Amelia Earhart, the first woman to fly solo across the Atlantic Ocean, disappeared over the Pacific Ocean in 1937 during an attempt to circumnavigate the globe. Since then, attempts to locate her, her co-pilot Fred Noonan and their plane have been too numerous to count.
Now, a group a researchers from the International Group for Historic Aircraft Recovery (TIGHAR) claim that a skeleton discovered in 1940 could be the famed aviator's remains.
A new look at old bones
Earhart and Noonan are believed to have disappeared somewhere near Howland Island, a small island in the central Pacific, but pinpointing an exact location has always been difficult. However, recent interest has focused on Gardner Island — also called Nikumaroro — which is located 400 miles south of Howland.
In 1940, skeletal remains were discovered on Gardner Island, but the doctor at the time declared the bones to be male, eliminating the possibility that the skeleton was Earhart. TIGHAR discovered these doctors' files in 1998, and researchers from the group declared that the remains were "consistent with a female of Earhart's height and ethnic origin."
Jump to 2016. Anthropologist Richard Jantz was preparing an updated evaluation to the 1998 report when he noticed something slightly unusual about the skeleton: Its forearms were larger than average. The skeleton's humerus, or upper arm bone, was 32.4 centimeters long, while the radius, or lower arm bone was 24.5 centimeters, with a ratio of humerus to radius of 0.756. The forearm of women in the 1930s had, on average, a radius to humerus ratio of 0.73, meaning the skeleton's forearms were larger than average.
Jantz wondered if Earhart's forearms were larger than a normal woman's at the time. However, without measurements of Earhart's forearms, there'd be no way to know if the arms matched.
Jantz and TIGHAR enlisted forensic imaging specialist Jeff Glickman to help sort out this mystery. Using a photo of Earhart with her forearms visible, Glickman calculated the ratio between the bones in her lower and upper arm.
In Glickman's final report, he declared the radius-to-humerus ratio to be 0.76, roughly the same ratio as the remains found in 1940. Glickman makes allowances for clothing and living tissue in the photo as obscuring where bones might potentially be, but he used the point of her shoulder, the crease of her elbow and the indent of her wrist as landmarks to measure as as well as he could.
TIGHAR cautions that the match of the radius-to-humerus ratio doesn't necessarily mean it's Earhart, but that the findings are "a significant new data point that tips the scales further in that direction."
However, Jantz strongly supports the idea that the bones are in fact Earhart's because of an analysis that she was more similar to the bones than 99 percent of individuals from a sample.
More from TIGHAR
This isn't the first time that TIGHAR has explored what happened to Earhart.
In May 2013, an anomaly on sonar images from the floor of the Pacific Ocean was discovered, and researchers from TIGHAR said it could be the wreckage of Amelia Earhart's airplane.
In 2012, TIGHAR conducted two expeditions to Gardner Island and used underwater robots and other technology to explore the area, but they did not produce any conclusive evidence at the time, in part because technical issues and weather conditions thwarted some of their efforts.
But while reviewing the data from the expedition, TIGHAR researchers noticed something they had missed: "a sonar image...that could be the wreckage of Amelia Earhart's Lockheed Electra. It looks unlike anything else in the sonar data, it's the right size, it's the right shape, and it's in the right place," the organization's website proclaims.
The object is about 22 feet long in waters about 600 feet below the surface. TIGHAR was actively looking just a few hundred feet from where the anomaly lies, so they did not see it until reviewing the data this March. It was actually spotted by someone online, as recounted on the TIGHAR website:
"It wasn't until March 7, 2013, that Richard Conroy, a member of TIGHAR's on-line Amelia Earhart Search Forum, spotted the anomaly in a sonar map that was included in the Niku VII report in TIGHAR Tracks. Richie has no training in interpreting sonar images but that was probably his biggest advantage. Once you know what to look for, the anomaly is painfully obvious. It gives the impression of being an object that struck the slope at the base of the second cliff at a depth of 187 meters (613 feet), then skidded in a southerly direction for about 40 meters (131 feet) before coming to rest."
A follow-up look at the sonar data conducted by Oceanic Imaging Consultants, Inc., in June 2013 revealed that the object's length could be as little as 34 feet long or as much as 39.5 feet. As the TIGHAR report explained, "[the object] could be the length of a Lockheed Electra with a slightly crushed nose, or the length of an intact 11.76 meters (38.5 feet) Lockheed Electra fuselage; or it could be about one foot too long to be an Electra fuselage. The Holy Grail or close-but-no-cigar?"
Between possible plane remains in the ocean and skeletons with potentially matching arm sizes, the mystery of Amelia Earhart's disappearance may be closer to an answer.
This story was originally published in May 2013 and has been updated with new information.