Caleb (6): "Mommy, why does the cat always rip apart the couch like that?"
Me (43): "That's how he sharpens his claws."
Caleb: "Why does he need to sharpen his claws?"
Me (seeing an opportunity to wrangle the conversation over to evolution): "Well, why do you think?"
Caleb: "Because cats are hunters? They can get more mice with sharp claws?"
Me: "Right! And what can the cats who get more mice do?"
Caleb (sensing that Mommy is off on her whole Darwin kick again): "Ummm... natural selection!?"
Me: "Well, sort of, but how would that work? If you're a cat whose belly is always full and you feel good, do you think you'd live longer or shorter than another cat who can't really catch mice?"
Caleb: "Longer, yeah! The ones with sharp claws are awesome!"
Me: "And then if you're living longer and healthier, what might you be able to do?"
Caleb: (Stultified expression)
Izzy (9, eavesdropping): "You have kittens, Caleb! And the kittens have sharp claws just like you do! And then they can get more mice and be healthier."
Me: "Right, and it all leads to us having a shredded couch."