Find News and Events


AZ: Evidence of Appendix Evolution in MWU-Led Study Changes Long-Held Assumptions

February 18, 2013

by Office of Communications

Heather F. Smith, Ph.D.A human organ long considered dispensable may have a more important function than we realize, according to new research published by an international team led by a Midwestern University faculty member.

Heather F. Smith, Ph.D., Assistant Professor of Anatomy at the Arizona College of Osteopathic Medicine, is the lead author of a groundbreaking and extensive study on the human appendix which has the scientific community buzzing. The study indicates that the appendix has evolved at least 32 times in mammals, which suggests that the appendix is an adaptive and not vestigial structure.

Charles Darwin hypothesized that ape appendixes are a result of the species transitioning from eating vegetation to eating fruit. But while the study found support for this hypothesis in apes, the evidence did not correlate in other mammals. The presence of multiple varied evolutionary paths of the appendix in disparate animals indicates that the organ provides advantageous function. What that function may be is still not definitive, but previous studies have theorized that the appendix might be a "safe house" for beneficial bacteria found in the digestive tract in times of high immune activity and illness.

Researchers collaborating with Dr. Smith on the study are William Parker, Ph.D., Immunologist, Department of Surgery, Duke Medical Center, Durham, North Carolina; Sanet H. Kotzé, Ph.D., Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, University of Stellenbosch, Tygerberg, South Africa; and Michel Laurin, Ph.D.,  from the Muséum National d'Histoire Naturelle in France. Midwestern University Research Associate Brent Adrian also contributed original illustrations for the study.

Study Cited:
Smith H.F., Parker W., Kotze S., Laurin M. (in press). "Comptes Rendus Palevol: Multiple independent appearances of the cecal appendix in mammalian evolution and an investigation of related ecological and anatomical factors."

More Information

For more information, please contact:
Office of Communications
630.515.7333 (IL) or 623.572.3353 (AZ)