None of that Adam and Eve crap ;)

They looked at thousands of genes in the Y chromosomes of two Chinese men. They knew the men were distantly related, having shared a common ancestor who was born in 1805.

By looking at the number of differences between the two men, and the size of the human genome, they were able to come up with an estimate of between 100 and 200 new mutations per person.

And why is this so special?

New mutations can occasionally lead to severe diseases like cancer. It is hoped that the findings may lead to new ways to reduce mutations and provide insights into human evolution.