Measuring History: Change of Units, Change of Perspective

History is usually measured in years. But what if the passage of time is measured in a different way?

In this post I want to share a simple idea I found staggering when I first came across it. Instead of measuring history in years, what happens if it is measured in generations? On the surface it doesn’t sound like this will make much of a difference, but I found the result was a big surprise.

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How long is a generation?

A generation is the time between someone being born and them going on to have children of their own.

In the UK in 2017, the average age of first-time mothers in the UK was 28.8, and the average age of women giving birth was a little over 30 (the second number is larger as it includes women having their second, third children etc.). The UK doesn’t keep statistics on the average age of first-time fathers, but the average age of the father of a newborn baby that year was 33.4. These numbers suggest at the present time a generation length of a little over thirty would be appropriate.

What about hundreds of years ago? The average ages in the last paragraph have all been going up for the last few decades due to changes in society, such as more women having careers in the workplace; an increase in university education leading to marriage and starting a family being delayed; and so on. So my initial thought was that a lower value for generation length would be appropriate in previous centuries – perhaps a value of 20 years.

I thought I would do a quick search on the internet to find out what values academic researchers use for generation length. This lead to an interesting article on the Ancestry website (if you don’t know it, Ancestry is a website that helps people find information on their ancestors and fill in their family tree). According to the article, several research projects by geneticists have found average generation lengths around the thirty mark for a range of cultures over recent centuries, with average male generation length a bit over thirty, and average female generation length a bit under thirty. The article also mentioned a study of a modern-day, stone-age-style tribe, which found figures of ~25 for women and ~35 for men: while the women started having children at a younger age than in the modern West, they kept having children for longer, so the average age at which women gave birth was still in their mid-twenties.

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Putting history into generations

Overall, in most cultures an average generation length of 25-30 years seems appropriate.

What does history look like if considered in terms of generations rather than years? In the chart below, I’ve listed some important historical events, and given their dates and roughly how many generations back they occurred. There is one column for an average generation length of 30 years, and one for an unrealistically low value of 20 years (to show what kind of a difference a low value makes).

What I found amazing when I first came across this way of measuring is how few generations there are to get right back to ancient times. Henry VIII and the Reformation are only 17-20 generations back, The Battle of Hastings 32-40, and Jesus and the Romans 67-80. And the whole of recorded history fits into a petite 200-or-so.

To me, 2000 years sounds like a very long time, but 70 generations doesn’t sound like a lot. 2000 years gives the impression of slow, gradual change. But fitting everything that has happened since the time of the Romans into 70 generations makes each generation sound busy and jammed full of activity. Human history doesn’t sound that long at all.

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What about trying a third unit of measurement – a “good old age”?

As far as I’m aware, no-one on my extended family tree has made it to the big 1-0-0, though some have come close. Life expectancy sky-rocketed over the twentieth century, but even today a figure of ninety-something is a good old age.

So what would we get if we were to measure the length of history in units of a modern “good old age”? Here’s what is to my mind an astonishing thought: someone who gets to the age of 90 has lived through and seen roughly one-sixtieth of the whole of recorded history. Wow. How crazy is that? One sixtieth! Recorded history is really not that long.

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Final Thoughts

In a sense the units used to record time don’t matter. The same amount of time passes however it is counted. But I find that counting in generations or lifetimes gives a real sense of perspective. Historical people and events suddenly seem closer to the present, and more relevant to today.

Have you come across this before? If not, what do you think? Are there any other ways of measuring time that fascinate you? If so, do leave a comment below; I’d love to hear about them.