In response to:
Broadly, I think there is a much longer social trend away from unrepentantly selfish, dominance-based behavior within all levels of authority. We still have boom-and-bust cycles that coincide (or precipitate) the decline of empires, be they national or business, but each new cycle shaves away a bit more of the worst behavior and adds a few more pro-social tendencies. This trend coincides with the increasingly inter-dependent nature of society, which itself is caused largely by urbanization.
Taking the concept further, this trend towards pro-social behavior extends into multiple fields. Assassination as a tool for advancement or threat-elimination, for instance, has been reduced to simple character assassination; even that is increasingly frowned upon (impacting voter turnout, which further weakens the system that fosters it). Altruism is increasingly seen as good business rather than simply a series of charitable acts. Diversity is less a threat to be stigmatized and more an opportunity to be harnessed.
Two key factors that don’t get enough consideration in this field, largely because it’s a field few have explored; healthcare/quality-of-life and genetics. Thanks to greater knowledge and management of human biology and kinetics, we are able to live a lot longer; those who would die or be ill can be productive members of society, even passing along their genes. We want to look after ourselves, therefore our own families, etc., but the complex and costly nature of healthcare requires shared social costs and collaboration. This inevitably leads to selfishly supporting otherwise-disenfranchised folk to benefit from them. In terms of genetics, the traits that are desirable in an urban mate are rather different than those deemed essential in a rural context. In a city, the ability to work a room is a better indicator of future success than the ability to swing an axe or grow potatoes.
The broad, historical trend is away from all forms of anti-social behavioural patterns and towards pro-social, adaptive ones. Our biological and genetic realities explain why this is the case.
There is just cause for rational optimism, after all.