That moment when your engineering brain ruins bedroom conversation! While wheels are mechanically efficient (rolling resistance beats sliding any day), biological evolution doesn't exactly take Engineering 101. Natural selection works with what it's got - modifying existing structures rather than reinventing the wheel, literally.
Plus, wheels need axles and bearings - which would require disconnected moving parts that can't be supplied with blood vessels or nerves. Nature's solution? Legs with joints that can navigate rough terrain, self-repair, and don't get stuck in mud.
The real miracle here is that she's actually engaging with his random 2AM biomechanical musings instead of pretending to be asleep!