"Long before it's in the papers"
July 25, 2012

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Physics hints at historical truths in epics of old

July 25, 2012
Courtesy of the Institute of Physics
and World Science staff

Us­ing tech­niques bor­rowed from phys­ics, sci­en­tists have found that some of the most fa­mous his­tor­i­cal myths—in­clud­ing Home­r’s the Il­i­ad—ex­hibit mea­sur­ably real­is­tic qual­i­ties.

The results suggest some as­pects of these ta­les may be true, though they clearly con­tain lots of fan­ta­sy, said the re­search­ers, who an­a­lyzed the char­ac­ters’ in­ter­rela­t­ion­ships and com­pared them to real-life so­cial net­works.

“We’re not say­ing that this or that ac­tu­ally hap­pened, or even that the in­di­vid­ual peo­ple por­trayed in the sto­ries are real; we are say­ing that the over­all so­ci­e­ty and in­ter­ac­tions be­tween char­ac­ters seem real­is­tic,” said Pádraig Mac Car­ron of Cov­en­try Uni­vers­ity in the U.K., one of the in­ves­ti­ga­tors.

Ar­chae­o­log­i­cal ev­i­dence has al­so been in­ter­preted as in­di­cat­ing that some el­e­ments of the myths, such as spe­cif­ic loca­t­ions, land­marks and char­ac­ters, are likely to have ex­isted.

In the stu­dy, pub­lished on­line July 25 in the jour­nal Euro Phys­ics Let­ters, Ma­c Car­ron and Ralph Kenna of the uni­vers­ity per­formed de­tailed text anal­y­ses of the Il­i­ad, the Eng­lish po­em, Be­o­wulf, and the Irish ep­ic, the Táin Bó Cuail­nge.

They found that the in­ter­ac­tions be­tween the char­ac­ters in all three myths were con­sist­ent with those seen in real so­cial net­works. The re­search­ers al­so com­pared the myths to four known works of fic­tion—Les Mis­érables, Rich­ard III, Fel­low­ship of the Ring, and Har­ry Pot­ter —and no­ticed clear dif­fer­ences.

The re­search­ers cre­at­ed a database for each of the three sto­ries and mapped out the char­ac­ters’ in­ter­ac­tions. There were 74 char­ac­ters iden­ti­fied in Be­o­wulf, 404 in the Táin and 716 in the Il­i­ad. Each char­ac­ter was as­signed a num­ber, or de­gree, based on how pop­u­lar they were, or how many links they had to oth­er char­ac­ters. The re­search­ers then meas­ured how these de­grees were dis­trib­ut­ed through­out the whole net­work.

The types of rela­t­ion­ships that ex­isted be­tween the char­ac­ters were al­so an­a­lyzed us­ing two spe­cif­ic cri­te­ria: friend­li­ness and hos­til­ity. “Friendly” links were made if char­ac­ters were re­lat­ed, spoke to each oth­er, spoke about one anoth­er or it is oth­erwise clear that they know each oth­er am­i­ca­bly. “Hos­tile” links were made if two char­ac­ters met in a con­flict, or when a char­ac­ter clearly dis­played an­i­mos­ity against some­body they know.

The three myths were found to be si­m­i­lar to real-life net­works in three ways: they had si­m­i­lar “de­gree dis­tri­bu­tions,” were “as­sor­ta­tive” and vul­ner­a­ble to tar­geted at­tack. As­sor­ta­ti­vity is the ten­den­cy of a char­ac­ter of a cer­tain de­gree to in­ter­act with a char­ac­ter of si­m­i­lar pop­u­lar­ity. Be­ing vul­ner­a­ble to tar­geted at­tack means that if you re­move one of the most pop­u­lar char­ac­ters, it leads to a break­down of the whole net­work – nei­ther of which ap­pears to hap­pen in fic­tion, the re­search­ers said.

Of the three myths, the Táin is the least be­lieved. But Mac Car­ron and Kenna found that its ap­par­ent ar­ti­fi­cial­ity can be traced to only 6 of the 404 char­ac­ters.

“In terms of de­gree dis­tri­bu­tions, all three myths were like real so­cial net­works; this was­n’t the case for the fic­tional net­works. Re­mov­ing the ep­on­y­mous pro­tag­o­nist from Be­o­wulf al­so made that net­work as­sort­a­tive, like real net­works,” Mac Car­ron said. “For the Táin we re­moved the ‘weak links’ as­so­ci­at­ed with the top six most con­nect­ed char­ac­ters which had pre­vi­ously off­set the de­gree dis­tri­bu­tion; this ad­just­ment made the net­work as­sort­a­tive.”

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Using techniques borrowed from physics, scientists have found that some of the most famous historical myths—including Homer’s the Iliad—exhibit surprisingly realistic qualities. The findings hint that some aspects of these tales may be true, though they clearly contain lots of fantasy, said the researchers, who analyzed the characters’ interrelationships and compared them to real-life social networks. “We’re not saying that this or that actually happened, or even that the individual people portrayed in the stories are real; we are saying that the overall society and interactions between characters seem realistic,” said Pádraig Mac Carron of Coventry University in the U.K., one of the investigators. Archaeological evidence has also been interpreted as indicating that some elements of the myths, such as specific locations, landmarks and characters, are likely to have existed. In the study, published online July 25 in the journal Europhysics Letters, Mac Carron and Ralph Kenna of the university performed detailed text analyses of the Iliad, the English poem, Beowulf, and the Irish epic, the Táin Bó Cuailnge. They found that the interactions between the characters in all three myths were consistent with those seen in real social networks. The researchers also compared the myths to four known works of fiction—Les Misérables, Richard III, Fellowship of the Ring, and Harry Potter —and noticed clear differences. The researchers created a database for each of the three stories and mapped out the characters’ interactions. There were 74 characters identified in Beowulf, 404 in the Táin and 716 in the Iliad. Each character was assigned a number, or degree, based on how popular they were, or how many links they had to other characters. The researchers then measured how these degrees were distributed throughout the whole network. The types of relationships that existed between the characters were also analysed using two specific criteria: friendliness and hostility. Friendly links were made if characters were related, spoke to each other, spoke about one another or it is otherwise clear that they know each other amicably. Hostile links were made if two characters met in a conflict, or when a character clearly displayed animosity against somebody they know. The three myths were found to be similar to real-life networks in that they had similar “degree distributions,” were “assortative” and vulnerable to targeted attack. Assortativity is the tendency of a character of a certain degree to interact with a character of similar popularity. Being vulnerable to targeted attack means that if you remove one of the most popular characters, it leads to a breakdown of the whole network – neither of which appears to happen in fiction. Of the three myths, the Táin is the least believed. But Mac Carron and Kenna found that its apparent artificiality can be traced to only 6 of the 404 characters. “In terms of degree distributions, all three myths were like real social networks; this wasn’t the case for the fictional networks. Removing the eponymous protagonist from Beowulf also made that network assortative, like real networks,” Mac Carron said. “For the Táin we removed the ‘weak links’ associated with the top six most connected characters which had previously offset the degree distribution, this adjustment made the network assortative.”