Scientists claim in a new study that the Habsburg lower lip, also known as the Habsburg jaw, was formed due to 200 years of intermarriage. So it has a distinctive facial shape, which is a typical feature of the royal family of the same name. Geneticists and surgeons analyzed the deformities in various portraits of the royal dynasty and compared them to the extent of inbreeding in their family tree. However, until now it was not clear whether the characteristic line of jaws in the family is the result of intermarriage or not.
Habsburg lower lip under the magnifying glass
So this is the first study to suggest a direct relationship between intermarriage and facial morphology. The so-called “Habsburg jaw,” typical of the dynasty of Spanish and Austrian kings and their wives, is attributed to incest, according to new results published in the “Annals of Human Biology.” The new research combined diagnosis of facial deformity using historical portraits with genetic analysis of the degree of relatedness. In this way, the family tree researchers wanted to determine whether there was a direct connection. For this reason, they also examined the genetic basis of the relationship.
Generations of intermarriage ensured the family's influence over a European empire including Spain and Austria for more than 200 years, but led to its downfall when the last Habsburg monarch failed to produce an heir. However, no studies have yet confirmed whether the pronounced chin known as the “Habsburg jaw” was a result of incest.
Researchers recruited 10 oral surgeons to diagnose facial deformity in 66 portraits of 15 members of the Habsburg dynasty. Despite different artistic styles, the portraits are characterized by a realistic approach to the human face. The surgeons were asked to diagnose 11 features of mandibular prognathism, also known as “Habsburg jaw,” as well as seven features of maxillary deficiency. The most famous of these are a protruding Habsburg lower lip and an overhanging tip of the nose.
Mary of Burgundy, who entered the family in 1477, had the lowest degree of both characteristics. From 1621 to 1640, mandibular prognathism was most pronounced in Philip IV, King of Spain and Portugal. The researchers most often diagnosed the upper jaw deficiency in five family members: Maximilian I (regent from 1493), his daughter Margaret of Austria, his nephew Charles I of Spain, Charles' great-grandson Philip IV and the last in the Habsburg line, Charles II
Clear results
The study authors found a correlation between the two conditions. This suggests that the Habsburg lower lip is actually characterized by the two and that they share a common genetic basis. They calculated the extent of the incest using an extensive family tree analysis that included more than 6,000 individuals from more than 20 generations. The researchers analyzed whether this was related to the degree of facial deformation. The team found a strong link between the level of intermarriage and that of prognathism in mandibles. The relationship with maxillary deficiency was also positive, but only statistically significant for two of the seven diagnosed features.
The causes of the connection between mixed marriages andsuch facial shapesare therefore still unclear. However, the authors suggest that the main effect of mating between relatives is to increase the likelihood that offspring will inherit identical forms of a gene from both parents, called genetic homozygosity. This reduces people's genetic fitness, so "Habsburg jaw" should be considered a recessive condition.
However, the authors noted that the study involved only a small number of people. It is possible that the prevalence of the Habsburg lower lip is due to the random appearance of traits or genetic variations. They consider this scenario unlikely, but cannot rule it out.
“Although our study is based on historical figures, incest is still common in some regions and among some religious and ethnic groups. “It is therefore important today to study the effects,” says Vilas. “The Habsburg dynasty serves as a kind of human laboratory for researchers because the spectrum of incest is so wide.”
Read more about ithere.
