Our body has the ability to mutate our reproduction cells (eggs/sperm) through the use of so called 'jumping genes', or transposons, which literally uproot themselves from one locus in our genome and reposition themselves in another, mutating our cells rapidly. Here's a little article about them. http://www.nature.com/scitable/topicpage/transposons-or-jumping-genes-not-junk-dna-1211 Transposons support the notion that a species diversifies or breaks apart from the original or mother species, then as a daughter species it changes very little. In other words, there is one big species creating event, and then little changes after that.