Just as possible would be selection for _reduction_ in intelligence that reduces skepticism and limits thinking up objections to agitating emotion based calls for violence.
Likewise, lower intelligence might reduce personality differences and increased coordination. Individual troops with less foresight may be more careless of their own safety and thus more fierce on the battle field. In the manner of bees. Also, in a warrior society, obedience maybe favored over independent thinking.
Also, in an pre-agricultural societys everyone is a generalist: everyone must be smart enough to know how to do everything. Less true in agricultural societies.
So it's just as possible agriculture made people dumber but more dense population centers and thus more effective militarily.
My point is that barring actual measurement, we can conceive a great many possibilities and at this point no measurements indicate intelligence change over that period
I think this view is from a stereotyped but not really accurate view of warfare and it's reasons and execution. Warfare generally has very little to do with emotion. Even today, as always, it tends to be the same thing - one side has something and another side wants it. And in cases where you're not the side doing the taking, you need to be equally capable in war to defend what you have. Even things like religious warfare were more of a convenient casus belli for taking things than the cause entirely in and of themselves. This was a real risk all the way up until the 20th century. The thing that really changed the game was nukes which makes military dominance basically impossible, for now...
Similarly, throughout history it's invariably the more intelligent side that wins in war - at least in the longrun. The Mongols ended up wiping out a huge percent of the entire earth's population with an army that, for instance, when invading Europe only numbered in the low tens of thousands and were very lightly armored compared to the forces they were fighting. But they were smart in war and strategy and had relatively advanced technology in their composite bows. That the Mongoloid group of peoples to this day still have a substantially higher IQ than average I think is at least a reasonably strong correlation in support of selection for intelligence.
Neanderthals had larger brains than we do. If intelligence was the determining factor in out-competing rivals, we would expect all species to evolve greater intelligence at the cost of other adaptations. This is clearly not the case: only one species invented the gun, all others went with sharper teeth. Even now there are more sharks than dolphins, more reptiles than mammals, more insect than reptiles.
But in humans, the very idea that "we" fight to gain "their" requires creating an "us vs them" dichotomy. But all humans are the same species, and persons on national borders are invariably more closely related than on opposite sides of the same country.
Essentially every border is an accident of history: Romans building a wall, Charlemagne having so many heirs, monarchs marring one person vs another, religious boundaries becoming national ones, the treaty of Versailles drawing straight lines through deserts.
To convince people that a particular "us vs them" dichotomy is real requires the listener to have a certain kind of thinking processes. Especially to convince them to kill and die for it.
And because every population falls for this, any individual population that smartens up and notices it's absurd will likely be wiped out by those who still have the "us vs them" delusion. Thus the species is kept in a sub-optimal state.
That 19th century definition of Mongoloid is nonsensically arbitrary, so instead I was interpreting it in as generous a way as possible: residents of Mongolia or Haplogroup C3
The closest relatives of Genghis Khan, whom he claims is the source of superior intelligence, live overwhelmingly in modern day Mongolia and Kazakhstan. They are more related to Navajos than to modern Chinese, Japanese, Koreans or whoever else fits in that 19th century definition of "Mongoloid".
Likewise, lower intelligence might reduce personality differences and increased coordination. Individual troops with less foresight may be more careless of their own safety and thus more fierce on the battle field. In the manner of bees. Also, in a warrior society, obedience maybe favored over independent thinking.
Also, in an pre-agricultural societys everyone is a generalist: everyone must be smart enough to know how to do everything. Less true in agricultural societies.
So it's just as possible agriculture made people dumber but more dense population centers and thus more effective militarily.
My point is that barring actual measurement, we can conceive a great many possibilities and at this point no measurements indicate intelligence change over that period