dr. Anshuman Razdan
[the project's principal investigator], who's the director of the Partnership
for Research in Spatial Modeling (PRISM) here at ASU. [PRISM promotes
interdisciplinary research in 3D data acquisition, visualization and modeling,
and form realization.] I was very excited by what they were doing at PRISM, and
interested in applying some of this technology to forensic science and
anthropology. Dr. Razdan was also interested in that, so he hired me as a
graduate research associate, and I started investigating ways that we could use
3D knowledge to extend how we do research in physical anthropology and related disciplines."
One problem that Tocheri saw in the field of anthropology
was the practice of looking at skeletal features qualitatively, that is,
determining if a particular skeletal feature is there or not there. "But," he says,
"there's always an underlying distribution of variation in any particular feature.
When you examine
things qualitatively, you don't get all the information, you reduce it. So I was really
turned on by the fact that using 3D technology, such as lasers digitizers, CT scans, or
MRIs, we could capture 3D information and be able to analyze it in 3D, without having to
reduce it into 2D such as in a series of linear measurements. This approach can be applied
to any type of object. In my case, the objects are bones."
A visual comparison of the front and side views of the joint surfaces from 3D models of trapezia (the wrist bone directly beneath the thumb). The trapezia belong to four hominid species, Pongo pygmaeus (the orangutan), Gorilla gorilla (the gorilla), Pan troglodytes (the chimpanzee), and Homo sapiens (humans). The light blue surface represents the joint for the thumb while the red represents the joint for the index finger. The yellow and dark blue surfaces represent the joint for two other bones in the wrist.
Tocheri was interested in targeting skeletal features that researchers typically have
described qualitatively. "I wanted to see if I could quantify skeletal variation that would
normally be described in a qualitative sense, in order to get a better understanding of the
distribution of form and structure within a population," he says. Scientists are often forced
to make distinctions, for example, many skeletal features are difficult to quantify such as
the curvature and shape of a bone or joint surface. These features must often be described
qualitatively, for instance, as being less or more curved. The 3D approach allows a researcher
to use the software designed by the team at ASU as part of the KDI grant to interact with the
data and maintain the actual 3D variation. "Instead of having to reduce to a particular feature
to a category such as less curved versus more curved," says Tocheri, "we can objectively
quantify the curvature and other aspects and give it a continuous number (so that each feature
has its own value). So instead of categorizing features qualitatively, we're uncovering the
underlying quantitative continuous distribution of each feature."
Tocheri became increasingly interested in refining ways of determining how old someone was when
he or she died. Working with Dr. Razdan and other members of the PRISM team, Tocheri has been
modeling bone surfaces that are traditionally used to determine the age-at-death of an individual
from their skeleton. These bone surfaces are typically analyzed using photographs or casts.
Moving the analysis into 3D provides many areas for refinement of the techniques, potentially
leading to more positive identifications of unknown individuals.
This work at PRISM led him to Dr. Mary Marzke, an anthropologist at ASU who was also involved in
the KDI project. Dr. Marzke studies functional morphology, which tries to understand how the skeleton
functions and how those functions relate to behavior. One of her main interests is the evolution and
functional morphology of the human hand. She examines fossil records to find when the skeletal features
that correspond to some of the ways we use our handsespecially tool usingfirst appeared.
Tocheri began working with Dr. Marzke. "We are studying the bones of the wrist and the hand (of humans and of
other species) by laser scanning them so that we have 3D computer models of the bones. These bones are very
complex, especially the wrist bones, and traditionally it's been difficult for researchers to study and
measure them objectively and consistently. With the KDI grant, we've developed ways to extract 3D information
from these bones and come up with some really interesting and meaningful similarities and differences in the
structure of our wrist in comparison to other primate species [see figure]. We try to relate those morphologies
to the functional complexes we have that allow us to use the hand for sophisticated tool use."
This has become the project for Tocheri's Ph.D. "When I came to ASU, I never thought I would try to work on
hands and wriststhe complexity was too great. But thanks to the KDI grant, this is now my field." Today, Matt
Tocheri is a graduate research associate at PRISM. Tocheri's research has applications in both the present and
the past. If a body is found today that's decomposed beyond the point of identification, a forensic scientist
must examine the skeleton and come up with the person's vital statisticshow old they were at their death,
whether they were male or female, etc. In order to do this, research such as Tocheriís, improves the ability
to make such assessments. These same techniques allow researchers to study and learn more from prehistoric
skeletons and fossils. Tocheri's research also has applications in the delicate field of hand surgery. Today,
a number of surgical procedures rely on information provided by the work of Dr. Marzke, Matt Tocheri, and others
who study the hand.
To learn more about Matt Tocheri's work, visit the PRISM Web
site at: http://prism.asu.edu/
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