Post by Admin on Apr 1, 2018 18:52:57 GMT
Discussion
Let us suppose, for the sake of argument, that the Nikumaroro bones are the remains of Amelia Earhart. In light of the above, we can now reconsider what Hoodless might have seen before him and how he might have assessed what he saw. The skeleton before him would have had bone lengths clearly in the male range. From what we see of Earhart’s lower leg morphology, it is quite possible, even likely, that the tibia was relatively robust. As a tall and narrow-bodied female, the “set” of the femora could well have appeared male to Hoodless. It is apparent from the many photos of Earhart, and from her waist circumference, that her hips were narrow for a female. This, in combination with her height, does not require a femur angle one might expect of a female. It may also suggest an ambiguous half subpubic angle that could easily have been called male by an inexperienced eye, or even an experienced one, particularly if taphonomic processes had modified the morphology.
If Hoodless’s analysis, particularly his sex estimate, can be set aside, it becomes possible to focus attention on the central question of whether the Nikumaroro bones may have been the remains of Amelia Earhart. There is no credible evidence that would support excluding them. On the contrary, there are good reasons for including them. The bones are consistent with Earhart in all respects we know or can reasonably infer. Her height is entirely consistent with the bones. The skull measurements are at least suggestive of female. But most convincing is the similarity of the bone lengths to the reconstructed lengths of Earhart’s bones. Likelihood ratios of 84–154 would not qualify as a positive identification by the criteria of modern forensic practice, where likelihood ratios are often millions or more. They do qualify as what is often called the preponderance of the evidence, that is, it is more likely than not the Nikumaroro bones were (or are, if they still exist) those of Amelia Earhart. If the bones do not belong to Amelia Earhart, then they are from someone very similar to her. And, as we have seen, a random individual has a very low probability of possessing that degree of similarity.
Ideally in forensic practice a posterior probability that remains belong to a victim can be obtained. Likelihood ratios can be converted to posterior odds by multiplying by the prior odds. For example, if we think the prior odds of Amelia Earhart having been on Nikumaroro Island are 10:1, then the likelihood ratios given above become 840–1,540, and the posterior probability is 0.999 in both cases. The prior odds or prior probability pertain to information available before skeletal evidence is considered. It is often impossible to assign specific numbers to the prior probability, because it depends on how the non-osteological evidence is evaluated, and different people will usually evaluate it differently. In jury trials, experts are often advised to testify only to the likelihood ratio developed from the biological evidence. The jury then supplies its own prior odds based on the entire context (e.g., Steadman et al. 2006).
In the present instance, readers can supply their own interpretation of the prior evidence, summarized by King (2012). Given the multiple lines of non-osteological evidence, it seems difficult to conclude that Earhart had zero probability of being on Nikumaroro Island. From a forensic perspective the most parsimonious scenario is that the bones are those of Amelia Earhart. She was known to have been in the area of Nikumaroro Island, she went missing, and human remains were discovered which are entirely consistent with her and inconsistent with most other people. Furthermore, it is impossible to test any other hypothesis, because except for the victims of the Norwich City wreck, about whom we have no data, no other specific missing persons have been reported. It is not enough merely to say that the remains are most likely those of a stocky male without specifying who this stocky male might have been. This presents us with an untestable hypothesis, not to mention uncritically setting aside the prior information of Earhart’s presence. The fact remains that if the bones are those of a stocky male, he would have had bone lengths very similar to Amelia Earhart’s, which is a low-probability event. Until definitive evidence is presented that the remains are not those of Amelia Earhart, the most convincing argument is that they are hers.
Forensic Anthropology Vol. 1, No. 2: 1–16
DOI 10.5744/fa.2018.0009
Let us suppose, for the sake of argument, that the Nikumaroro bones are the remains of Amelia Earhart. In light of the above, we can now reconsider what Hoodless might have seen before him and how he might have assessed what he saw. The skeleton before him would have had bone lengths clearly in the male range. From what we see of Earhart’s lower leg morphology, it is quite possible, even likely, that the tibia was relatively robust. As a tall and narrow-bodied female, the “set” of the femora could well have appeared male to Hoodless. It is apparent from the many photos of Earhart, and from her waist circumference, that her hips were narrow for a female. This, in combination with her height, does not require a femur angle one might expect of a female. It may also suggest an ambiguous half subpubic angle that could easily have been called male by an inexperienced eye, or even an experienced one, particularly if taphonomic processes had modified the morphology.
If Hoodless’s analysis, particularly his sex estimate, can be set aside, it becomes possible to focus attention on the central question of whether the Nikumaroro bones may have been the remains of Amelia Earhart. There is no credible evidence that would support excluding them. On the contrary, there are good reasons for including them. The bones are consistent with Earhart in all respects we know or can reasonably infer. Her height is entirely consistent with the bones. The skull measurements are at least suggestive of female. But most convincing is the similarity of the bone lengths to the reconstructed lengths of Earhart’s bones. Likelihood ratios of 84–154 would not qualify as a positive identification by the criteria of modern forensic practice, where likelihood ratios are often millions or more. They do qualify as what is often called the preponderance of the evidence, that is, it is more likely than not the Nikumaroro bones were (or are, if they still exist) those of Amelia Earhart. If the bones do not belong to Amelia Earhart, then they are from someone very similar to her. And, as we have seen, a random individual has a very low probability of possessing that degree of similarity.
Ideally in forensic practice a posterior probability that remains belong to a victim can be obtained. Likelihood ratios can be converted to posterior odds by multiplying by the prior odds. For example, if we think the prior odds of Amelia Earhart having been on Nikumaroro Island are 10:1, then the likelihood ratios given above become 840–1,540, and the posterior probability is 0.999 in both cases. The prior odds or prior probability pertain to information available before skeletal evidence is considered. It is often impossible to assign specific numbers to the prior probability, because it depends on how the non-osteological evidence is evaluated, and different people will usually evaluate it differently. In jury trials, experts are often advised to testify only to the likelihood ratio developed from the biological evidence. The jury then supplies its own prior odds based on the entire context (e.g., Steadman et al. 2006).
In the present instance, readers can supply their own interpretation of the prior evidence, summarized by King (2012). Given the multiple lines of non-osteological evidence, it seems difficult to conclude that Earhart had zero probability of being on Nikumaroro Island. From a forensic perspective the most parsimonious scenario is that the bones are those of Amelia Earhart. She was known to have been in the area of Nikumaroro Island, she went missing, and human remains were discovered which are entirely consistent with her and inconsistent with most other people. Furthermore, it is impossible to test any other hypothesis, because except for the victims of the Norwich City wreck, about whom we have no data, no other specific missing persons have been reported. It is not enough merely to say that the remains are most likely those of a stocky male without specifying who this stocky male might have been. This presents us with an untestable hypothesis, not to mention uncritically setting aside the prior information of Earhart’s presence. The fact remains that if the bones are those of a stocky male, he would have had bone lengths very similar to Amelia Earhart’s, which is a low-probability event. Until definitive evidence is presented that the remains are not those of Amelia Earhart, the most convincing argument is that they are hers.
Forensic Anthropology Vol. 1, No. 2: 1–16
DOI 10.5744/fa.2018.0009