Like this:

I know I came from you and mommy, and that you came from your mommy and daddy, and that grandma and grandpa came from their mommies and daddies, but where did the first kids come from?

That was the four-year-old daughter of the creator of Calamities of Nature, a webcomic with a strong science component. What would you tell a four-year-old?

I think I would have struggled with this question but, now that I know, I would tell a four-year-old exactly what this kid’s parent told her:

I explained to her as best I could that when kids are born they are slightly different from their parents, and over very, very long lengths time these small changes can add up to be big changes. A very, very long time ago, people weren’t people like they are now, but instead more like apes and monkeys. Depending on where these ancestors lived, they changed differently over time, and some became people while others became chimpanzees (which we had recently seen at the zoo).

If someone told me this when I was four my mind would be blown. It would definitely have been the coolest thing I had ever heard in my four years of life. I don’t think I could have come up with something this crazy on my own and yet adults are telling me this amazing story that I’m related to the chimps we see at the zoo.

It crossed my mind when I was thinking about what to tell a four-year-old about evolution that maybe they’re too young to get it. Wrong again. Check out what this kid drew later that day:

A monkey turning into a person. I will never sell a four-year-old short again.