Commenter Melo writes:

An ad hoc assertion is essentially a hypothesis that has not been independently verified and is invoked to save a theory from falsification.

You’ve been doing that since I first started commenting here. To the point that the theory itself is just losing any real explanatory power it had. An example would be the statement that cold temperatures select for IQ but if the environment is too inhospitable, civilization will likely not emerge.

Actually it’s been independently verified over and over again and contradicted never. All six independent civilizations were created South of the Caspian sea by peoples who had spent tens of thousands of years outside the tropics. It’s one of the least ad hoc theories you’ve ever heard of because it has not a single exception.

So even though anatomically modern humans have been around for about 195,000 years, all six civilizations emerged 6000 to 3500 years ago. Coincidence? No. We didn’t evolve the cognitive ability to build civilization until we left the tropics and were exposed to the ice age, and even those who had evolved to the ice age could only build civilization if they ended up in bountiful land (i.e. South of the Caspian sea).

This perfectly explains both why civilization took so long, and why it was only created by certain peoples.

So because the IQ needed to build civilization evolved in high latitude (cold), but the lands amenable to civilization were low latitude (warm) it took our species 189,000 years before we had the right kind of humans on the right type of land during an interglacial period. These were humans who had migrated North but not too far North (i.e. Middle Easterners), or those who migrated as far North as the arctic circle, only to return to the tropics (i.e. the Mayans)