G25 PCA viewer
Plot your Global25 coordinates on ancient-DNA PCA views: project onto curated era spaces beside published ancient and modern samples, or fit a custom PCA over your own pasted rows. Free, no account, runs in your browser.
No account needed
Runs in your browser
Free
What a PCA projection shows, and what it flattens
Principal component analysis takes the 25 dimensions of a Global25 coordinate and finds the directions along which the samples spread the most, so the cloud can be drawn on a flat chart. This tool works in two modes. An era view projects your pasted row onto a reference space that was computed once, server-side, over that era's published samples — your point lands among ancient and modern individuals without moving any of them. A custom view fits a fresh PCA in your browser over exactly the rows you paste, which is the right tool for comparing a handful of coordinates against each other.
The two modes answer different questions, and swapping them silently is the classic mistake. In an era view the axes belong to the reference panel, so where you land is comparable across visitors and across sessions. In a custom fit the axes are recomputed from your own input — add or remove one row and every axis can rotate. A custom chart is a statement about your input set, not about any fixed reference space.
The limit to keep in view: a PCA chart shows 2 of 25 dimensions, chosen for spread, not for meaning. Two samples can sit near each other on the chart and be far apart in the dimensions the chart dropped — plot proximity is not descent, and no distance read off a PCA replaces the 25-dimensional distance the G25 distance tool computes. Everything runs in your browser; era reference spaces are public, read-only data, and the coordinates you paste are not uploaded.