The story of Grandmother Fish is simplified for preschoolers, so the science notes for parents in the back have to be rigorous. Fortunately, I’m getting help from the National Center for Science Education. These people are serious about teaching evolution and climate change. Eric Meikle is helping me personally, and he recently gave me a welcome point-by-point critique of my endnotes. The next version of the draft will include updated information thanks to him. He and I spent extra time trying to get the paragraph below just right. This is the paragraph in the back that helps parents talk to their children about the “grab” motion that Grandmother Ape was good at. Talking about “feet” and “hands” gets tricky when you’re talking about primates, humans in particular. Our ancestors’ limbs have been specialized first for swimming, then crawling, and then climbing. Now our hind limbs are specialized for walking while our forelimbs are specialized for grabbing. It might sound minor, but I want to help children understand how special human feet are. Here’s the paragraph that Eric and I worked out.

Our early primate ancestors’ paws evolved into four “hands” that helped them climb and live in trees. In humans, our rear “hands” have evolved into stable feet specialized for walking and running on the ground. They are a new kind of foot, unlike the feet of any other animal.

Lamarck is famous for being wrong about how evolution worked, but he was right about one thing: humans evolved from “four-handed” animals. Two hundred years ago, his contemporaries jeered at him for his bold claim, but today it’s time for preschoolers to learn that he was right all along.

—Jonathan