How It Works
Every event on this site comes with an estimate of when the last living eyewitness likely died (or will die). Here's the simple logic behind that number.
Who counts as an eyewitness?
We assume the youngest person who could have formed a real memory of an event was 5 years old at the time it happened. That's roughly the age at which people begin retaining lasting autobiographical memories.
How long did they live?
Life expectancy has improved a lot over the past century, so we use different figures depending on when the event occurred. We also add a small survivorship buffer — people who were alive to witness a major event were, on average, somewhat healthier than those who didn't make it that far.
| Event period | Life expectancy used | Survivorship buffer |
|---|---|---|
| Before 1920 | 55 years | +8 years |
| 1920 – 1950 | 65 years | +8 years |
| 1951 – 1980 | 75 years | +5 years |
| 1981 – 2000 | 80 years | +3 years |
| 2001 onwards | 82 years | +2 years |
The formula
Put it all together:
Last witness year = event year + 5 + life expectancy + buffer
For example, the Wright Brothers' first flight happened in 1903. The youngest plausible witness was 5 at the time. Using a life expectancy of 55 plus an 8-year buffer, that person would have lived to around 1971 — which means living memory of that flight is estimated to have ended over 50 years ago.
For more recent events the calculation projects forward, and the last witness may still be alive today.
Caveats
These are rough estimates, not precise historical records. Some eyewitnesses undoubtedly outlived these averages. The goal isn't accuracy to the year — it's to give you a gut feeling for how far into the past an event has truly slipped, beyond the reach of anyone who was there.