The final chapter of Sapolsky’s book is one of the longest, presenting evidence that the worst of human behaviors are becoming less prevalent in society while our best ones are ascendant. Throughout the chapter, he highlights how several factors of brain biology he has already covered, including learning-to-automaticity, reappraisals of Us/Them relationships, empathy and cultural conditioning, can lead individuals to become their best. Like the chapters before, this is a massive application of all the science of behavior we have previously seen to a major social issue.

In the year 1800, slavery, child labor, and animal abuse were legal across the globe. Renaissance Europe averaged 41 homicides per 100,000 people per year. Today, it’s 1.4 (though some global nations of today exceed Renaissance rates). Sapolsky lists several more horrors of the past currently declining—“persecution of homosexuals […] beating of schoolchildren […] death in childbirth […]” and several more recent moral inventions, such as “the concept of crimes against humanity […] agreements to hinder trafficking of blood diamonds […] industries that battle global pandemics and send medical personnel to any place of conflict” (615). Sapolsky also recognizes such rules are not universally enforced, and humans across the globe can still do quite horrific things to each other.