Mitochondrial EveY‑chromosome Adam⁠

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♀ Evemothers → daughters ♂ Adamfathers → sons

Each founding woman carries a unique mtDNA lineage (letter). Only daughters pass it on. Watch lineages die out until every living woman descends from one woman. Scroll the tree to look back through earlier generations.

Each founding man carries a unique Y-chromosome lineage (letter). Only sons pass it on. Watch lineages die out until every living man descends from one man. Scroll the tree to look back through earlier generations.

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Men's numbers of children vary more than women's: some have many, some none. That makes male lines die out faster, one reason the real Y-chromosome Adam and Mitochondrial Eve probably lived at different times, perhaps tens of thousands of years apart.

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Stats
Living lineages over time
Lineage share of living womenmen

Mitochondrial EveY‑chromosome Adam

In plain words. Your mitochondria, the tiny power plants inside your cells, carry a little DNA of their own, and you got it only from your mother. She got hers from her mother, and so on. Follow every living person's mother line back far enough and they all meet in one woman. She's called Mitochondrial Eve.

What she wasn't. Not the first woman, and not the only woman of her time. Many women then have descendants alive today, just not through an unbroken line of daughters: a line ends when a woman has only sons, or no children.

A bit more science. Mitochondrial DNA (mtDNA) is a small ring of about 16,600 DNA letters, passed on in the egg cell. It doesn't mix with the father's DNA, so it changes only through rare mutations, which build up at a fairly steady rate. Comparing the mtDNA of people alive today shows how long ago their lines split. Estimates place Eve in Africa, roughly 150,000 to 200,000 years ago. The title also moves: when one of the oldest branches dies out, a more recent woman becomes "Eve".

In plain words. The Y chromosome is the one that makes a baby a boy, so it passes only from father to son. Follow every living man's father line back far enough and they all meet in one man. He's called Y-chromosome Adam.

What he wasn't. Not the first man, not the only man of his time, and not Eve's partner: the two probably lived at different times. Other men of his time have descendants alive today, just not through an unbroken line of sons.

A bit more science. Most of the Y chromosome (about 57 million DNA letters) doesn't swap pieces with other chromosomes, so it's passed on almost unchanged apart from rare mutations, which are used to date when lines split. Estimates for Adam vary widely, roughly 120,000 to 300,000 years ago, also in Africa. Men's numbers of children usually vary more than women's (some father many, some none), and that makes male lines die out faster than female lines.

What the simulation shows

Nobody here is "fitter" than anyone else: every womanman has a random number of children. Still, by pure chance some lines have no daughterssons in a generation and end for good, while others spread. This is genetic drift. In a population of limited size it always ends the same way: one line is left, and everyone alive descends from one womanman.

Theory (the coalescent) says this takes about 2N generations for N womenmen, and fewer when numbers of children vary more. "Expected to converge" under Stats shows that estimate for your settings. Change "Variation among men" to see it shrink.

Reading the tree: each row is a generation, each circle a womanman, and the letter is the founder whose line they carry. Bright circles have descendants alive in the newest generation; faded ones don't. ⭐ marks EveAdam once all lines but one are gone.