DNA from a 2,500-year-old battlefield in Sicily reveals that mercenary soldiers were common, if not the Homeric ideal.

A mᴀss grave of troops from the second Battle of Himera in Sicily in 409 B.C. One-fourth of the combatants are thought to have been mercenaries, compared to two-thirds in the first Battle of Himera seven decades earlier.Credit…Stefano Vᴀssallo

Wherever there is an out-of-the-way war, there will be mercenaries — hired fighters whose only common bond may be a hunger for adventure. Some join foreign armies or rebel forces because they believe in the cause; others sign on because the price is right.

“Being a wage earner had some negative connotations — avarice, corruption, shifting allegiance, the downfall of civilized society,” said Laurie Reitsema, an anthropologist at the University of Georgia. “In this light, it is unsurprising if ancient authors would choose to embellish the Greeks for Greeks aspect of the battles, rather than admitting they had to pay for it.”

But research published on Monday in the Proceedings of the National Academy of Sciences suggests that the ancestry of the troops defending Himera was not as strictly Greek as historical accounts of the time would have it.

The victory was widely seen as a defining event for Greek idenтιтy. But the new study, an analysis of degraded DNA from 54 corpses found in Himera’s recently unearthed west necropolis, found that the communal graves were largely occupied by professional soldiers from places as far-flung as those known today as Ukraine, Latvia and Bulgaria.

The finding ʙuттresses research published last year in which Katherine Reinberger, a bioarchaeologist at the University of Georgia, and her colleagues performed a chemical analysis of the tooth enamel of 62 fallen fighters buried near Himera’s ancient battlefield, where two major clashes played out: one in 480 B.C., when Himeran forces defeated the Carthaginian general Hamilcar Mago, and a second battle seven decades later, when Hamilcar’s grandson returned for revenge and Himera was destroyed. Dr. Reinberger’s team concluded that about one-third of those who fought in the first conflict were locals, compared with three-fourths in the later battle. Dr. Reitsema is a principal author on both studies.

The ruins of the Temple of Victory, built after the first Battle of Himera in 480 B.C. and razed after the city’s capture in 409 B.C.Credit…Alamy

David Reich, a geneticist at Harvard whose lab generated the data, noted that their paper “suggests that Greeks minimized a role for mercenaries, potentially because they wanted to project an image of their homelands being defended by heroic Greek armies of citizens and the armored spearmen known as hoplites.” Presumably, armies staffed with commandos-for-hire would undermine this picture.

The tyrants who ruled Greek Sicilian cities in the Hellenic Age recruited soldiers of fortune for territorial expansion, and in some cases because those rulers were wildly unpopular with their citizenry and required bodyguards. “The recruitment of mercenaries even spurred the use of coinage in Sicily to pay them,” Dr. Reitsema said.

The Sicily of antiquity, rich in resources and strategically located, was home to both Greek and Carthaginian colonies, which for a long time coexisted amicably. But when Terillus, tyrant of Himera, was ousted by his own people in 483 B.C., he called on his Carthaginian allies to help him retake the city.

Three years later, the Carthaginian general Hamilcar Mago sailed from North Africa to Himera with an expeditionary force estimated by Herodotus at more than 300,000 strong. (Modern historians put the figure closer to 20,000.) But cavalry and foot soldiers from two neighboring Greek Sicilian city-states, Syracuse and Agrigento, came to Himera’s aid, and Hamilcar’s troops were routed and his ships set ablaze. When all seemed lost, the general is said to have killed himself by leaping into a pyre.

Determining which bones were Himeran and which were Carthaginian was a matter of location. Alissa Mittnik, a Harvard geneticist responsible for the genomic analysis, said the deliberate burial of the fallen within the necropolis denoted that they were part of the Himeran army rather than the enemy.

“While we know nothing of the manner in which members of the Carthaginian army were buried,” she said, “it was typical in Greek warfare for the victor to allow the enemy access to the battlefield to remove its ᴅᴇᴀᴅ.”

Chemical isotopes in the mercenaries’ bones indicated that the soldiers were born far away and that their parents and grandparents were not immigrants. And the ancient genomes were sequenced and compared to all published genomes, Dr. Reich said: “The ones those new genomes are closest to are those from Ukraine and Latvia.”