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Looking to DNA to understand what makes us human


Narrator:    This is Science Today. Chimpanzees are our closest living relatives. In fact, the genetic codes of chimps and humans are 99 percent identical.

Pollard:    One percent difference doesn't sound like a lot, but then you have to remember that there's about three billion letters in the genome, so one percent is still millions of letters.

Narrator:    Katie Pollard is an associate professor at the University of California, San Francisco's Institute for Human Genetics.

Pollard:    Fifteen million human-specific changes have happened in the last six million years. So, it's not completely trivial to go through each of those and think about what difference it might have made.

Narrator:    Pollard and her colleagues are comparing the genetic sequences of humans and chimps more closely than ever to find out what is it about our genes that enables us to develop uniquely human capabilities? In fact, Pollard created a software program that can tease out such information from DNA.

Pollard:    We want to use these techniques to try to figure out which of those 15 million changes are the ones that most likely made a difference.  

Narrator:    For Science Today, I'm Larissa Branin.