The good old days, when reaching 18 was considered 'old age'

Be grateful you're living in 2025. While there are plenty of problems, it could be worse. If you were living in 50,000 BC, you would likely have died decades ago (well, 52,025 years and decades ago). The same for living in 1200. Or even 1900, for that matter.

Here's why: According to a 2011 report included in an article that estimates how many people have lived in world history, the average life expectancy in 50,000 BC was 13. Thirteen! Forty-two thousand years later, all the way to 8,000 BC, the average life expectancy was . . .  still 13. That explains why so many parents in that era didn't invest in braces for their kids. It was unlikely they'd benefit. (That trend was so significant that there is no evidence of orthodontists in 8,000 BC.)

Over the centuries, lifespans got a little longer, but only a bit. By 1750 (when we were only 16 years away from the Declaration of Independence), the expected lifespan was 28. By 1900, it was just 38.

That's right. The average person in 1900 would barely make it to their 20th high school reunion. Or, more accurately, to the 30th reunion of third grade, when they quit school to work in a mine.

Now? The average lifespan is 73 and rising.

So yeah, these are the good old days. Being a 20-year-old now isn't old age. Reaching 40 isn't a time to have people toast your longevity. As they say in some 50,000-year-old hospitals, 73 is the new 13.

How short lifespans have been over the eons was a takeaway from an article that challenges the assertion that about 117 billion people have lived. (You've never heard that assertion? Neither had I.)

Those estimates vary greatly. The author points out that some people say that about 170 million people were on earth in C.E. 1 (formerly known as 1 AD), while others say there were about 300 million at that time. The author uses a complicated math formula (more complicated than figuring out a batting average!) to include the fact that you and I being alive now was predictable 20 years ago. Calculating the population in Earth's history isn't as simple as figuring the population each decade and adding them all together, since people live multiple decades (also, census data from 45,000 BC is notoriously inaccurate).

His estimate is that 93 billion people have lived, a significantly lower number than the standard. Beyond that, there's one big takeaway for me.

The world's population has grown dramatically in recent years not because the birth rate is high, but because the death rate is low. Even as late as 1750 or 1900, people died dramatically earlier than they do now, so the world population didn't grow fast despite the fact that families often had six or 12 or 15 kids.

A point of evidence: Between 7% and 10% of all people aged 65 or older who have ever lived are alive now. 

So today, you're smarter. You know three things:

1. It's reasonable to think about 100 billion people have ever lived.

2. Nearly 10% of all people 65 and older who have ever lived are alive now.

3. If you're 30 or 40 or 50 or older, you would have been a remarkable survivor in 50,000 BC. Or 8,000 BC. Or even 1750.

Had you lived centuries ago, you would have been considered amazing, although you'd also be susceptible to the Black Death or malnutrition. So there's that.

Reach Brad Stanhope at bradstanhope@outlook.com.