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The number of my direct ancestors alive at any given time increases the further back you go. However, eventually that number is reduced to the handful who were the putative ancestral Eve and Adam, around 200 million years ago. When was the number of my direct ancestors that were alive together greatest, and how many were there?

Katka Kessler, Letchworth, Hertfordshire, UK

This article appeared in print under the headline 鈥淟iving in the past鈥�