Answer:
By examining graves at Chaco Canyon, archaeologists found evidence of warfare, cannibalism and scalping. There was also evidence that shelters were built in protected places, possibly to defend themselves against enemies.
Explanation:
The archaeologists discovered that over time there were fewer and fewer pinion and juniper trees. Then, the trees completely disappeared. Since pinion and juniper were used for firewood and food, that means that humans had to adapt to living in treeless scrub. When trees are cut down, the land is warmed more by the sun, creating dryer, hotter weather. The packrat nests also showed us that game was getting scarce and that people were eating rabbits and mice instead of deer.
