I have the opinion that humanity has not grown up at all, for the entire time of recorded history. From the most simple and humble person to the most powerful one we still behave as we did when we started recording history. The only real change has been technological. Humanity as a whole is unable to plan for the future. If we know there won't be water in a certain region in 50 years, for instance, we are unable to plan and act NOW to avoid it.
When the meteor that will extinguish humanity finally arrives, we'll still be discussing what to do and what the costs to do it are and who will pay while it enters our atmosphere...
"The forest was shrinking but the trees kept voting for the axe for the axe was clever and convinced the trees that because his handle was made of wood he was one of them"