The Doctor caught himself, and then found he suddenly had Alan on top of him. Well, that was a bit awkward. He shoved off the ground, helping to haul the other man up.

"Something's happening here," he snapped, suddenly angry. "Something's affecting the native species of this planet, and you're arguing with me about who I'm blaming in this?"

Because it was more than just who Luke was blaming, or who they were blaming. The Doctor blamed himself.