Don't pat yourself on the back for holding that door open for a stranger just yet. We may call it human decency, but it’s not just humans who have it.

"We're trying to understand what's similar to humans, what's different to humans," says Jingzhi Tan, a co-author on the study.

The researchers knew that bonobos would share food with strangers, and they wanted to see whether the apes would also help a stranger without getting any reward themselves.

With apes from the Lola ya Bonobo sanctuary in the Democratic Republic of Congo, the researchers placed pairs of bonobos that didn’t know one another in adjacent rooms separated by a fence and hoisted a piece of an apple over one