Here’s a post for International Women’s Day, but I was going to put it up anyway before I found out this morning that it was IWD.

The media is buzzing with the results of a new analysis by Richard L. Jantz of bones found on Nikumaroro Island in 1940, and the possibility—”the likelihood”, says Jantz—that they belonged to Amelia Earhart, who, he argues, died on that island after crash-landing in 1937 during her around-the-world flight with her navigator, Fred Noonan. Jantz is an emeritus professor in the Department of Anthropology at the University of Tennessee in Knoxville, and has expertise in identifying the origin of human bones. His paper, just published in Forensic Anthropology (reference at bottom), is free online, and the pdf is here.

I won’t recount the story of Earhart, or the many theories of what happened to her (I’ve written about this several times before); you can see the long Wikipedia entry for that. Her disappearance got lots of attention—more so than other vanished aviators—because she was a pioneering woman aviator, because she was already famous for breaking aviation records, and because she was popular with the American public, being genial and outgoing to reporters. (Her personal life was a bit of a mess, but we won’t get into that.) She disappeared on the final leg of her journey home, having taken off from New Guinea and heading to small Howland Island, from where she was going to fly to Hawaii and then to California. Despite a radio ship being stationed near Howland, Earhart couldn’t hear their transmission, though they could receive hers (she reported being low on fuel and flying a north-south line). She, Noonan, and the plane disappeared, and the rest is mystery.

In 1940 several bones, including a skull, humerus, radius, tibia, fibula, and two femurs, were found on Nikumaroro Island, a few hundred miles south of Earhart’s destination. Along with the bones were part of a shoe thought to be a woman’s shoe (see below), a sextant box for carrying a 1918-made instrument, and a Benedictine bottle. Here’s Nikumaroro relative to Howland; it’s a classic Pacific atoll, and the proposed site for her emergency landing is given in the second map (both from Betchart Expeditions):

The bones were taken to Fiji where they were measured by Dr. D. W. Hoodless, principal of the island’s Central Medical School. They’ve since disappeared, which is a great pity since DNA from those bones might have allowed a positive identification. (Earhart had no children, but perhaps there are relatives of her still alive.)

All we have are Hoodless’s seven measurements, four of the skull as well as the length of the humerus, radius and tibia. From these measurements, Hoodless concluded that the bones belonged to “a middle-aged stocky male about 5’5.5″ in height.” A reanalysis in 1998 took issue with that, arguing that the bones belonged to a female of European ancestry between 5’6″ and 5’8″ tall. The latter conclusions comport with Earhart, who was probably between 5’7″ and 5’8″: tall for a woman in those days. Here’s Earhart’s driver’s license; her pilot’s license adds an inch to the height recorded here.

To make a long story short, Jantz finds severe flaws in Hoodless’s methodology and conclusions (he screwed up both the sex and stature of the individual), and reanalyzes both the bone data and Earhart’s height and build from old photographs as well as a pair of her trousers that reside at a museum at Purdue University.

Using bones from Pacific Islanders, male and female, as well as from Europeans, Jantz finds Earhart fitting closer to European males than to the Islanders, but also closer to males than females. But she was tall: as tall as the average male, and these conclusions are based on bone length. He then estimates the robustness of Earhart’s build from both the bone data and photos taken of Earhart when she was alive; Jantz did this because Earhart was assumed to be very “gracile” (slender), which did not fit the bone measurements.

It’s amusing to see Jantz engaged in a bit of Earhart fat-shaming, saying she had fat ankles, “piano legs,” and was stockier than everyone assumed.  This is what he says:

It is now possible to address the question of what Earhart’s body build actually was, since it bears on what Hoodless may have seen before him. Cross and Wright (2015) characterize Earhart as tall, slender, and gracile, citing numerous photos of her to support this assessment. However, the few photos showing Earhart’s bare arms or legs (Figure 5) show a woman with a healthy amount of body fat. The photos in Figure 5are inconsistent with a weight of 118 pounds and a BMI of 17.9, which according to contemporary standards is in the underweight or undernourished category. If her height is actually 5’7″, that brings her BMI to 18.5, just to the lower border of healthy weight. But even that is inconsistent with the photos in Figure 5.

It is evident from Figure 5 that Earhart’s calves and ankles cannot be described as slender. In the 1933 photo she is standing next to a woman somewhat taller, but with rather more slender ankles. One of Earhart’s biographers, Susan Butler (1997), recounts that because of her thick ankles, her legs could be described as “piano legs.” Thick ankles are not normally due to an undesirable distribution of fat; the subcutaneous fat layer is normally thin, the ankle configuration owing to underlying bone and muscle (Weniger et al. 2004). Ankle circumference is often used as a measure of frame size (Callaway et al. 1991). Calf and ankle circumference are strongly correlated with weight (Cheverud et al. 1990a), the former reflecting mainly muscle and fat, the latter mainly bone.

She still looks slender to me, even if her ankles weren’t so slim; here is Figure 5.

He concludes that Earhart had a BMI (body mass index) closer to 19 than to 17.1, and probably weighed closer to 130 pounds than 118 pounds, so her skeleton was not as gracile as everyone thinks. (Judging this is, of course, above my pay grade.) With a 27.3-inch waist, about 4 inches less than U.S. military women today, I consider her slim, regardless of her ankles!

Jantz further estimates the lengths of Earhart’s humerus (upper arm bone) and radius (one of the two lower arm bones) from a picture taken shortly before her flight, using markers on the photo (see below) and the known size of the gas can in her hand. He estimates her humerus at 321.1 mm and radius of 243.7 mm, compared to 325 and 245 for the Nikumaroro bones.

The tibia length taken from Earhart’s trousers gives an estimate of 371.7 mm, compared to 372.4 estimated from her height as 67 inches. Those comport well with the 372 mm measurement of the found bone.  Jantz then uses just bone lengths to compared Earhart’s combined data to those of a sample of 2776 individuals from a collection of what I take to be “Euro-American” postcranial measurements (the data are NOT well described; they don’t include Polynesian or Pacific bones, but those would in all likelihood have been shorter). This plot shows the “Mahalanobis distance” of bones from the collection to the bones collected on Nikumaroro. Males are on the top, females on the bottom, and the line shows where Earhart’s data, taken from photos and pants measurements, fits. The closer the estimated data to the found bones, the more similar they are, and the closer to the left-hand size (“zero distance”) on the plots:

As you see, for both sexes Earhart’s estimated data is much closer to a “match” with the found bones than are most individuals in Jantz’s database. He estimates that 98.77% of individuals from his female sample are farther than Earhart’s estimates from the zero point. That means that there’s a very good match between Earhart’s estimated measurements and the actual bones, and a much closer match than that of a random female from the sampled population.

Well, as I said, this is all above my pay grade. All I can say is that yes, the bone lengths seem to match Earhart’s, but so do many people (1.3% of all human females), so this is not a match that would stand up in court. Nevertheless, both Jantz and the press consider this a pretty positive identification of Earhart’s bones, and a solution to the mystery of her disappearance. As Jantz says at the end of the paper:

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.

. . . 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 [11 men], 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.

This is a long way from convincing me, for we can’t tell whether the bones are male or female, and Earhart’s measurements were estimated from photos and have fairly big error bars around them. What a pity those bones aren’t around, as Svante Paabo or one of his ilk could use them to test their DNA—if any remained—for a match to living relatives. So it’s suggestive, but hardly dispositive.

There was a Europeans woman’s shoe and a compass, box, though, and that adds some weight to the evidence. But to me, the mystery is a long way from being solved. The media is being way too credulous, although some places have interviewed experts who find Jantz’s analysis wanting.

Oh, hell, I’ll add the shoe information from a paper by Karen Burns et al.:

h/t: Roger Latour

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Jantz, R. L. 2018. Amelia Earhart and the Nikumaroro bones: A 1941 analysis versus modern quantitative techniques. Forensic Anthropology 1(2):1-16.