All Your Ancestors

Ten thousand years of one family, flowing from a single person. Every stream is a lineage; the width of the river is the share of the living world it contains — until the streams fold into each other and become everyone.

father’s father father’s mother mother’s father mother’s mother every lineage, merged

Width is drawn to scale left of ~1200 CE. Nearer the present the true widths are microscopic — two parents are 0.000000025% of the world — so streams are drawn at a minimum visible width and spread apart for legibility; position there encodes lineage, not quantity. Hover anywhere for the true numbers.

How to read it

Start at the right: one person, born 1976. Each generation back, the ancestor slots double — 2, 4, 8, 16 … By twenty-nine generations (~1164 CE) the tree demands more ancestors than there were people alive on Earth. The only resolution: the same people fill many slots. Cousins married cousins, lineages folded together, and the streams merge.

Left of the merge, the river is one braid, and it widens as it runs into the past — by the identical ancestors point (~5,000–7,000 years ago), every person alive then either left no descendants or is an ancestor of everyone alive today. The band never fills the field: the margin above and below is the ~23% of every era whose lines simply ended.

The paper trail in this tree

The bright bars under the fan are real: 338 named ancestors in Owen’s documented tree — complete through generation 5 (all 32), 44 of 128 at generation 7, and by generation 14 just 2 names of 16,384 slots. The earliest documented birth is 1515. The mathematics of pedigree collapse is also documented here in miniature: two of Owen’s great-great-grandparents were Carpenter cousins of a Kentucky family, folding one branch of this very tree onto another.

And a humbling footnote: past roughly 7–10 generations, most named ancestors contributed no DNA at all — genealogical ancestry outruns genetic ancestry almost immediately.

Model & sources

The height of the river at any date is the modeled share of the world’s population then alive who are the subject’s ancestors: ancestor slots 2^g (28-year generations) colliding with an accessible population — a regional pool (~7% of world) that widens to the whole world going back, times the ~78% of any era who left descendants. Calibrated to Chang (1999) and Rohde, Olson & Chang, Nature 431 (2004): most recent common ancestor ~2,000–4,000 years ago, identical ancestors point ~5,000–7,000. World population from McEvedy & Jones / HYDE-style estimates. The curve is a calibrated model, not a measurement — the shape and the milestones are what is known.

The numbers behind the drawing

Generation	Year	Ancestor slots	Distinct ancestors (est.)	World population	% of world