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The irreversible global catastrophe is imperialist militaries massacring people with little risk to themselves. 
The irreversible global catastrophe is assembly line robots at the Toyota plant becoming sentient and going on a freaking epic terminator style mass shooting and enslave everyone except me 
Enough said about treating aggregate language models as "AI", I've got my own special grievance with this
"human beings dominate other species because the human brain possessed distinctive capabilities other animals lack" Shitty way to understand human success. It's from our ability to act as a group, we could be dumb as shit and if we were still altruistic we'd remain successful, it's nature's cheat code
Anthropologists say prehistoric human skeletal remains with mended leg bones are one of the earliest signs of human civilization.
In almost all animals, even herd species, a broken limb is essentially a death sentence because they can't get to food and water, or escape from predators or find shelter. Even a solitary person in the modern day can't survive for very long if they can't find help.
The fact that ancient human remains have been found with mended bones means that the person had help immobilizing their broken leg, and were protected and fed while it healed.
Matabele ants have been observed picking up and carrying nest mates who emit a specific pheromone that signals to others that they have been wounded. Back at the nest, others lick the injured ant's wounds and it decreases overall mortality by like 30 percent iirc.
(My favorite element of this behavior is that some ants have also been observed "faking" their wound signal to get carried back, though it's hard to say whether this is intentional. Other injured ants will even fight off their would-be rescuers if they are so wounded that they will not recover.)
Lol I know right, what a sharp little nugget of drama hidden away in such a small society
It's a nice, feel good story, oft repeated on the internet, but the evidence is dubious.
"Anthropologists" would more accurately refer specifically to Margaret Mead, a well known anthropologist. But even then, evidence of her saying it is only secondhand. When later asked in an interview, she gave a very different answer, listing things like elaborate division of labour, record keeping, and such.
But also, animals have been spotted giving basic medical care to each other in the wild. However, I could not find anything that specifically shows animals giving medical care at their own detriment to an individual who would be doomed without it.
And my own two cents: Quadrupeds can survive with a missing limb. Perhaps not as well as an unscathed individual, but still, the focus on the femur is human centric for this reason. So if anything, I think the story should ask, "How do we know when human society started?"