The One Mother

There is a scrap of DNA you carry that came to you only from your mother, and to her only from hers — a thread passed down the female line, unbroken, never mixed with a father's. Follow every living person's thread backward and they all draw together, at last, into a single woman who lived in Africa perhaps a hundred and fifty thousand years ago. She is sometimes called Mitochondrial Eve.

But she was not the only woman alive, and this is the part most people get wrong. Her own world was full of women, with daughters and granddaughters of their own. She earned her title only in hindsight: she happens to be the most recent woman from whom every living person descends through an unbroken line of mothers. The others' mother-lines simply hit, somewhere down the centuries, a generation with only sons.

She was ordinary in her time. She became everyone's grandmother only by the slow accident of which daughters had daughters.

And if every mother-line leads to one woman — where does every father-line lead?