Is "religious purposes" a kind of catch-all cliche? One doesn't have to think it's aliens to consider the necessary economics of building these things. You need to feed, water and house all the people doing it, their families can't be far, and those resources have to come from somewhere and someone has to collect and move them. Just a threat of force seems improbable, given the basic economics of that as well.<p>Celestial navigation or regional defence seems like the minimum probable reason. Also it's a desert with no landmarks except these lines. If you follwed those lines without the map, you might not know you were going in circles and you would run out of water and food pretty quickly. There are probably short cuts where sentries could see an advancing group following the lines and alert the settlement while the invaders took the long way in. Maybe prey animals would follow the lines in search of water as well separating them from cover and making them tired and easy to harvest. The directions could be transmitted orally and encoded pictorally without someone being able to see the whole picture.<p>These seem more plausible than "religious purposes," which tendentiously sets up religion as magical thinking, and the people who built these structures as irrational.
These are the geoglyphs the paper identified:<p><a href="https://ars.els-cdn.com/content/image/1-s2.0-S0305440323000559-gr6.jpg" rel="nofollow noreferrer">https://ars.els-cdn.com/content/image/1-s2.0-S03054403230005...</a>