Facial soft tissue thicknesses in craniofacial identification: Data collection protocols and associated measurement errors.

Facial soft tissue thicknesses (FSTT) form a key component of craniofacial identification methods, but as for any data, embedded measurement errors are highly pertinent. These in part dictate the effective resolution of the measurements. As herein reviewed, measurement methods are highly varied in FSTT studies and associated measurement errors have generally not been paid much attention. Less than half (44%) of 95 FSTT studies comment on measurement error and not all of these provide specific quantification. Where informative error measurement protocols are employed (5% of studies), the mean error magnitudes range from 3% to 45% rTEM and are typically in the order of 10-20%. These values demonstrate that FSTT measurement errors are similar in size to (and likely larger than) the magnitudes of many biological effects being chased. As a result, the attribution of small millimeter or submillimeter differences in FSTT to biological variables must be undertaken with caution, especially where they have not been repeated across different studies/samples. To improve the integrity of FSTT studies and the reporting of FSTT measurement errors, we propose the following standard: (1) calculate the technical error of measurement (TEM or rTEM) in any FSTT research work; (2) assess the error embedded in the full data collection procedure; and (3) conduct validation testing of FSTT means proposed for point estimation prior to publication to ensure newly calculated FSTT means provide improvements. In order to facilitate the latter, a freely available R tool TDValidator that uses the C-Table data for validation testing is provided.

Mouth width prediction in craniofacial identification: cadaver tests of four recent methods, including two techniques for edentulous skulls.

An understanding of the structural relationships between the soft tissue anatomy of the face and the hard tissue anatomy of the skull is significant for craniofacial identification methods employed in forensic anthropology and forensic dentistry. Typically, mouth characteristics have been predicted from the teeth but this proves problematic in edentulous skulls. Some clue may, however, be provided by non-dental features. This study investigates the usefulness of the infraorbital and the mental foramen position for determining mouth width and additionally reports on accuracy tests using two other recently proposed methods that depend on the teeth: i) Krogman and Iscan's radiating mouth width prediction guideline; and ii) Stephan and Henneberg's 75% rule. Dissections of nine human cadavers indicate that the most accurate mouth width prediction method is the 75% rule (mean error of -2.4 mm) followed by the distance between the infraorbital foramen (mean error of -3.3 mm). Krogman and Iscan's radiating method, as interpreted by Wilkinson, underestimated mouth width by 7.3mm on average, while the distance between the mental foramen underestimated mouth width by 12.9 mm. These results suggest that the infraorbital foramen can be used as a relatively good predictor of mouth width in edentulous skulls, however, the 75% rule should be given precedence if the dentition is present.

Assessing facial approximation accuracy: how do resemblance ratings of disparate faces compare to recognition tests?

In the past, the accuracy of facial approximations has been assessed by resemblance ratings (i.e., the comparison of a facial approximation directly to a target individual) and recognition tests (e.g., the comparison of a facial approximation to a photo array of faces including foils and a target individual). Recently, several research studies have indicated that recognition tests hold major strengths in contrast to resemblance ratings. However, resemblance ratings remain popularly employed and/or are given weighting when judging facial approximations, thus indicating that no consensus has been reached. This study aims to further investigate the matter by comparing the results of resemblance ratings and recognition tests for two facial approximations which clearly differed in their morphological appearance. One facial approximation was constructed by an experienced practitioner privy to the appearance of the target individual (practitioner had direct access to an antemortem frontal photograph during face construction), while the other facial approximation was constructed by a novice under blind conditions. Both facial approximations, whilst clearly morphologically different, were given similar resemblance scores even though recognition test results produced vastly different results. One facial approximation was correctly recognized almost without exception while the other was not correctly recognized above chance rates. These results suggest that resemblance ratings are insensitive measures of the accuracy of facial approximations and lend further weight to the use of recognition tests in facial approximation assessment.

Recognition by forensic facial approximation: case specific examples and empirical tests.

The skeletal remains of one individual found near Adelaide in 1994, although not known at the time, were the first evidence of what was to be a serial killing reported to have resulted in the highest casualty list to date in Australia (12 victims). Since the usual methods of identification could not be used or were unsuccessful on these remains, facial approximations were produced and advertised over the 4-year period following their discovery, in an attempt to help to identify them. However, no identification was made. In 1999, the remains were reported to be identified by radiographic comparison. Approximately 3 months before this identification was made, another facial approximation was produced by the first author (CNS), but this face was never advertised in the media. Although rarely reported in the literature, this paper provides an example where facial approximation methods were not successful in a forensic scenario. The paper also reports on empirical tests of the facial approximation created by the first author to determine if this facial approximation might have been useful had it been advertised. The results provide further evidence that high resemblance of a facial approximation to the target individual does not indicate recognizability, as the facial approximation was poorly recognized even though it bore good resemblance to the target individual. The usefulness of facial approximation techniques is discussed within the context of this case and more broadly. Methods used to assess the accuracy of facial approximations are also discussed and further evaluated.

Anthropological facial 'reconstruction--recognizing the fallacies, 'unembracing' the errors, and realizing method limits.

Despite being practiced for over the last 200 years, facial approximation methods remain in their infancy as the soft tissue prediction methods employed have not been tested and justified. Scientific testing is the only way forward and much of it is needed. The lack of systematic scientific tests in the past has enabled many misleading notions to become established. Many of these notions appear to have arisen and been sustained as a result of practitioner biases--this is clearly evident even in the name commonly used to describe the method of building faces from skulls, for "facial reconstruction" implies everything the method is not, e.g., technical/scientific, exact, and credible. Although facial approximation methods are useful for forensic investigation (even if they do not generate identifications through true positive recognitions of the faces), the public should beware of the marketing and political ploys employed within the profession. These ploys give rise to some impressive, but unjustifiable claims--but do not just take my word for it; evaluate the evidence for yourself with disregard to the indoctrination waged by the facial "reconstruction" field in general, including that promoted by what I have had to say here. Use your own reason and intellect and see which conclusions you reach.

Position of superciliare in relation to the lateral iris: testing a suggested facial approximation guideline.

It has been suggested in the literature that superciliare is located directly above the most lateral point of the iris and that this association may be of use in facial approximation. However, the relationship between the lateral iris and superciliare has not been tested and its accuracy remains unknown. This study aims to determine the accuracy of this relationship using metric and non-metric analysis. The horizontal distance from superciliare to the lateral iris was measured, using photogrammetric methods, in Australians of European extraction (27 males, 48 females), central/south-east Asian extraction (20 males, 19 females) and individuals from other population groups (7 males, 7 females). Results indicate that superciliare position is best approximated by the lateral iris in females. On average, superciliare fell lateral to the lateral iris by 4.8 mm, S.D. 3.4 mm in males, and 1.2 mm, S.D. 5.4mm in females. In approximately 70-80% of the sample, the superciliare fell between the exocanthion and the pupil center on both sides. It is suggested that the proposed guideline that the lateral iris is equal to superciliare is not very accurate, especially for males. Also the large standard deviations indicate that the position of superciliare is highly variable. The above measures should, on average, give a more accurate prediction of superciliare in contrast to the lateral iris border, and therefore, they should be used in facial approximation. However, the large variation in superciliare position should be acknowledged.

Medicine may be reducing the human capacity to survive.

It appears that limited natural selection is taking place in populations of developed countries, since most individuals survive and have the full opportunity to reproduce. This paper addresses contemporary natural selection in a developed country (Australia) using the biological state index. Although the general context of this paper focuses on Australia it can be expected that most other first-world and/or developed countries follow a similar pattern. The findings of this study, that 98% of individuals survive through their reproductive period and have the full opportunity to reproduce, support predictions that natural selection has limited influence on the evolution of first-world populations. It appears that first-world populations may not be naturally well adapted to their environment but use medical treatments/technology to increase their survival capacity and maintain fitness. This has two apparent consequences. First, the fitness of individuals will decrease, since less favorable genes can accumulate in the population, and secondly, disease processes will remain fit as they adapt to the selective pressures exerted by medicine. If medical treatment becomes ineffective, extensive mortality is expected since fit disease processes will be unleashed on unfit human populations. It appears that a possible answer to these problems may be found in gene therapy.

Building faces from dry skulls: are they recognized above chance rates?

Methods of facial approximation have successfully aided the identification of deceased individuals. Successes may be due to either accurate facial approximation techniques or chance. This study aims to determine if any of 16 facial approximations, built using standard techniques, are sufficiently accurate to produce correct identifications of target individuals above chance. Four skulls were approximated using four commonly used methods of facial approximation. The resulting 16 facial approximations were judged by 37 assessors of varying ages. Assessors attempted to identify the target individual of each facial approximation from a face pool of ten photographed faces. Only one facial approximation resulted in true positive identification rates above chance at statistically significant levels. It is concluded that it is rare for facial approximations to be sufficiently accurate to allow identification of a target individual above chance. Since 403 incorrect identifications were made out of 592 identification scenarios, facial approximation should be considered to be a highly inaccurate and unreliable forensic technique. These results suggest that facial approximations are not very useful in excluding individuals to whom skeletal remains may not belong. Evidence from this experiment supports suggestions by others that facial approximation should be used in forensic science when all other methods of identification have failed and only to provide tentative identification.