Textbooks as a Possible Influence on Unscientific Ideas about Evolution

While school textbooks are assumed to be written for and used by students, it is widely acknowledged that they also serve a vital support function for teachers, particularly in times of curriculum change. A basic assumption is that biology textbooks are scientifically accurate. Furthermore, because of the negative impact of ‘misconceptions’ on learning, it is desirable that textbooks point out common misconceptions and why they are scientifically unacceptable. This paper reports on a study of life sciences textbooks as a potential influence on misconceptions about evolution by natural selection. Textbooks for Grades 10 to 12, from two different publishers, were investigated using content analysis to establish, first, the nature and extent of scientifically incorrect statements about evolution; second, latent problems with wording which might lead to unscientific ideas; and third, whether the books identified and addressed common misconceptions. Unscientific statements were found in all six books, but latent problems associated with the way explanations were expressed were also considered to pose a significant threat to learning. While particularly important for textbook authors and publishers, these findings are also of value to teachers. Although this study was conducted in South Africa, the findings provide useful insights for a wider audience of biology education stakeholders.     

Evolution in Lego ®: A Physical Simulation of Adaptation by Natural Selection

We describe a physical simulation of natural selection in a population of legorgs, six-segment model organisms. Legorg morphology is genetically specified by five alleles on each segment. Legorgs show a simple form of motility that could evolve in originally sessile animals. This motility, the ability to move horizontally on a smooth surface, depends on the morphology and interaction of the six segments that produce different patterns of locomotion. Legorgs are selected for motility and reproduce in proportion to fitness. After just five generations, the average population motility increases 2.5 times. Additionally, we describe a slightly less time-consuming simulation of legorg evolution, where fitness is assigned by comparison with a template. The calculation of gene pools is precisely the same as in the previous simulation and produces very robust increases in fitness during five generations. The simulation is designed as a classroom experiment to explore the mechanism of natural selection. A test of its learning efficiency by evaluating the students’ conception of central aspects of evolutionary theory before and after showed a significant improvement. The surprising power of natural selection in this very simple physical system may also be exploited in more advanced experiments.