Before ForDisc, many anthropologists based their studies off of museum skeletal collections such as the Hamann-Todd collection that is housed at Case Western Reserve in Cleveland, Ohio, and the Terry collection housed at the Smithsonian Institution in Washington, DC. These museum collections house skeletal remains that were amassed from 50 to 100 years ago. Due to the age of these collections, their use in a medico-legal context did not produce accurate determination of the biological profile. ForDisc was forensic anthropologists solution to this problem, and allowed for classification when some measurements are not available.
Contents
Software
ForDisc, an interactive discriminant functions program created by Stephen Ousley and Richard Jantz, is widely used by forensic anthropologists to assist in the creation of a decedent's biological profile when only parts of the cranium are available. The use of discriminant function analysis in this program allows the researcher to sort individuals into specific groups that are defined by certain criteria. In this program discriminate function analysis "analyzes specific groups with known membership in discrete categories such as ancestry, language, sex, tribe or ancestry, and provides a basis for the classification of new individuals with unknown group membership." The program compares potential profiles to data contained in a database of skeletal measurements of modern humans.
Using ForDisc, a decedent’s biological profile can be created based on measurements from various areas of bones, along with information about the person's age, height, race, and illnesses. For ancestry ForDisc uses standard anthropometric measurements including maximum length, maximum breadth, bi-zygomatic breadth, orbital breadth and height, maximum alveolar breadth and width, minimum frontal breadth, basion-bregma, basion-prosthion, cranial base length, bi-auricular breadth, upper facial height and breadth, foramen magnum breadth and length, frontal chord, parietal chord, occipital chord, nasal height and breadth, bi-orbital breadth, inter orbital breadth, and mastoid length.
Data Bases
The data behind this software largely originated from the Forensic Data Bank, which is contributed to by the University of Tennessee and other contributing institutions. The Forensic Data Bank was created in 1986, through the use of a National Institute of Justice grant, and has gathered over 3400 cases.The Forensic Data Bank is a currently ongoing effort to record information about modern populations, primarily from forensic cases.
ForDisc's creators have also integrated W. W. Howells worldwide cranial data in to the program, for the use of archaeological remains. Howell's craniometric data set consist of 2500 crania from 28 different populations around the world dating to the later Holocene, in which around 82 cranial measurements were obtained.
Uses
This software is able to estimate the sex, ancestry, and stature from a skeleton of unknown identity. This software also can be used for international hearings of war crime and investigations of human rights. This method is also used by the FBI, in different types of criminal cases.
Although this program was created for forensic anthropology use, many physical anthropologists are still using the program to determine the biological profile of skeletal remains that are considered archaeological in origin, but the use of this program on archaeological remains has produced misclassifications in the past. The use of William W. Howell’s craniometric data set, which is published online, has made ForDisc 2.0 more appealing to many physical anthropologists concerned with archaeological remains.
Updates
This program is continually updated. New and updated versions are created and added as more knowledge is acquired. The new features of ForDisc 2.0 are improved pictorial guide to measurements, and improved file management and printer control; larger number of variables, including post cranial variables; larger numbers of groups, including Howells' worldwide cranial data. The newest version, ForDisc 3.0 is an interactive forensic software that runs under the Windows system.
Criticism
According to the authors of the program, there are limitations that should be taken into account when using this program. Some of these limitations include the fact that ForDisc will classify any unknown into the ‘closest’ group, this means that even if an individuals ethnic group or race is not represented in the database, the program will classify it to the ‘closest’ group. Another limitation involves classification using hybrid individuals and groups. The authors state that genetic exchange between groups can cause misclassifications due to gene overlap that can consist of two ancestral populations. Another limitation deal with the classification of individuals under the age of 18, this is due to the nature of physical anthropologists ability to assess age in subadults. However, the authors state that there are differences between subadults in different groups, but these differences tend to not correspond to differences seen in adults. Another limitation that the authors believe researchers should take into account is the fact that this program is based on measurements that are effected by "disease, disuse, treatment, or trauma." The measurement of effected bone(s) may produce values that are inaccurate, and therefore he classification will not reflect the correct population affinity.
The last limitation deals with archaeological populations. This limitation is due to the fact that most of the measurements in the data set that the classifications are based on in the program are from remains that are from the 20th century, and should not be used for classification of archaeological remains. This is because documented population differences and secular changes that have occurred throughout history. However, the inclusion of W. W. Howells craniometric data set has allowed researchers to classify archaeological remains due to the fact that much of the data set comes from individuals from the 19th century.
A 2009 study found that FORDISC 3.0 "is only likely to be useful when an unidentified specimen is more or less complete and belongs to one of the populations represented in its reference samples", and even in such "favorable circumstances it can be expected to classify no more than 1 per cent of specimens with confidence."
In 2012 research was presented at the 81st Annual Meeting of the American Association of Physical Anthropologists, which concluded ForDisc ancestry determination was not always consistent, and the programs' recommended acceptance criteria did not separate correct and incorrect determinations. The authors concluded that the program does not perform to expectations and should be used with caution.