Homo sapiens
Harari's central thesis is that Homo sapiens were successful only because they were able to cooperate in large groups. However, despite this ability, ironically humans remain fractured. They oftentimes isolate themselves by things like religion and the country they live in, showing that humanity's ability for cooperation isn't everything.
Megafuana
Harari hypothesizes that Homo sapiens killed megafauna (or big animals, like the woolly mammoth). He also says that humans kill animals that are useful to them or dangerous. Ironically, they still killed some megafauna who were neither dangerous nor useful, suggesting a deeper motivation.
The Industrial Revolution
With advancements like the Industrial Revolution, humans on the surface became more civilized and technologically advanced. However, in many ways, this advancement did the opposite: it enslaved people, chaining them to one location, and made them less civilized.
AI
In an effort to create new, human-like life, Homo sapiens have ignored what exactly it means to be human and has ironically embued their creations with a sense of artificiality. This goes against their stated intention and shows the irony of human intentions.
