Historical Birthrates

Y’know the good ol’ days when everyone had ten kids?

Those days never existed.

Or, to be more precise: The never existed for more than a few people in particular areas in particular historical circumstances.

The family my cattle-ranching grandmother was born into, f’risntance, had 12 kids, 10 of whom survived to adulthood.

But that’s always been the lucky exception. Not the rule.

How can we know that?

We can do the math.

Suppose Adam and Eve had four kids (Scripture says they had more, but suppose it was only four).

Suppose that their kids paired off and each pair had four kids, just like Adam and Eve.

That’d be eight kids in the next generation.

Now suppose this patten of four kids per couple kept up each generation.

Y’know how many generations it would take to arrive at the 4 billion folks who were alive c. 1980? 32 generations.

Remembering, though, that more than one generation is alive at a time, let’s suppose that two generations were alive at any one time (that would be some grandparents, all parents, and some of the children who would be born; we’ll ignore great-grandparents and great-grandchildren for statistical purposes since so few of these have been alive at the same time before the advent of modern medicine).

Y’know how many generations it would take to get to the six billion people currently alive at present? Again: 32.

Now suppose that on average historically parents had their children four children between the ages of 15 and 45, so the parents were an average of 30 years old when they were between their second and third of their four children.

Y’know how long ago Adam and Eve would have lived? That would be 960 years (32 generations x 30 years at middle of breeding life).

Hm. Doesn’t sound right, does it?

But wait! Maybe there are some factors we haven’t accounted for! Let’s try an easy one: Not everbody gets married. Some people go through life single–or they’re in an infertile union and can’t have kids. Let’s suppose that happens to half of all the children that have been born historically: They either stayed single or couldn’t have kids.

In this case, each generation of parents could have eight kids, with only four of them going on to have a brood of eight kids, four of whom would then reproduce, etc. If only half the kids end up breeding due to singleness or infertility, y’know how many generations that would push back Adam and Eve from the present generation?

One.

In that case, the human race would be 33 generations and 990 years old.

But maybe there are other factors–like disease and war. Those have claimed a lot of people’s lives and kept them from breeding. Suppose that these two factors cut each historical generation in half. In that case, each previous batch of parents would have had 16 kids–half of which were prevented from breeding because of illness or war. Of the eight surviving kids, four didn’t breed because of singleness or infertility, leaving four to find spouses and breed a new batch of 16 kids, only 4 of which would then go on to breed, etc.

How far back would that push Adam and Eve?

One generation.

In that case the human race would be 34 generations and 1020 years old.

Okay, so maybe there’s another factor.

How about the obvious one, biblically: The hugelarge lifespans that the early chapters of Genesis record?

Assuming those are literal, they do create some extra room between us and Adam and Eve. But not as much as you’d think. While Adam may have lived to be 930 years old according to Genesis 5:5, he had his third son–Seth–when he was only 130 years old according to Gen. 5:3. That’s not unusual in the Genesis 5 genealogy. The patriarchs tend to have their kids (relatively) young compared to their hugelarge lifespan (I am so envious of that lifespan, lemme tell you), and it’s the kid-bearing age that counts for making Adam and Eve more remote from us, not the overall time the partiarchs lived.

Those (relatively) high kid-bearing ages also only apply to the first few generations of the human race. Things drop off pretty quickly after the time of Noah.

But there’s a bigger problem.

Even if we give full allowance for pushing Adam and Eve back in time based on the long lifespans recorded in Genesis, that doesn’t change the number of generations between them and us. And therein lies the problem.

If y’all will take a gander at the genealogy of Jesus Christ offered in Luke 3, y’all’ll see that there are 76 generations between Adam and Jesus–and that was 2000 years ago. Allowing for the 30 years per breeding generation over the last 2000 years, that would mean that there have been 67 geneations between Jesus’ day and today, meaning that there have been 143 generations between Adam and us.

Now that’s a problem if you want to say that folks in the past had large numbers of kids on average.

Y’know how many people would be alive today after 143 generations in which each pair of parents had an average of only four kids who went on to breed? (Leaving aside those who were single, infertile, or killed by disease or war.)

There would be 16,725,558,898,898,000,000,000,000,000,000,000,000,000,000 or almost 17 tredecillion people.

The only conclusions available would be (a) there are this many people alive now, despite appearances, (b) the human race is much less than 143 generations old, despite the Bible and science, or (c) the average number of children folks have had who went on to breed is less than 4–way less. Still above 2 or we’d never make any progress at all, but way less than 4.

My money’s on the last of the three options: The average number of breeding kids folks historically have had was much closer to 2 than 4.

If I’ve done my math right, it would take an average of 2.33 breeding children per generation to arrive at the present global population after 143 generations.

If there were some missing generations in the biblical genealogies (as is likely) then the number would be less than 2.33 but still higher than 2. For simplicitly, let’s assume that it’s 2.33, though.

How we account for this number is an open question. Certainly they had more kids than became breeders. Some stayed single. Some were infertile. Some died from disease. Some died from violence.

But I doubt that most parents had 8 kids and only 2.33 ended up becoming parents. I suspect that the historical number was much closer to 4 kids, of which 2.33 became parents.

Yet that number isn’t realistic for parents who aren’t otherwise touched by infertility, disease, or war, which we have already accounted for (on average). If you have two folks get married at 15 and they start having a typical conjugal life then–barring infertility, death by disease, and death by war–they’re going to have a lot more than 4 kids before they hit 45.

This suggests one thing: Folks in the past have been far better at birth regulation than we in the modern world have given them credit for.

Much of the time, no doubt, due to pagan influence and lack of doctrinal clarity, they have used things like abortion and contraception to regulate birth in a morally illicit manner, but even in properly-morally-educated Catholic countries they have been exercising a lot more regulation of births than we’ve been imagining.

After all, if we started with just two good Catholics 1000 years ago in Europe and they had and average of four breeding kids per generation then there would be six billion such European Catholics today.

And there’s not. Nowhere close.

Now, don’t get me wrong: I love big families. I’d love to get married and have one. I’d love to see folks all over the place having them for the indefinite future, including starting colonies offworld to get elbow room for all the new humans. (Take a look in the chart above around generation 36 is you don’t see the need for new elbow room for them.)

But I also believe in looking at the past realistically, and at human nature realistically, and human nature is such that the idea that the regulation of births has only come into view in the last generation or two just doesn’t hold water.

Right or wrong, by good means or bad, the regulation of births has been with us much, much longer.