Jaw-drop­ping se­cret of the Hab­s­burg jaw

Re­gal fea­ture seen as sign of blue blood ‘WAS spread by in­breed­ing’

Scottish Daily Mail - - Life - By Colin Fer­nan­dez Sci­ence Correspond­ent

THE jut­ting Hab­s­burg jaw seen in some of Europe’s most prom­i­nent royal fam­i­lies has long been sus­pected to be the re­sult of in­breed­ing.

Now sci­en­tists have shown a di­rect con­nec­tion be­tween mar­riages of peo­ple who are too closely re­lated and the ge­netic con­di­tion.

The de­for­mity was a dis­tinc­tive fea­ture of mem­bers of the Hab­s­burg – or Haps­burg – dy­nasty of Span­ish and Aus­trian kings and their wives for more than 200 years.

Re­search in the An­nals of Hu­man Bi­ol­ogy com­bined di­ag­no­sis of fa­cial de­for­mi­ties us­ing his­tor­i­cal por­traits with ge­netic anal­y­sis of the de­gree of re­lat­ed­ness.

Lead re­searcher Pro­fes­sor Ro­man Vi­las, of the Univer­sity of San­ti­ago de Com­postela in Spain, said: ‘The Hab­s­burg dy­nasty was one of the most in­flu­en­tial in Europe, but be­came renowned for in­breed­ing, which was its even­tual down­fall.

‘We show for the first time that there is a clear pos­i­tive re­la­tion­ship be­tween in­breed­ing and ap­pear­ance of the Hab­s­burg jaw.’

Ten sur­geons who spe­cialise in the face and the jaw were asked to score the de­gree of sever­ity of fa­cial de­for­mity in 66 por­traits of 15 mem­bers of the Hab­s­burgs.

They looked for 11 fea­tures of mandibu­lar prog­nathism, or Hab­s­burg jaw, as well as seven fea­tures of max­il­lary de­fi­ciency – the most recog­nis­able of which are a prom­i­nent lower lip and an over­hang­ing nasal tip.

They found the most pro­nounced ef­fect of the first con­di­tion was in Philip IV, king of Spain from 1621 to 1665. And those most strongly af­fected by max­il­lary de­fi­ciency in­cluded Max­i­m­il­ian I (ruler of the Holy Ro­man Em­pire from 1493), his daugh­ter Mar­garet of Aus­tria and the last in the Hab­s­burg line: Charles II, Philip IV’s son.

The sci­en­tists de­tected a strong re­la­tion­ship be­tween the de­grees of in­breed­ing and mandibu­lar prog­nathism – as well as a less pro­nounced link be­tween in­breed­ing and max­il­lary de­fi­ciency.

The study also found a link be­tween the two con­di­tions, sug­gest­ing Hab­s­burg jaw is in fact char­ac­terised by them both and they share a ge­netic ba­sis. The ex­tent of in­breed­ing was cal­cu­lated from a fam­ily tree in­clud­ing more than 6,000 in­di­vid­u­als from more than 20 gen­er­a­tions.

The au­thors say their find­ings are ‘the first ev­i­dence of in­breed­ing de­pres­sion on the hu­man face’.

Why in­breed­ing leads to the fa­cial de­for­mity is un­clear. How­ever, the ex­perts sug­gest it is be­cause mat­ing with rel­a­tives in­creases chances of off­spring in­her­it­ing iden­ti­cal forms of a gene from both par­ents.

Runs in the fam­ily: Charles II and Philip IV of Spain

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