. >> stephen: that is a scrunchie. >> this is a scrunchie so 300 million years ago one member of a perfectlyde unsuspecting pair of chromosomes got a mutation, okay so we are gaeing to have to put this on here. and all right, like that. and. >> stephen: this is the dirty part. >> no, no-- . >> stephen: we have to blur that out, jimmy. >> so this acquired a sex determining gene. this one is becoming the y chromosome this one is going to become the x chromosome. but it turns out that after it acquired this sex determining gene, the y chromosome assumed some sort of funny behaviors. it stopped sharing information with its previously identical partner the x chromosome. >> stephen: it needed some me time. >> yeah, but it turns out that the isolationist behaviors on the part of the y chromosome led its economy to fail. and. >> stephen: led its economy to fail. >> yeah, yeah. >> stephen: is all of america a y chromosome. >> but let me tell you the full story. so the y chromosome started to deteriorate and a lot of stuff came off and then to make it worse, the x chromosome at the same time at the ex