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Monday, March 24, 2014

Young children can understand natural selection

Suppose you read a picture book about some mythical trunked mammals called ‘pilosas’. The pilosas are evenly divided between those with skinny trunks and those with fat trunks, and their diet consists of insects. However, the climate where the pilosas live changes so that insects move deep underground where only thin-trunked pilosas can reach them. After some time, there are very few fat-trunked pilosas around, virtually all the pilosas now have thin trunks.

What would you conclude from reading that story? If you are a 5 to 8 year old child, you would come away with a pretty good understand of natural selection.

Researchers led by Deborah Kelemen of Boston University assessed how well 28 five and six year olds and 33 seven and eight year olds understood evolution by natural selection on a scale of zero to four. The children were then given (or read to from) the pilosa picture book and retested. Only if the kids understood that individual pilosas were not changing, but rather that the makeup of the population of pilosas was changing because some groups were out-reproducing others were they given full points for understanding natural selection.

The results are below. The top panel is for the five and six year old kids, the bottom for the 7 and 8 year olds. As you can see, before the picture book (pretest), the younger kids had almost no familiarity with the concept of natural selection. Afterwards, most of them had at least some understanding and nearly a fifth of them could apply the concept to new populations of animals (generalization test). For the older kids, the results were even more impressive. Nearly all of them came away with a very good idea of natural selection works.

Fig. 2.
(a) younger and (b) older children classified into the five levels of natural-selection understanding as a function of assessment. Because of rounding, percentages do not always add up to 100. Level 0 = no isolated facts; Level 1 = isolated facts but no natural-selection understanding; Level 2 = foundation for natural-selection understanding; Level 3 = natural-selection understanding in one generation; Level 4 = natural-selection understanding for multiple generations.
Psychological science PMID: 24503874.

This is significant because natural selection is not usually taught before age 13, and often not until 18, if at all. By that time, incorrect ideas can become entrenched in students’ minds. It was thought that children wouldn’t be able to understand complex ideas like natural selection until they were in their teens. Not so much.

As Kelemen explains:

It turns out that if you put the facts into the context of a theory, the kids learn not only the facts, but they also understand the full explanation. And they get it beyond a level we ever imagined they would, given how young they are. 

Kelemen D, Emmons NA, Seston Schillaci R, & Ganea PA (2014). Young Children Can Be Taught Basic Natural Selection Using a Picture-Storybook Intervention. Psychological science PMID: 24503874.