Volume 96, Issue 75
Thursday, February 12, 2003

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You can thank evolution for hiccups and opposable thumbs

By Des Stutchbury
Gazette Staff

Sigultus is not a rare STD; it's that socially embarrassing bodily function, the dreaded hiccup.

A new theory regarding the source of the hiccup was published in the journal BioEssays in February. The article, entitled "A phylogenic hypothesis for the origin of hiccough," discusses the development of the hiccup as an evolutionary process.

"What we see in the tadpole can be applied to human respiratory research," said Kosta Vasilakos, a member of a respiratory research group in the faculty of medicine at the University of Calgary and co-author of the study.

"The hiccup is a curiosity and possibly an example of a pattern in humans [with] an ancestral source," Vasilakos said.

Vasilakos said his theory is a phylogenetic hypothesis which supports evolutionary theory, explaining that, when amphibians moved from water to land, the hiccup developed as a means to keep water out of their lungs.

During the evolutionary process, a method that effectively protected the lungs was advantageous to evolving amphibians, he explained, noting the hiccup functions in this capacity.

"A hiccup is a involuntary contraction of the respiratory muscles that cause you to inhale," explained Tom Stavraky, a Western professor in the department of physiology and pharmacology.

"The diaphragm contracts and draws air in," Stavraky said. "The glottis, located in the throat, closes near the end of the hiccup event and prevents anything [from] entering the lungs."

Cures for hiccups are numerous, Stavraky said, noting one common method is to breathe into a paper bag in the belief that increased carbon dioxide will inhibit the hiccup reflex. However, Stavraky recommends slow deep breaths to alleviate hiccups.

According to an article written by Garry Wilkes, director of emergency medicine and clinical senior lecturer at the University of Queensland in Australia, hiccups can be a serious health hazard and can even cause death.

Stated in Wilke's article, a hiccup bout is any episode lasting more than a few minutes. After 48 hours, hiccups are classified as persistent or protracted and beyond one month, they are considered intractable, the article states.


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