Deliberate human breeding will do that.
http://miriamhakedosha.blogspot.com.au/2010/05/ireland-velikovsky-and-tutankhamun.html
“...The mutation change rate of dna is causing some problems for those who advocate the evolutionary position. Studies of Y-dna have shown that there are two kinds of y-dna mutations. Firstly there is a stable paternal system that is said to be much slower in mutating than mt-dna. This first sequence is believed by evolutionary geneticists to take tens of thousands of years to mutate for a single mutation between groups. Secondly there is a sequence that is much faster in mutating. This second sequence is like a stammer, and the y-dna gains or loses one of these sequences much quicker. This loss and gain results in separating the Haplogroup into hundreds of male lines. These mutations are said by evolutionary geneticists to occur every 1,500 years, give or take a few years. Studying the y-dna of certain families of the Niall clan of M222 in the US and Britain have demonstrated single-step mutations in less than two hundred years. Thus the mutation rate is not 1,500 years but around 100-200 years for each mutation step. The mt-dna mutation rate is said to be 20,000 years by the evolutionary geneticists- this also is ridiculously too long...”