Translational Research in Anatomy (Sep 2021)
Hypothesis about the appearance of the vermillion border of the lips in Homo sapiens
Abstract
The vermillion border of the lips is an exclusive aspect of Homo sapiens, and is one of the few morphological elements that mark the facial difference with the rest of hominids. On the other hand, modern spoken language is also a characteristic of the human species. Spoken language and the vermillion border could have a relationship. Hypothesis: About 200,000 years ago, spoken language appeared in Africa. The friction between the lips when pronouncing bilabial syllables could have been the origin of the disappearance of hair follicles, resulting in the emergence of the vermillion border of the lips. This study tries to evaluate the influence of persistent, non-aggressive friction on the density of the hair follicles in a given area of human skin. Material and methods: Twenty-five men between the ages of 25 and 95 years old, who had worn a gold ring on the finger of one hand for more than 5 years, were selected. A trichogram of the skin of the finger with the ring was made and compared with the skin of the finger without a ring on the opposite hand. The data analysis was carried out with the SPSS version 18 statistical package and the Kolmogorov-Smirnov, Student T, Mann Witney's U and Spearman tests were used. Results: The area of the collective study of fingers with a ring gave an average number of hair follicles of 7.0 with a standard deviation of 2.80. The area of the collective control fingers without a ring gave an average number of hair follicles of 9.76 with a standard deviation of 4.53. The differences between both groups are statistically very significant with p-value of 0.002. Discussion: The results obtained prove that there is a direct influence of persistent, non-aggressive friction on the hair density of human skin on the finger. It was verified that there is a 28.3% decrease in the average values of the follicles, which can be considered to be an important effect. Conclusions: It can be concluded that the hypothesis initially proposed to explain the appearance of the vermillion border in Homo sapiens is plausible. Also that the friction between lips, caused by the spoken language, especially its bilabial syllables, can be the origin, as in the case of a ring rubbing against the skin of a finger over several years.
