Petite, bulbous, hooked, up-turned, sharp, wide, or prominent, people attribute the shapes and distinctive characteristics of their noses to a parent or grandparent through the study of genetics. But did you know that the unique shape actually formed as a result of evolutionary adaptation? According to an article published in the Journals of PLOS Genetics, nose shape among populations are not simply the result of genetic drift, but may be adaptations to climate.
Rather than focusing on the variations in height, skin color or hair color throughout the world, global researchers led by a team at the Department of Anthropology at Penn State University, took into consideration a variety of nasal differences, such as nasal, height, ridge length and tip protrusion of 476 subjects who have ancestry in Africa, Asia, and Europe. According to Dr. Mark D. Shriver, Professor of Biological Anthropology, “We focused on nose traits that differ across populations and looked at geographical variation with respect to temperature and humidity.” His team concluded that the width of the nostrils and the base of the nose measurements differed across populations more than could be accounted for by “genetic drift” — indicating an act of natural selection in the evolution of human nose shapes.
Analyzed, it appears that wider noses are more common in warm and humid climates than narrower one, which are typically found in cold and dry environments. “Out of all the aspects of nose shape that we studied, only the width of the nose stands out as being more different across populations than expected by chance,” shares Arslan Zaidi, the study’s co-author, with The Daily Mail. “Most of the genetic and phenotypic variation among humans exists within populations, not between them.”
Have you ever encountered tooth sensitivity after eating a chocolate bar, licking an ice cream cone, or biting down into a crunchy apple? Tooth sensitivity affects approximately one out of every eight adults, according to a survey in HealthDay News. The study reported that sensitive teeth were most common in young adults, women and people who had receding gums or did at-home tooth whitening. We turned to Beverly Hills restorative dentist, Dr. Gaby Cosgrove, to get to the root of the problem!
Causes of Tooth Sensitivity
According to Dr. Cosgrove, tooth sensitivity can present as a result of tooth decay, fracture, and enamel sensitivity. Tooth decay occurs when bacteria breaks down the tooth’s protective surface, leaving exposed areas vulnerable to sensitivity. Fractures, caused by weakened fillings and restorations (often by age) or from excessive nighttime tooth grinding, can cause bite/pressure sensitivity. Excessive enamel wear from tooth grinding, acid reflux, or recession of the gums exposes the roots at the gum line, thus causing sensitivity. “Once the hard enamel coating of the tooth is worn through, the dentinal tubules communicate and are closer to the nerve of the tooth,” shares Dr. Cosgrove. “That’s why the teeth feel so sensitive to touch and cold.”
Ways To Combat Sensitivity
“The best way to combat root surface sensitivity is by using a toothpaste like Sensodyne with active ingredient potassium nitrate to seal dentinal tubules,” shares Dr. Cosgrove. To manage discomfort, over-the-counter, topical dental desensitizers can be applied to root surfaces or in a bleaching tray appliance. “Some people benefit from using prescription strength Fluoride based tooth pastes at night only,” she offers. “Dentist and hygienists can also apply fluoride varnish after a teeth-cleaning to seal dentinal tubules.” Read more of this story »