Some thoughts on the late teen/early adult years.

The gun control bill that passed the house proposes to raise the purchase age for firearms to 21.

Teenage soldier, i.e., me. 1982.  At that age I was plenty mature enough for this role.

The counterargument is somewhat predictable for this.  "If you can serve in the military at age 21 and carry a weapon for your country. . ."

But why can you do that at age 21?

Under the original U.S. Constitution you couldn't vote until you were 21 years of age, that being the age at which the founders deemed a man (and originally it was just men) mature enough to participate in the serious business of choosing a government.  The age was changed in the late stage of the Vietnam War, under the logic if that if you were old enough to fight for your country, you were old enough to vote and participate in the decisions that led to the fighting.  That reflected the conscription age at the time, which had reached down to 18 for most of the war, even though, as noted above, it had climbed a bit late war, and even though teenage soldiers in the Vietnam War were actually fairly rare.

All the states had militia duty requirements at the time the Constitution was enacted, as the colonies also had them prior to that and dating back to their founding. Most of these made men liable for militia service between 18 and 45 years of age.

The Federal Government didn't conscript men into military service until the Civil War, at which point it passed a bill during the war making men from age 20 to 45 years of age eligible for conscription.  The southern rebellious states passed a federal conscription provision which at first covered ages 18 to 35 and then later ages 17 to 60.  The South had a real manpower problem, it might be noted, and at the bitter end of the war, it made slaves liable for conscription, demonstrating that, because there's no reason to believe they would have made willing soldiers against their own best interest.

The draft ranges for conscription during World War was fell between age 21 and 30. The first draft range for World War Two was from 21 to 35, but as the war went on it dropped to 18 years of age and up into the 40s for the upper range.  Starting in 1948 men were eligible again for the draft at age 19.  It dropped to 18 during the Korean War and stayed there until 1969, when Nixon ordered it back up to age 19.

We lack conscription now, of course, but men between the years of 18 to 35 are liable under the Selective Service provisions to conscription and are "obligors" under the law.

Hmmmm.

Interestingly, the mid 20th Century also saw men start to graduate high school as a rule, which is also at age 18.  High school graduation rates overall, for men and women combined, rose from 6% in 1900 to 80% by 1970, near the end of the Vietnam War.  The American system of education developed such that schooling normally completed, as noted, around age 18, although some did graduate at 17 when I was a high schooler, and some at 19.  As late as the late 1930s only around half of the male population graduated from high school, but that was very rapidly changing and soon after the war most men and women graduated.

In every U.S. state you can marry, the most serious thing a person can do, and marry freely, at age 18.  While people who like to get spastic about it misconstrue it, you can marry below that with permission of your parents or authorities in most states younger than that.  18 years of age in order to contact a marriage is the global norm, interestingly, although there are some exceptions.  Honduras, for example, sets the age at 21.  Japan at 20.  The Philippines at 21.  A few nations set the minimum age for women, oddly enough, below 18, usually at 16 or 17.

The other "age of consent" is generally age 18 in the United States, although there are all sorts of other rules and factors that go into that, so it's not really safe to opine on.  What's safer to opine on is that generally in the US women become far game for male predation at age 18 and that's the age where it's generally legally safe for them to be subject to all sorts of creepy behavior.  The same is true for men, but it's women that are largely the victims in this area, although not exclusively so.

In the US, the drinking age everywhere, due to Federal pressure on the topic, is 21. When I was 19, the drinking age in Wyoming was 19, which it had been dropped to during the Vietnam War due to the same logic that prevailed regarding voting.   

As of 2019, the minimum age to buy tobacco is 21.  In most of "progressive" Canada, it's 18.  Where it isn't 18 in Canada, it's 19.

In much of the US, you can drive at age 16.  This is true in Canada and Mexico as well, but the global norm, although there's lots of variety in it, is 18.

In most of the US you have to be at least 20 to rent a car, although as a practical matter, that age is really 23.

Odd, isn't it?

Research has determined that the male brain continues to develop until age 25, which is when men basically reach maturity, whereas for women it's 21.  Some studies push that up to 25 for men and women. A British study found that men reach full emotional maturity at approximately age 43, whereas women do at 32, which is a bit of a different thing than developmental maturity.

Which brings us to this.

The founders setting the voting age at 21 reflected their actual experience.  People like to imagine that everybody did everything younger back in the day, but this isn't really the case at all.  As we've discussed here before, actual marriage ages haven't changed hardly at all since the Middle Ages.  They'll occasionally go up (usually due to economic conditions), and rarely go down, but they return to a well established median.   The current "everyone is getting married older" story really reflects the latter.

Marriage, rather obviously, was allowed at a younger age than 21, but there are biological factors at work there that would tend to explain that, at least up until the government became the substitute daddy allowing men to evade responsibility for their offspring.

The odd thing about age in the early history of the country was the age for compulsory bearing of arms was 18.  Why?  No idea.  When conscription first came about, it was set at age 21, the age you could vote, and remained that age until the Second World War, when it was dropped to 18.

Driving ages are at low ages in North America because of farm economies.  Lots of drivers were, at one time, young farm drivers.

Which brings us to this.

The current pattern of living may reflect the historic norm in the US more than we suppose.  We've dealt with it before, but up until World War Two, the basic norm for most men was to leave high school, by graduation or otherwise, and then go to work.  Most men lived at home until they married.  Most women lived at home until they married. And for most, they were 21 years of age or older at that time.  The World War Two period brought in a demographic and behavioral exception, but it was due to external forces.  Large scale conscription and a booming economy, following the Great Depression, followed by the massive expansion of the economy and higher education.  The trend that started in 1939 lasted a few decades, but we've seen a return to the older pattern of living more recently.

Which perhaps gets back to this.

The new gun control provision probably makes a lot of sense.  There are reasons to preclude people who have not reached maturity from buying firearms.

But there are probably reasons not to allow them to do other responsible things as well, including voting.

Maybe, looked at this rationally and scientifically, the military ought to not be open to enlistment until age 21.  Maybe the "age of consent", or exploitation, ought to be 21.  Maybe public education ought to expand up to age 21.