Exceptionaly well documented and written article detailing the well known techniques used to build the iconic stone work in south america. I read an earlier account of a researcher who started investigating pre spanish south american quaries, and how there sudden realisation, while sitting down for lunch, that the round stone to there right, was the hammer used to shape the larger stone to there left and the rows of peck marks ending in raw stone, all of those centuries before. Having worked a bit of stone myself, learning to shape, temper stone drills, and test them for utility, it is very easy to understand how basic pragmatism and persistance, in stone, yields large structures that retain that essential message of we are not messing around in this effort, and your opinions can only embellish this. When considering stone articacts of any scale, it is always best to keep in mind that lithic technology pre dates our "species", and our evolutionary track is directly parallel with it, and there is quite litteraly, mountains of evidence for this.And should you so wish, any modest effort to go look, dig, search the ground, known hunting areas or settlement zones, will yield physical evidence that anyone can examine. our development of technology