Could an evolutionary biologist out there settle an argument for me? The other party in this dispute says that Mitochondrial Eve keeps changing because of 'broken lines'. My position is that everyone alive today has a mother, and everyone's mother has a direct female line back to 'Eve'. As far as I can deduce, 'Eve' is not going to change unless there is another human bottleneck that wipes out most humans and brings about another 'Eve'. Is my opponent confusing Mitochondrial Eve with our Most Recent Common Ancestor (human)? Wikipedia seems to say the same thing as the other party. Am I missing something here? I'm probably not as confused as many people, so please don't be too withering.