The study also reported that no children born with light hair had the mark, meanwhile 47% of the children with dark hair having it.Since the last century, extensive research has been made regarding the prevalence of said spot in populations of mixed European-Amerindian ancestry. A publication from 1905, citing field research made by the anthropologist Frederick Starr, states that the spot is not present in Mestizo populations, however, if Starrs actual research is consulted it is observed the he declares that "seven Mayan children presented the spot, three mixed children didnt have it...", Starr therefore does not make an absolute judgement, as he does not say how many mixed children were analyzed in total. Nowadays it is completely accepted that the big majority of Mexicos and Latin Americas mixed-race populations have the Mongolian spot and that its presence works as an indicator of the actual degree of mestizaje present in a given population, having its lower frequency in Uruguay with 36%, followed by Argentina with an incidence 44%, Mexico with 50%-52%, 68% in Hispanic-Americans and 88% in highland Peruvians.A study performed in hospitals of Mexico City reported that, on average, 51.8% of Mexican newborns presented slate grey nevus, while it was absent on 48.2% of the analyzed babies.
According to the Mexican Social Security Institute nationwide, around half of Mexican babies have the slate grey nevus.Central American indigenous children were subjected to racism due to their slate grey nevus but progressive circles began to make having the slate grey nevus popular after the late 1960s.Highland Peruvians have the slate grey nevus. Treatment
As a congenital benign nevus, Mongolian spots do not require treatment and in most cases disappear before adolescence. No cases of malignant degeneration have been reported. Cultural terminology
The slate grey nevus is referred to in the Japanese idiom shiri ga aoi (尻が青い), meaning "to have a blue butt", which is a reference to immaturity or inexperience. In Mongolian language, it is known as "Хөх толбо". Korean mythology explains the nevus as a bruise formed when Samshin halmi or Samsin Halmoni (Korean: 삼신할머니), a shaman spirit to whom people pray around childbirth, slapped the babys behind to hasten the baby to quickly get out from the mothers womb. "Mongolian Mark", the middle third of the 2004–5 novel The Vegetarian, is named after the title characters nevus, which obsesses her brother-in-law. In Chinese, it is referred to as "青痕" (Pinyin: Qīng Hén; literally: blue mark). Among common folk it is said to be caused by the Buddhist goddess of childbirth Songzi Guanyin (Simplified Chinese: 送子观音; Pinyin: Sòng Zǐ Guān Yīn; literally: the goddess of baby sending) when she is slapping the babys backside, telling it to be born.