These are links that I’ve had trouble finding in the past
http://jasss.soc.surrey.ac.uk/16/3/7.html – a related 2013 ethnocentrism paper with an amusing .gif illustrating the results
http://www.ribbonfarm.com/2016/05/05/dares-costly-signals-and-psychopaths/ – an essay by Sarah Perry on Ribbon Farm, pushing the hypothesis that a lot of seemingly-anti-social youth behavior is looking to elicit involuntary affect, lack of which is a sign of sociopathy
http://afe.easia.columbia.edu/ps/cup/xunzi_encouraging_learning.pdf – The Xunzi essay with the quotation, “Once I spent an entire day lost in thought, but it was not as good as a moment of study.”
http://www.kevinmacdonald.net/paper-Evolpsych.html – At the moment, CSULB seems to have locked off all the .pdfs that KMac used to host on his homepage, but the links are all here.