Ming’s Wisdom

It’s always been a mystery to me why some of us get sick easily when riding in cars, boats, or roller coasters, while the rest enjoy those stomach-churning motions without any ill symptoms. A couple months ago I finally figured it out.

I was watching a Discovery documentary on the evolution of ancient sea creatures from several hundred million years ago, and the realization hit me during the narration of how certain animals in the ocean have their closest living relatives being a species that lives on land. They key fact I learned was that the sensitivity of the inner ear (which helps animals balance), is gradually changed as a species moves into the ocean or onto land. Species that live on land require a sensitive inner ear for good balance and always keeping their head up. An example of when this comes into use is when you roll off your bike, and you are able to keep your head up to avoid injury of hitting it on the ground. However, for a species that lives in the ocean, this is not needed as much, but an inner ear that is too sensitive could overload due to the 3-dimensional freedom involved in living underwater.

The next piece of the puzzle is solved by the principle of evolution. Those animals that have a more sensitive inner ear will be less likely to hurt their head during a fall on land. Those animals that have a less sensitive inner ear will be more likely to have more agile movements in water without getting nauseated. In the history of the earth, some species have undergone a move from land to water or water to land, and over the next few million years their inner ears have evolved to increase or decrease in sensitivity to adjust to their new environment.

By this logic, humans, as land animals, should on average have fairly sensitive inner ears, at least in comparison to ocean creatures, and all get car sickness. But why then do some people get nauseated in cars and some don’t? The answer to this question lies in what if the earth floods and we as a species move to the ocean over the next several million years. Nature has provided us with natural variation (due to sexual reproduction), so that a whole range of sensitivity occurs in different people’s inner ears. In case we stay on land, those with sensitive inner ears will carry on the species, and in case we are pushed to the ocean, the ones with less sensitive inner ears could survive. This gives us as a species the ability to survive in a changing environment (and potentially one day become like the dolphins, whales, and sea lions, if that’s the direction we need to go to survive). So now you know why you have car sickness, and your buddy doesn’t. The two of you join forces together to carry on the survival of our species.

This entry was posted on Tuesday, November 24th, 2009 at 19:26 and is filed under Earth. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.