For all our desire to find shared attributes with the animal world, it would seem most of the links we make are projections. See a video of two sea otters holding hands, and call it true love.
According to recent research, as profiled in this week's TIME magazine cover story
, one thing humans really do share with animals is the ability to form enduring friendships.
"Animal friendship is about enduring bonds defined by sharing, sacrificing, and when circumstances warrant it, grieving," writes Carl Zimmer. "Not all animal friendships exhibit all those behaviors, but they exhibit enough of them – with enough consistency – that something deep is clearly going on."
Insights into animal friendships come from varying species. Primatologists found, in years of field research, that different unrelated female baboons would form strong relationships that lasted for years. Male dolphins, meanwhile, would form friendships when they were young and maintain them over time.
One surprising finding is that dogs are not as high on the friendship scale as other animals. While they may prefer the company of certain dogs over others, the relationships "fall well short of true friendship" – even the ones they share with us.
The research on animal friendships could at some point provide clues as to how friendships benefit human health, showing, for example, how social connections lower stress and blood pressure, and boost immunity.
For more on the science of animal friendships, pick up this week's issue of TIME, on newsstands now.