This by itself indicates warfare. City walls are huge, costly infrastructure projects that require serious justification for both construction and maintenance. For instance, in contemporary Mesopotamia cities only began to build walls with the emergence of serious warfare at the beginning of the Early Dynastic period (ca. 2900 BC).
> scientists find no layers of ash that would suggest the city had been burned down, and no signs of mass destruction
As the main evidence in the article this is unimpressive. Warfare does not usually result in the mass destruction of cities. E.g. Medieval England had endemic warfare for centuries but London, Bristol etc. didn't get burned down. Factors such as siege methods and building materials also make a big difference in how cities are affected by warfare.
Indeed, the article just casually mentioned city walls without countering the obvious that city walls are normally built in an environment with warfare. City walls is something you do not build unless you really have to. We stopped building them once they stopped being cost effective.
To those who have seen the remains of structures exposed to floodwater, this will seem unlikely. The way to deal with floods, if you must live on the floodplain, is to build levees, berms, dikes, etc. Huge piles of rock and dirt, miles long and scores of yards wide, stacked and compacted by hordes of zero-skill labor. Not tiny little stone walls, crafted by masons who would have been among the most skilled artisans a Stone-Age society could have.
Often times animal predators are detoured by wooden fences just as effectively as 10 foot tall, 3 foot thick stone walls. You only build the later if you enemy is a bit more tenacious then an animal predator.
> Often times animal predators are detoured by wooden fences
Heck, often they're repelled just by the sight of fire or a solitary guard.
More often than not the less-timid ones just scavenge human scraps, return, and start to hang out. This is how dogs became domesticated many thousands of years ago...
This by itself indicates warfare. City walls are huge, costly infrastructure projects that require serious justification for both construction and maintenance. For instance, in contemporary Mesopotamia cities only began to build walls with the emergence of serious warfare at the beginning of the Early Dynastic period (ca. 2900 BC).
> scientists find no layers of ash that would suggest the city had been burned down, and no signs of mass destruction
As the main evidence in the article this is unimpressive. Warfare does not usually result in the mass destruction of cities. E.g. Medieval England had endemic warfare for centuries but London, Bristol etc. didn't get burned down. Factors such as siege methods and building materials also make a big difference in how cities are affected by warfare.