Image from http://www.thetimes.co.uk/tto/multimedia/archive/00380/RichardIII_380709a.jpg |
What the team did was scrape together a DNA profile from a very old skeleton. Since the DNA was so old and damaged, scientists had to look through millions of ribbons of splintered DNA strings. Also to make sure the analysis wasn't contaminated, scientists did the sequencing in multiple clean rooms at multiple locations. Then the profile was compared to Richard III's living relatives. That was still difficult though because an ancestor from 20 generations back would only contribute .000001 of an individual's DNA. What does go almost unchanged through generations is mitochondrial DNA and the DNA on the Y chromosome. Mitochondrial DNA only comes from the mother allowing scientists to look at an all female line through the family tree. It was discovered that the descendants had the exact same mitochondrial DNA except for 1 single mutation. Richard did not have a pure male-line descendants making the tracking of the Y chromosome difficult. The team had more than enough information though.
I thought this was extremely interesting and relevant to class because we were looking at case studies similar to this with mummies and learning about how difficult it is to extract DNA from the dead and how there is a great risk of contamination. It is amazing what can be done with information on someone's DNA.
Article: http://www.popularmechanics.com/science/health/genetics/scientists-confirm-remains-king-richard-iii-17487010
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