It’s not a straightforward answer. Sometimes a trait that we think is unique in humans is disputed when we find evidence of it in animals. We could say it’s caring for each other or empathy but these do appear in certain non human species so they’re not unique to us. We find this to be true, more and more often.
Check out this interview by James Nestor as he talks about the astonishing behavior of sperm whales. The size and composition of their brains may indicate a very high level of intelligence that we still have lots to learn about.
Or this article from BBC Future a few years back that talks about this very issue.
When you pull together our unparalleled language skills, our ability to infer others’ mental states and our instinct for cooperation, you have something unprecedented. Us.
Culture, morality, art, helpfulness, many of these things have been discovered outside the human world and it may be that these exist at different levels in all living animals – just more pronounced in humans. What do you reckon is the most human trait and why? Perhaps it’s something not so positive that unfortunately arises in humans. After all humans have a great capacity for good and bad.