This activity guides the analysis of a published scientific figure from the world’s longest-running controlled artificial selection study, in which scientists tested whether they could use selective breeding to change the protein concentration of maize (corn).

The study began in 1896 and spans over 100 generations of maize. Each generation, scientists planted seeds from the most protein-rich and protein-deficient plants from the previous generation. The figure shows the protein content in each generation for the Illinois High Protein (IHP) and the Illinois Low Protein (ILP) strains. In generation 48, scientists reversed the direction of selection on some of the IHP and ILP plants, leading to the new strains RHP and RLP. In generation 90, scientists reversed the direction of selection on some of the ILP plants again, producing the new strain RLP2.

The “Educator Materials” document includes a captioned figure, background information, graph interpretation, and discussion questions. The “Student Handout” includes a captioned figure and background information. The original article is also provided as a download.