Emotion and instinct
Various variables distinguish compassionate and altruistic acts, according to marine scientist Robert Pitmas.
Humans frequently protect animals from harm out of compassion, but other animals’ altruistic behavior can have other motivations.
It’s possible that the humpback acted out of compassion to protect Nan, but it’s more likely that its actions were motivated by a desire to protect its children, which Nan had reminded him of.
But, as we’ll see shortly, blaming everything on instinct is tricky.