All hermaphroditic eukaryotes (including humans, of course) have an organelle called mitochondria, which is the place where cells produce energy and the "energy factory" of cells. Mitochondria have their own genes, and the number of genes is only 37, with little change. Moreover, mitochondria are parthenogenetic, only inherited from maternal eggs, and do not involve paternal sperm cells. When an egg forms a fertilized egg, the nuclear genes of both sexes will be partially exchanged, crossed and rearranged, but the mitochondrial genes will not happen, and only point mutations will occur at a basically fixed frequency. Therefore, as time goes forward, there will be more mutations, but if we go back, there will be fewer mutations, and eventually there will be only one prototype instead of all the existing mutations. At this time, we will say that we have found the mitochondrial ancestors of all people now. By tracing the pedigree of mitochondrial genes, it was found that there was a crossing point about 6.5438+0.4 million years ago, indicating that all the existing mitochondrial genes were handed down by a woman 6.5438+0.4 million years ago. She is vividly called "Mitochondrial Eve".
Similarly, the Y chromosome that determines the male sex in the nucleus is parthenogenetic, except that it is paternal and passed down from generation to generation. By comparing the differences of Y chromosome sequences among individuals, we can also calculate that all the Y chromosomes appearing in people came from a person about 60,000 years ago. He is called "Y chromosome Adam".
The so-called "Eve" and "Adam" are just figures of speech. It doesn't mean that there was only one woman or one man at that time. They didn't live in the same era. On the contrary, there must be many women and many men living at the same time, but their mitochondrial genes and their Y chromosome genes have not been inherited until now. But they inherited other genes. "Mitochondrial Eve" and "Y chromosome Adam" probably have no other genes except mitochondria and Y chromosome.
In other words, human beings are just genes in mitochondria and genes in Y chromosome may come from a certain woman and man, but other genes come from countless other ancestors, both women and men.
People on the earth are descendants of countless "Adam" and "Eve".