Tuesday, December 8, 2009

Can kids tell earthworms apart?

Here's how it went with Caleb (5) and me (42).

Me: Hey, Caleb, I have a question for you. Let's say there's a bunch of giraffes, grownup giraffes, some boys and some girls. Do you think those giraffes are different from each other?

Caleb: Yeah, they're different.

Me: Really? How?

Caleb: Their spots, they have different spots. And their necks too! Some are longer than others. Oh, and their personalities.

Me: Hmmm, cool. What about earthworms? Remember those earthworms we dug up last summer? Do you think they're different from each other?

Caleb: Nope. They're all exactly the same.

Poor earthworms. In Caleb's world they just don't vary at all. That's gotta hurt, especially when you're trying to evolve to adapt to changing conditions.

After reading this psychological research recently, I've been thinking about whether kids *get* variation within species. It's so important to understanding evolution later, but I guess kids naturally think of animals as having specific traits that can't vary. All lions roar in just the same way, all mice have the same whiskers, and if you mess with that, well, you're not talking about lions or mice anymore, Mom.

(Nerd Note: In other words, our brains default to the essentialist view. It's a terrific advantage for language development, but a terrific roadblock to understanding "species" as a probabilistic concept.)

So my new kick is: Let's point out variation within species to kids. It's amazing how often it comes up now that it's on my mind. Just today, the centerpiece of our cafe table was several bamboo shoots in a vase. How different each shoot was from the others, when we looked closely! And then we had some cookies.

So my little interview with Caleb gave me hope. Those giraffes vary, hooray! I have a hunch that variability is easier for kids to get the closer they feel to a species. I bet any kid with a dog or cat can name precisely how their pet is different from any other member of the same breed. But when it comes to earthworms, well, they're just weird. And exactly the same as each other, apparently.

If you talk to your kid about variation, let us know how it goes.


  1. Two thoughts. Kids are amazingly good at telling whether cookies or dessert portions differ. Probably down to microgram-order differences. And if you showed them a bunch of kids, I also think they would verbalize differences immediately, and at a very young age. So I wonder why they don't transfer that ability to their views of earthworms? Might be a fun activity for teachers to have 50 different bean seed types (all the same species), and ask students which ones they'd like to grow. Would demonstrate parental transmission of coat phenotype (probably, or at least in many cases). Would also demonstrate seed variation within a species. And if they had races of the beans up a pole, you might be able to work in fitness in some way (or count the number of pods they make). Would be great fun, too.

  2. By the way, here's a photograph of an earthworm your kids might enjoy:


  3. Thanks, Colin! I agree about the cookies, good point. The bean activity is a good idea -- especially if they are all within the same species. Heck, I might do it myself with the kids here at home. (PS. That earthworm is just waaaaaay too long. There oughtta be a law.)