Human Biology 101: 1st Grader Edition

A couple of weeks ago I took my first graders outside for art. We were engaged in a drawing scavenger hunt. The students were tasked with drawing any natural things that they could find. The following conversation took place between me, an intellectually advanced first grader, and a, um, not-so intellectually advanced first grader (but an oh-so, gosh-darn cute one):

FG1: "Are humans natural?"
Me: "Well, we're not man-made, are we?"
FG1 (an intense look of deep thought overtakes his face): Um.....
Me (cutting him off before he could counter that, yes, in fact, one could argue that humans are technically man-made): "Okay, well, it doesn't require any tools or machines to make us, right?"
FG1: "No."
Me: "Well, then humans are natural!"
FG2: "But, tools are used."
Me: "They are?"
FG2: "Yeah. You need a knife to cut the girl's stomach open to get the baby out."

And with that I chose to exit the conversation and walk away. I didn't really see it as my place to get into the birth of babies with a couple of first graders.