That, plus the fact that only the mitochondria from the mother get into a new mammal (via the egg) , makes mitochondrial DNA easier to track across the generations than the stuff in the nucleus.

• 加上线粒体只经过母体（卵子）遗传到下代哺乳动物的特性，跟踪线粒体的相代遗传比跟综胞核要容易。