Motion Sickness Difficult To Explain In Terms Of Evolution

Motion sickness has been called an evolutionary anomaly because it seems highly disadvantageous to those who suffer from it. Yet, motion sickness occurs in many species. Why should it have evolved at all? Recognizing this problem, Michel Treisman seeks to explain the anomaly by noting that neurotoxins accidently ingested by animals cause essentially the same symptoms as motion sickness. To survive, animals must eliminate ingested neurotoxins by vomiting or defecation, both of which also accompany motion sickness. It is simply coincidental that modern vehicles duplicate these symptoms through their motions. The body interprets the signals created by motion as due to dangerous ingested material and acts accordingly.

(Treisman, Michel; "Motion Sickness: An Evolutionary Hypothesis," Science, 197:493, 1977.)