Much has been written about how the militarized response of local police made matters worse in Ferguson, Mo., following the Michael Brown shooting on August 9. Many point to the antiterrorism push to arm cops with military-grade weapons and gear following 9/11. But critical changes in community–police interactions—changes made as early as the 1800s—may have contributed to the tragedy with the creation of a permanent “siege mentality” on the part of police officers. Such attitudes can cause rifts between police and the community they vow to serve and protect—especially when coupled with long-standing racial or social tensions.

Scientific American