VARIATION IN BELIEFS HELD ABOUT THE NUMBER AND CAUSES OF MASS EXTINCTIONS BETWEEN SCIENCE AND NON-SCIENCE MAJORS

Students have a wide range of beliefs concerning mass extinctions beginning with how many occurred over geologic time and causes of such events. Over five semesters, we gave an open-ended questionnaire to 101 students taking an introductory Earth history course. We also administered the same questions to 28 students taking an introductory art course. The Earth history course was required for students majoring in Biology and Earth or Environmental Science including students majoring in secondary science teaching, whereas the art course provided a comparison point between science and non-science students. The questions probed student beliefs about mass extinctions including how many have occurred and their causes.

The science majors held different beliefs than the non-science majors in some, but not all, questions. When asked how many mass extinctions have occurred, 13% of all students surveyed said only one mass extinction has taken place but this number varied depending on the type of major (34% of the non-science majors vs 6% of the science majors). Conversely, 34% of the science majors stated that Earth has experienced 5 or 6 extinctions, but 0% of the non-science majors gave this response. In addition, 8 students thought that the Earth has experienced over 100 mass extinctions and 21 gave vague responses such as “many”. When asked what causes mass extinctions, 54% of all the participants cited changes in either the climate or atmospheric composition (40% non-science majors vs 59% science majors). Similarly, 35% of all participants (25% non-science vs 39%) stated that mass extinctions are caused by impacts of extra-terrestrial objects. Other causes included natural disasters, disease, famine, predation, or humans.

These data suggest that both science and non-science majors hold inaccurate views regarding mass extinctions including the number of events and causes. While many students correctly identified climate change or asteroid impacts as main extinction drivers, others cited more generic causes that described extinction at the species or regional level. This is likely a consequence of having a large number of biology majors taking Earth history.