alittletouched asks questions I like - nice Damascus edge.
If "alien", the notion of "training" and "loyalty oath testing" and the stagnation of the various cultures and their sudden disappearances could fit with a "basic training" regimen. At some point a recruit reports for active duty? Slavers-enslave, call in the motherships for pick-up. Farming.
"They take the white-trash first 'round here anyway", Steve Earle, Copperhead Road 1991.
They could tell time, they could understand planetary motion, built some strange architecture, they had language, mathematics, they may have understood aerodynamic and hydrodynamic concepts, they could kill their own, they had their own UFC-cum-field-team-sports, all very pliable assets - what's not to like? What still isn't to like? 'Doesn't even scratch the surface of the "weird" goin' on back then or now. Bright-enough, but not "too-bright". Fine soldiers.
Don't all human monumentally blood-thirsty cultures have "monuments"?
I'm trying to think of any that didn't/don't in their own way. Noble-beasts we. Have a Nobel.
The reasons for blood-sacrifice vary, the behavior does not. "Law" did/does that. And from where might such "laws" come?
"Reason" rhymed by rote, note for note. Author, author! Here Fido. Dawgma and just 'cause. (Winks to Alf)
The chicken or the egg? Seems to reason that the Sun was "happening" all along ('cept for those nasty eclipses on their version of a calendar widget) so... "sacrifice" was made to fit the existing local "need"? Maybe, maybe not. It could just be "shooting rubber-bands at the Moon", yet it was premeditated killing - here, let me cut your heart out, don't squirm it will only... This was thought of as "good". The trade in human-Albino parts is alive and quite well in Africa in 2009 too. Big human-ova bust in Romania today...
I liked Peru. Mexico was a waste of time. Chile was OK. Brazil a nightmare - missed Colares because of a strike. But even the various guides to the sights at the sites "vary" as to the "in-situ" story of the day.
Some make sense, most just make money - it's a racket even when it's not. Stagnant, banking on the calendar's-end in some places. Academics? Sorry, we only have entrepreneurs in stock these recessionary days. Academics of such esoterica as the "truth" are on back-order - have been for quite some time - lost in the signal to noise.
Stagnant. Without inertia.
I agree with kidflash2008 about growth... seems to me too that when there is really "interesting" human events - "they" may not be so far away. Crisis? What crisis? Time after time for thousands of years. Our "civilized" monumental moments and monuments would seem to support that idea of intervention even if only by anecdote - guilt by association. Maybe. Our "laws" may stem from "their" courtings amongst other peculiarities of our genus.
Who knows? Maybe "they" will be back as so many tales tell - maybe "they'll" have "friends", maybe "not-friends" too. Some say we already "cut a deal" - maybe bet on the wrong horse too. When it's time - we'll find out.