Can What Makes a Lion Roar Help Human With a Weak Voice?

Researchers in Iowa have discovered what makes a lion or tiger roar so effectively. Apparently, there is a layer of fat within large feline vocal cords that makes the vocal cords especially prone to vibrate easily with minimal exhalation effort.

What import does this have to humans?

Well, there are patients who have a very weak voice due to vocal cord atrophy as well as vocal cord paralysis. Standard interventions include voice therapy as well as surgical procedures using an implant or injectable material in order to "bulk" up the vocal cord.

In fact... one such injectable material that has been used to inject into vocal cords is fat, typically taken from the belly of the patient!

Two points to keep in mind however...

Just like in lions and tigers, it DOES improve the vocal strength and volume to a patient who previously had a weak voice, may now have a much stronger voice after the procedure.

However, the second point is that by making the vocal cord "bulkier" you are making it thicker which can decrease the vocal pitch... just like a violin string where the thicker the string, the lower the pitch.

On another related note... human infants have fat within their vocal cords... that may be why something so small with tiny lungs can produce such a terrific loud cry!

Read a story in the NYT regarding this research here.

Reference:
Adapted to Roar: Functional Morphology of Tiger and Lion Vocal Folds. PLoS ONE 6(11): e27029. doi:10.1371/journal.pone.0027029

Shape of Human Nose Influenced by Climate

The basic function of the human nose is to warm and humidify the air before it reaches the lungs. Because of the wide variation of human habitats from the polar cold and dry air to the equatorial hot and humid weather, one would expect the nose to accommodate to these climate extremes accordingly thru evolutionary pressures.

In essence, logically one would expect the nose to change shape to enhance time that air is in contact with the warm and moist nasal interior in cold and dry climates compared to the opposite environmental extreme.

German scientists evaluated this hypothesis thru 3D modeling of 100 skulls to analyze the shape of the bony nasal cavity of 10 modern human groups living in five different climates and found that the bony nasal cavity appears mostly associated with temperature effects and the nasopharynx with humidity.

Humans living in cold, dry climates tended to have nasal cavities relatively high and long with an abrupt narrowing in the upper nasal cavity than those living in hot, humid climates. Such characteristics enhance contact between the air and the nasal mucosal tissue that helps to warm and humidify that air.

What does such a nose look from the outside? A narrow, longer internal nasal cavity is generally linked to a relatively narrower and more projected nose.

Read a magazine article about this research.

Reference:
Climate-related variation of the human nasal cavity. American Journal of Physical Anthropology
Volume 145, Issue 4, pages 599–614, August 2011

Link Between Oral Sex and Head & Neck Cancer

USA Today published a pretty accurate article regarding the rise of certain head & neck cancers with the increased popularity of oral sex and number of sexual partners.

The factor that creates this link is the HPV virus which is associated with tonsil and tongue cancer. Alcohol and tobacco use is more highly linked with such oral cancers, but HPV does appear to be an independent risk factor.

A 2007 study in the New England Journal of Medicine found that younger people with head and neck cancers who tested positive for oral HPV infection were more likely to have had multiple vaginal and oral sex partners in their lifetime. Having six or more oral sex partners over a lifetime was associated with a 3.4 times higher risk for oropharyngeal cancer; cancers of the base of the tongue, back of the throat, or tonsils. Having 26 or more vaginal-sex partners tripled the risk. The association continued to increase as the number of partners in either category increased.

Of greater concern is that "French" kissing may also potentially be a mode of transmission.

The good news (if one is a young, non-smoker diagnosed with HPV-positive tumors) is that about 85% of non-smoking people with HPV-positive tumors survive. That number drops to 45 or 50% in people who smoke and are HPV-negative.

Th take-home message here is that even if you are a non-smoker and non-drinker, you can STILL develop head and neck cancer. Oral HPV infection is strongly associated with oropharyngeal cancer among subjects with or without the established risk factors of tobacco and alcohol use and that oral HPV infection can occur through sexual activity.

Furthermore, it is possible that the HPV vaccine (ie, gardasil) may also be protective (studies pending) for both women AND men.

Read the USA Today article here.

References:
Human papillomavirus and oropharyngeal cancer. N Engl J Med. 2007 Sep 13;357(11):1157; author reply 1157-8

Human papillomaviruses in head and neck carcinomas. N Engl J Med. 2007 May 10;356(19):1993-5.

Case-control study of human papillomavirus and oropharyngeal cancer. N Engl J Med. 2007 May 10;356(19):1944-56.