So I was reading Alan Furst’s new novel “The Spies of Warsaw” when I was struck by a particular passage.   A typical Furst protagonist, the world-weary French Colonel Mercier, is attending a grand reception in Warsaw with a typical Furst heroine, the luscious and mysterious Anna Szarbeck.  It’s 1937, and war is coming. She’s chatting with various strangers:

“So, you’re with the League of Nations.”  The woman was in her seventies, Anna thought; her husband, with grand white cavalry mustaches, at least in his eighties.  “Such a hopeful notion, my dear, really.  A league, of nations!  How far we’ve come, in this dreadful world.  My husband here, the general, was the late-life son of a colonel in the Hussars.  In 1852 that was. A great hero, my husband’s father, he fought in the Battle of Leipzig and was decorated for bravery – we still have the medal.”

“At Leipzig, really.”

“That’s right, my dear, with Napoleon.”

The Battle of Leipzig was in 1813, and was the largest battle in Europe before WW I, involving 600K troops.  If the husband’s father was 21 then, he would have been 60 in 1852, when the general was born.  That’s old for a father, but not terribly old.  Of every 100,000 births, between 20 to 100 are to men of that age.  If the general himself had had a child at 60 in 1912, that child would be 97 today.  Again, old, but not unheard of. Adjust those ages a little bit, and a man who had a son at 70 who himself had a child at 70 would have a grandchild who would now be 76.

So a person living today could have a grandfather who fought in the Napoleonic Wars.  It only takes three lifetimes to cover the modern era.   Three lifetimes to go from sailing ships to robots on Mars.   Three lifetimes to cover the Industrial Revolution, the rise of democracy, the 10X explosion in world population.

But then, all of human history is short, maybe 5000 years.  My own lifetime covers 1% of that, and I’m just some guy.  It would only take 100 lives like mine to cover it all.  You too have probably personally experienced a significant percentage of all of history.

How can that be?  Maybe because of that population explosion.   The total number of people who have ever lived is somewhere around 100 billion.  There are almost 7 billion of us right now.   If you ever lived, there’s a 7% chance that you’re alive right now.

Update 9/4/17: A case has been found of the above!  The site Mental Floss noted in 2012 that President John Tyler has two living grandsons.  Tyler was born in 1790, and was president from 1841 to 1845.  He was a captain of a militia company in the War of 1812, which counts as a spinoff of the Napoleonic wars, but saw no action.  He had a son, Lyon Gardiner Tyler in 1853, at age 63 by his second wife.   Lyon then fathered Lyon Gardiner Tyler Jr. in 1924, and Harrison Ruffin Tyler in 1928 when he was 71 and 75, again by a much younger second wife.   Both are apparently still alive at ages 93 and 89.  Harrison is still in the family home in Virginia.  That’s three generations covering 227 years!   Neither Lyon Jr or Harrison have second wives, so their family’s extremely long generations stop with them.