Tag Archive: mtDNA


Amelia Earhart and her navigator, Fred Noonan, disappeared in 1937 during her attempt to become the first female to fly around the world. Flying near Howland Island in the Pacific, communication with her plane was lost. Finally, after an intense search by the U.S. government, she and Noonan were officially pronounced dead  on January 5, 1939. Since then, there has been speculation about whether they actually died in a crash at sea, or survived for some time on a deserted island.

Amelia Earhart disappeared in 1937. Image from Discover Magazine.

Two years ago, the International Group for Historic Aircraft Recovery found bone fragments on Nikumaroro Island that may be part of Earhart’s finger. However, a dead sea turtle was found nearby, raising the reasonable possibility that the bone fragments also belong to the turtle. Apparently the bone fragments are too small to identify just by looking at them, so researchers want to extract DNA from the bone to compare to Earhart’s. How do we get DNA from her, you may ask? From National Geographic:

The new Earhart DNA project will be headed by Dongya Yang, a genetic archaeologist at Simon Fraser University in Burnaby, Canada. Yang will examine Earhart’s letters and attempt to extract DNA from mouth-lining cells that would have been in the saliva she used to seal the envelopes. Mining a trove of more than 400 correspondences between Earhart and various people, the researchers have chosen four letters to family—deemed the most likely to have been written and sealed by Earhart herself—for analysis.

Yang is aiming to gather two kinds of DNA from the letters: mitochondrial DNA, which children inherit from their mothers only, and nuclear DNA, which contains the bulk of a person’s genetic information and is housed in each human cell’s nucleus. If both DNA types can be obtained, the team says it can create a genetic profile of Earhart that is complete enough to positively identify any potential remains.

If the project proceeds smoothly, Yang said, the team could have a genetic profile for Earhart in “a couple months.”

Let’s see what happens…

Based on archaeology, linguistics, and, most recently, genetics, it is traditionally thought that Polynesia was inhabited by mariners originating in Taiwan or south China beginning about 3,500 years ago (in fact, our departmental reading, Relethford’s “Reflections of Our Past,” has an interesting chapter on this issue).

Polynesia is made up of hundreds of islands. Figure from acmecompany.com

A recently published study modifies this story somewhat. This study looked at the largest mtDNA (which is only passed through the maternal line) sample to date in order to determine which populations were most similar to modern Polynesians. From an interview with Martin Richards, one of the members of the research team, in the ScienceDaily summary:

“Most previous studies looked at a small piece of mtDNA, but for this research we studied 157 complete mitochondrial genomes in addition to smaller samples from over 4,750 people from across Southeast Asia and Polynesia. We also reworked our dating techniques to significantly reduce the margin of error. This means we can be confident that the Polynesian population — at least on the female side — came from people who arrived in the Bismarck Archipelago of Papua New Guinea thousands of years before the supposed migration from Taiwan took place.”

 What is especially interesting here is that the linguistic and archaeological evidence still strongly suggest some sort of connection with Taiwan. For one, modern Polynesian languages are thought to belong to the Austronesian language family, which is a group of languages spoken from Madagascar to Easter Island, but differ from the native languages of Australia and New Guinea. Archaeologists maintain that the earliest Polynesian pottery (called the “Lapita Culture”) shares many similarities to earlier pottery found on Taiwan and in south China. So, how do we reconcile these findings with the genetics? Again, Dr. Richards:

“Although our results throw out the likelihood of any maternal ancestry in Taiwan for the Polynesians, they don’t preclude the possibility of a Taiwanese linguistic or cultural influence on the Bismarck Archipelago at that time,” explains Professor Richards. “In fact, some minor mitochondrial lineages back up this idea. It seems likely there was a ‘voyaging corridor’ between the islands of Southeast Asia and the Bismarck Archipelago carrying maritime traders who brought their language and artefacts and perhaps helped to create the impetus for the migration into the Pacific.

“Our study of the mtDNA evidence shows the interactions between the islands of Southeast Asia and the Pacific was far more complex than previous accounts tended to suggest and it paves the way for new theories of the spread of Austronesian languages.”

This implies that later populations were moving through the area with their language and culture, but they were not necessarily bringing their genes (i.e., interbreeding), at least on the female side.

References

Soares, P., et al. Ancient Voyaging and Polynesian Origins. American Journal of Human Genetics 88: 239-247.