Go­ing With the Grain

It took thou­sands of years, but Amer­ica’s found­ing farm­ers de­vel­oped the grain that would fuel civ­i­liza­tions—and still does

Smithsonian Magazine - - Prologue -

SOME­TIMES IT ’S THE LIT TLE things that count.

Movie ar­chae­ol­o­gists are of­ten pic­tured tri­umphantly ex­tract­ing pre­cious ob­jects from the earth, in­stantly solv­ing long-stand­ing mys­ter­ies. Think of In­di­ana Jones’ Cross of Coron­ado, Staff of Ra and Ark of the Covenant. Real ar­chae­ol­o­gists mostly find small, al­most val­ue­less ob­jects—and won’t know for years, or decades, what mys­tery they are re­solv­ing. Con­sider this an­cient ear of maize, which Wal­ter Hough pulled out of a New Mex­ico cave more than a cen­tury ago.

Hough worked at the Smithsonian Na­tional Mu­seum of Nat­u­ral His­tory (the repos­i­tory of this ar­ti­fact) from 1886 to 1935. A kindly man with a stat­ic­cling mem­ory who hunted ar­row­heads as a boy in West Vir­ginia, he spent most of his ca­reer on the un­sung but vi­tal task of cat­a­loging the mu­seum’s col­lec­tions. But he also took field trips into the South­west, and in Septem­ber 1905 he spent 12 days in what he called an “in­ter­est­ing cave.” It was in a bluff 150 feet above the Tu­larosa River, in New Mex­ico, about 30 miles east of the Ari­zona bor­der. Be­cause the cli­mate there is ex­tremely dry, vir­tu­ally noth­ing in the cave had de­cayed. For­merly used by early colonists as a don­key cor­ral, the cave was full of “rub­bish and the drop­pings of animals, to a depth of 8 feet,” Hough wrote. Just walk­ing around kicked up a chok­ing cloud of dust that forced re­searchers to wear gog­gles and cover their faces.

De­spite the ter­ri­ble con­di­tions, the re­searchers made an im­pres­sive haul: dried turkey ca­dav­ers, mam­mal bones, bro­ken crock­ery, a brush made from grass, in­cense pipes, stones for grind­ing, cig­a­rettes made from reeds, yucca-leaf san­dals—and about a dozen maize cobs, some with ker­nels in­tact. (Ar­chae­ol­o­gists typ­i­cally call the grain “maize,” rather than “corn,” be­cause mul­ti­col­ored in­dige­nous maize, usu­ally eaten af­ter dry­ing and grind­ing, is strik­ingly un­like the large, sweet yel­low-ker­nel cobs con­jured up by the word “corn.”) Hough was work­ing be­fore ar­chae­ol­o­gists had the tools to ac­cu­rately date ar­ti­facts, or even, pre-GPS, to note their ex­act lo­ca­tion. He sim­ply recorded the lo­cale of his finds and car­ried them back to Wash­ing­ton, D.C.

It would be four and a half decades be­fore Paul Sid­ney Martin, an ar­chae­ol­o­gist at Chicago’s Field Mu­seum, ex­am­ined Hough’s re­ports and fol­lowed in his foot­steps. Most ar­chae­ol­o­gists spe­cial­iz­ing in the South­west be­lieved that its ear­li­est in­hab­i­tants were the Anasazi (as the an­ces­tral Pue­blo were then known), who built cliff dwellings in Mesa Verde, 225 miles north of Tu­larosa Cave. But a few experts ar­gued that the Tu­larosa area had housed a dif­fer­ent cul­ture, called the Mo­gol­lon, af­ter a nearby moun­tain range. To re­solve what was be­com­ing a bit­ter con­tro­versy, Martin and his co-work­ers went to Tu­larosa Cave in June 1950—the first re­searchers there since Hough. In two sum­mers, they un­earthed tens of thou­sands of ar­ti­facts. And they made a con­vinc­ing case that the pot­tery they found—espe­cially starkly beau­ti­ful black-and-white rem­nants—looked noth­ing like Anasazi handi­work.

Among the Tu­larosa ob­jects were, as­ton­ish­ingly, 33,000 ears of an­cient maize. For­tu­itously, Martin had ac­cess to a brand-new tech­nol­ogy: ra­dio­car­bon dat­ing, just in­vented at the Uni­ver­sity of Chicago. It can de­ter­mine the age of plant re­mains and other or­ganic ma­te­ri­als. In­deed, the Tu­larosa cobs were among the first ar­chae­o­log­i­cal finds ever car­bon-dated. Martin

re­ported that some of the cobs were as old as 2,500 years. That sug­gested the cave had been in­hab­ited be­fore the Anasazi—key ev­i­dence, along with the un­usual cave ar­ti­facts, for a sep­a­rate Mo­gol­lon cul­ture.

From about A.D. 200 to the ar­rival of the Spa­niards, the Mo­gol­lon had oc­cu­pied most of what is now Sonora and Chi­huahua in Mex­ico as well as parts of south­ern Ari­zona and New Mex­ico. Their an­ces­tors be­gan as for­agers, then switched to agri­cul­ture, in­clud­ing the cul­ti­va­tion of maize, which helped fuel the flow­er­ing of Mo­gol­lon cul­ture. The Mo­gol­lon, in turn, played a large role in in­tro­duc­ing maize to so­ci­eties north of the Rio Grande, a piv­otal event as im­por­tant to North Amer­ica as the ar­rival of rice was to China or wheat to the Mid­dle East.

Hough and Martin didn’t have the sci­en­tific tools to an­a­lyze the ge­netic makeup of their maize spec­i­mens and trace pre­cise ori­gins or lin­eage. Per­haps hop­ing that fu­ture re­searchers would pore over his finds as he had pored over Hough’s, Martin and his co­work­ers sealed thou­sands of an­cient cobs in plas­tic bags that are stored to­day at the Field Mu­seum—the world’s great­est col­lec­tion of Mo­gol­lon ar­ti­facts and re­mains.

Lately re­searchers us­ing DNA probes and other tech­nolo­gies have been de­tail­ing the roughly 9,000-year process by which Na­tive Amer­i­cans trans­formed teosinte, the small­ish semitrop­i­cal grass with no ears or cobs, into maize, a pro­duc­tive, elab­o­rate plant that can thrive in a cool tem­per­ate cli­mate. In a 2003 anal­y­sis of cobs from Tu­larosa and lo­ca­tions in Mex­ico, re­searchers found that the ear­li­est sam­ples, some 6,300 years old, were ap­par­ently bred by peo­ple fo­cused on boost­ing the crop yield by in­creas­ing the size of cobs and ker­nels. Later, in Mo­gol­lon times, grow­ers were se­lect­ing for starch and grain qual­i­ties use­ful in mak­ing tor­tillas and tamales.

The transformation of a weedy grass into one of the world’s most im­por­tant food­stuffs—think of the enor­mous stalks of corn rip­pling across Mid­west­ern fields—is far more com­plex than any­thing we can do to­day in a lab, even with all our ge­netic prow­ess. How the con­ti­nent’s first farm­ers ac­com­plished that feat is a mys­tery. Drab de­bris found in a cave may hold the clues.

Car­bon-dat­ing tech­niques have now iden­ti­fiedthis an­cient maize cob at about 950 to 1,000 years old.

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