Tracing generations

 

Child's hand and an elderly person's handRebecca Fredericks learns how developments in DNA research are allowing UTS researchers to track ancestral lineage back hundreds of thousands of years.

Countless hours are spent by novice researchers thumbing through books and trawling the world wide web in an effort to trace their family trees. But new DNA research being conducted at UTS has broken all boundaries of genealogy, enabling scientists to trace ancestral lines back hundreds of thousands of years.

“I recently tested a swab where the person had assured me they were of French ancestry. They had fair skin and blue eyes, so it was interesting to discover that their mitochondrial DNA quite clearly stated that they had descended from Africa,” says UTS PhD student Charmain Castel.

This type of ancestral DNA tracing first hit popular consciousness with a book by Professor Bryan Sykes entitled The Seven Daughters of Eve. It traced the ancestral lineage of Europeans back thousands of years to seven different ‘mothers’.

Associate Professor Anita Piper from the UTS Faculty of Science explains: “Mitochondrial DNA is passed down from a mother to her children. It does not mix with DNA contributed from the father and so it basically remains unchanged...

“As people moved to different geographic locations, the mutations became localised in certain regions. This is how we can determine what area specific DNA originated in and the geographic journey it has taken since.”

Although the research conducted by Sykes was groundbreaking, it is just the tip of the iceberg. There are many geographic locations whose ancestry is yet to be traced, and Castel intends to build upon this research.

“I discovered several geological groups that had quite a few similarities, especially in Asia,” says Castel. “This could mean some interesting developments in terms of population movement.”

As part of her PhD research, Castel has amassed a database of about 400 swabs from UTS students who have volunteered to be part of the project. “We get the students to fill in an ancestry form which provides information on nationality, parent and grandparent nationalities. We then test the mitochondrial DNA in that swab to trace the person’s ancestry,” says Castel.

This can lead to some interesting findings, including the student who believed they had French ancestry. Castel is also working on the Y chromosome. “This will enable us to trace both parents, and compare the results.”

Testing the Y chromosome has also led to some interesting discoveries, such as the fact that approximately 16 million men – eight per cent of Asian men – are descended from Genghis Khan. One busy man. But as Piper explains, this result is not particularly surprising: Genghis Khan had many wives and, as his family had strength, money and power, they would have survived the violence and disease that others of their era were subjected to.

Testing of the Y chromosome can also be used to help solve crimes, but Piper cautions that it differs from the more widely recognised DNA profiling. “This isn’t like DNA profiling where you can pinpoint one person to certain DNA. This is not about specific identification. It is about getting quick clues about what has occurred.”

Mitochondrial testing requires miniscule amounts of DNA, much less than DNA profiling. In fact, there can be enough DNA in a fingerprint to conduct a test. Also, mitochondrial testing doesn’t need any other samples of DNA for comparison, unlike profiling.

This means that if there is a crime or act of terrorism committed but no suspect profile, a mitochondrial DNA test done on trace amounts of DNA remaining at the site could provide a general nationality outline of the suspect.

Mitochondrial testing is useful in cases where fire has left very little DNA material, such as September 11, and in disaster victim identification where there are many unidentifiable victims, such as the Boxing Day Tsunami.

“The tsunami killed about 300,000 people, that is, 300,000 DNA profiles. Then we need to profile all the parents, that’s a further 600,000 tests: 900,000 tests in all – an insurmountable amount of work,” says Piper. “But using mitochondrial testing, we can at least narrow the victims down to nationality groups, and work from there.”