Probing ancient shipwrecks with DNA
Jan 04,2008 00:00 by Bend_Weekly_News_Sources

Stud­y­ing an an­cient Greek ship­wreck, sci­en­tists say, they’ve found they can de­code an­cient DNA to learn about the orig­i­nal con­tents of jars sunk­en for over 2,000 years.

It’s a feat “no one thought was even pos­si­ble,” wrote Ma­ria Hans­son of Lund Uni­vers­ity in Swe­den, one of the re­search­ers, in an e­mail. The disco­very “o­pens up a whole new field of mo­lec­u­lar ar­chae­o­lo­gy,” she added, as sci­en­tists could use the tech­nique to gain in­sights in­to an­cient ag­ri­cul­ture and trad­ing net­works.

An­cient am­pho­rae, or stor­age jars, at the Chi­os ship­wreck site. (Cour­te­sy Chi­os 2005 Ship­wreck Sur­vey - WHOI, Hel­len­ic Min­is­try of Cul­ture: Eph­or­ate of Un­der­wa­ter An­tiq­ui­ties, Hel­len­ic Cen­ter for Ma­rine Re­search)

Mod­el of a 4th-century B.C. Greek mer­chant ship based on the Ky­re­nia, a wreck sal­vaged in 1967.

An­cient Med­i­ter­ra­nean civ­il­iz­a­tions, some of the world’s ear­li­est, of­ten used ce­ram­ic jars called am­pho­rae as ship­ping con­tain­ers. In­vented by the Ca­naan­ites of the Near East in the 16th cen­tu­ry B.C., am­pho­rae took on var­ied styles in dif­fer­ent re­gions and time pe­ri­ods, wrote Hans­son and a col­league in a pa­per re­port­ing their work.

Piles of am­pho­rae of­ten re­main as lone, mute wit­nesses to an­cient ship­wrecks where the boats them­selves have been long since eat­en away. 

But re­search­ers try­ing to learn the jars’ orig­i­nal con­tents usu­ally come up dry, ac­cord­ing to Hans­son and col­league Bren­dan Fo­ley of the Woods Hole Oce­a­no­gra­phic In­sti­tu­tion in Mas­sa­chu­setts. That’s be­cause the am­pho­rae only in­fre­quent­ly con­tain vis­i­ble clues, such as ol­ive pits.

An­cient DNA molecules, though de­grad­ed with time, could supply some of the needed ev­i­dence, wrote the pair, whose find­ings ap­pear in the ad­vance on­line edi­tion of The Jour­nal of Ar­chae­o­log­i­cal Sci­ence.

The re­search­ers scraped ce­ram­ic from in­side two am­pho­rae from a 4th-cen­tu­ry B.C. ship­wreck found near the Greek is­land of Chi­os in 2004. The wreck, about 60 me­ters (200 feet) un­der­wa­ter, has drawn head­lines be­fore be­cause—being to deep to ex­plore by con­ven­tion­al diving—in­vest­i­ga­t­ors have mapped it using robotic de­vices.

Adding an­oth­er new tech­nol­o­gy to the proj­ect, Hans­son and Fo­ley an­a­lyzed small DNA frag­ments found trapped in the pot­tery. 

They de­ter­mined that one ves­sel probably con­tained ol­ive oil fla­vored with oreg­a­no, a sur­prise be­cause his­to­ri­ans have be­lieved that am­pho­rae of that style from Chi­os usu­ally car­ried wine, they wrote. Chi­os was known for “fine and dis­tinc­tive vin­tages,” they not­ed, but the find sug­gests Chi­an ag­ri­cul­tur­al ex­ports might have been more di­verse than gen­er­ally as­sumed.

The oth­er jar, they wrote, con­tained DNA of mas­tic—a shrub cul­ti­vat­ed on Chi­os—or of pis­ta­chio, a re­lat­ed plant. Schol­ars have hy­poth­e­sized that an­cient Chi­ans used mas­tic res­in as a wine pre­serv­a­tive and fla­vor­ing, Hans­son and Fo­ley wrote. 

Some an­cient foods, they added, are more likely than oth­ers to leave ge­net­ic call­ing cards be­hind. For in­stance, be­cause the sec­ond jar was thought to have likely con­tained wine, they checked for grape DNA, but found none. It may have washed away be­cause wine dis­solves in wa­ter bet­ter than oil or res­in, Hans­son and Fo­ley ob­served. But overall, they wrote, the find­ings “con­tribute de­fi­nite ev­i­dence for Clas­si­cal Greek com­mod­ity ex­change and open new vis­tas for mo­lec­u­lar archeolog­i­cal anal­y­ses.”

Courtesy of World-Science