[gozur88]

It doesn't necessarily have to be altruism to make sense. Less for orcas to eat --> fewer orcas --> fewer attacks on humpback calves.

[buserror]

Or perhaps it makes sense to practice the skill as much as they can, so they are better at it when it comes to defend their own young?

[MrMullen]

To me, this is what it is. If young Humpbacks are vulnerable for a certain amount of time, being good at protecting them would a good idea. They can't risk losing that skill since every time they fail, a young Humpback dies.

[allendoerfer]

If the possess that level of intelligence, we will probably someday find a way to ask them.

[Aelinsaar]

That would be quite the impressive bit of generalized cognition and logic from a whale, perhaps even more significant than feeling something.

[Kapow]

It wouldn't need to involve cognition and logic, it could be evolutionary coincidence: humpback whales with behavior that happens to result in fewer orcas nearby would have more surviving offspring, so this behavior would be selected for.

[Aelinsaar]

Right, right, I missed that completely, damn!