Are They Cousins? Exploring University Students’ Acceptance of Common Ancestry in Evolution

Efforts to measure student acceptance of evolution have led to the development of several surveys. One persistent challenge has been constructing a survey that accurately characterizes not only students who accept or reject evolution in its entirety, but also those who accept only certain aspects. This study sought to inform these efforts by exploring how students delineate between what they perceive as acceptable versus unacceptable claims of shared ancestry. We conducted semistructured interviews with U.S. university students in which participants were shown pairs of organisms, asked to explain whether they think the two shared a common ancestor, and explain why or why not. We found that 1) most participants accepted common ancestry for closely related species but rejected it for distantly related species, 2) participants frequently rejected common ancestry between terrestrial and aquatic species, citing habitat differences, 3) participants who rejected common ancestry between humans and chimpanzees often expressed acceptance of human microevolution, and 4) participants who later claimed no creationist beliefs displayed views on evolution similar to those of self-described creationists. These findings can inform ongoing efforts to improve the measurement of student evolution acceptance, particularly those measuring both conceptual knowledge and personal assent.