An investigation worthy of CSI revealed a genetic match, a missing triplet, and an unexpected birthplace

For generations, hard-working contadini in Puglia quenched their thirst with Primitivo. Fruity, alcoholic, and drinkable when young, this was sturdy peasant stuff, a supper staple in a sun-drenched land.

Thousands of miles away, Gold Rush pioneers enjoyed a similar wine, Zinfandel—and for the same reasons: It flourished in California’s hot, dry climate, it produced abundant sweet fruit, and it didn’t require aging.

Modern science has established that Primitivo and Zinfandel are genetic twins, separated at birth some two centuries ago. But it took 35 years to trace the family tree and find its roots. That investigation was worthy of CSI, entailing DNA fingerprinting, isozyme match-ups, and palate-based intuition. It’s unquestionably one of wine’s great detective stories.

For much of the 20th century, Zinfandel was assumed to be an American grape, our only indigenous vitus vinifera. But some suspected it had been brought from Italy, owing to surnames like Sebastiani, Simi, Seghesio, and Foppiano that dominated the early history of California wine.

In reality, Zinfandel first landed on Eastern shores. It was imported in the 1820s by a Long Island horticulturalist named George Gibbs, who obtained it from the Austrian Imperial Nursery in Vienna, then sold it to nurseries in Boston. Soon “Zinfandal” was all the rage among Northeastern bluebloods—but not as a wine grape. Rather, it was cultivated in hothouses as a table grape.

By the 1850s, that fad had subsided as Concord proved it could endure New England’s bitter winters. Zinfandel moved west, traveling with the enterprising nurserymen who followed the Gold Rush migration. In 1857, the first Zinfandel wine appeared in Napa; by 1900, it was the most widespread grape in California.

The next century, Zinfandel’s fortunes ebbed with Prohibition, then flowed like a tsunami with the white Zinfandel boom. Around the time Zin was beginning its transition from undistinguished jug wine to crafted premium wine, a UC-Davis researcher took a fateful trip to Puglia. Drinking the local wine, Austin Goheen thought it tasted like Zinfandel. Once he saw the Primitivo vines, his conjecture turned serious. In 1968, UC-Davis ampelographers declared Goheen’s vine cuttings identical to Zinfandel based on external appearances. By 1975, PhD candidate Wade Wolfe could support that claim using isozyme fingerprinting. But the ultimate test—DNA—had to wait two more decades to make its way onto the viticultural stage.

Primitivo’s origins were equally vague. The assumption was that it had been in southern Italy since pre-Grecian times, but no documents supported this. Primitivo first showed up in government records in the 1870s, which gave rise to the theory that it was actually brought to Italy from America. However, church records revealed that Primitivo was identified in the late 1700s by Don Francesco Filippo Indellicati, a priest from Gioia del Colle near Bari. He spotted a type of grape that ripened early (primo). Don Francesco isolated it, dubbed it Primitivo, and began cultivating it in Gioia. Contemporaries suggested it might be a selection of Zagarese—that is, a grape from Zagreb, Croatia.

From central Puglia, it spread south to Manduria (today the most esteemed of Primitivo DOCs) and down the heel of the boot. Primitivo is now among Italy’s 10 most widely planted reds. Like Zinfandel, it had a long history as a bulk wine, and its high alcohol and plush fruit made it attractive to wine merchants in Tuscany and Piedmont, who used it to beef up their thinner northerly wines.

In 1996, UC-Davis geneticist Carole Meredith cracked the DNA code for Cabernet Sauvignon. That set Mike Grgich into action. This Croatian-born owner of Napa’s Grgich Hills Estate was convinced that Zinfandel was related to the Croatian grape Plavac Mali (plah-vahtz mahlee). He relentlessly lobbied Meredith to go to Croatia. Working with the University of Zagreb, the geneticist collected 150 samples of Plavac Mali from the Dalmatian Coast. (The existence of so many cultivars was a clue to its ancient roots there; more time in a region allows for more mutations to occur in the field.)

By 2001, the family tree was in place: Zinfandel and Primitivo were genetic twins. But Plavac Mali turned out to be their offspring; its other parent was Dobričić, from an island off the Dalmatian Coast. Further sleuthing in Dalmatia uncovered a triplet: Crljenak Kasteljanski (kerl-yen-ick kas-tel-yan-ski). Nine lonely vines had survived.

With that discovery, the history fell in place: Croatia was the ancestral home of Crljenak/Primitivo/Zinfandel, at least since ancient times. (Beginning in the 4th C. b.c., the Dalmatian Coast was an important Grecian throughway, so it’s possible the grape originally came from Greece or Asia Minor.) Crljenak began its worldwide journey in the late 1700s, skipping across the Adriatic to Puglia (hence the historic reference to Zagarese grapes). Since Croatia was part of the Austrian Empire, Crljenak vine cuttings entered the Imperial Nursery in Vienna and from there traveled to Long Island.

It’s not yet possible to taste the triplets side by side. Crljenak is still rare, though there are now 2,000 vines. Grgich cultivates 17 of them, alongside Plavac Mali at his new Croatian winery, Grgic Vina. That’s enough for one barrel.

But it’s easy to get well acquainted with the twins. It’s not so easy, however, to pin down their character, due to peculiarities of the grape. The skin is thin, so it raisins easily. More importantly, the cluster ripens unevenly, so a single bunch can contain green berries, ripe red grapes, and raisins. That’s the wild card, the place where wineries define their style. Vinify the whole motley bunch, and you’ve got a decent, cheap pizza wine. Go to the trouble to manage leaf canopy, trim unwanted grapes, and do multiple passes at harvest, and you’ve got a distinctive, handcrafted wine—at a much higher price.

Another stylistic decision is when to harvest. This affects both the alcohol level and the fruit character of the wine. Pick at lower sugar levels (23º Brix) and strawberry comes through. Let the grapes hang longer and cherry appears at 24ºBx. Wait until 25ºBx and you get blackberry flavors.

To examine the twins, I organized a tasting for my wine club. The first flight was a get-acquainted three-way pour. (We included a Plavac Mali for curiosity’s sake.) The next three flights were blind comparisons. Here’s the line-up:

Primitivo di Manduria, Koiné, $11
Ancient Vines Zinfandel, Cline, $18
Plavac Mali, Dingac Vinarija, $17
•
Piluna Primitivo Salento, Castello Monaci, $16
Sonoma Zinfandel, Seghesio, $27
•
Primitivo di Manduria, Ognissole, $18
Dry Creek Zinfandel, Quivira,  $20
•
Tradizione del Nonno Primitivo di Manduria, Pichierri $37
Geyserville Zinfandel, Ridge, $42

Unexpectedly, my club went wild for the Plavac Mali. Though lighter-bodied and astringent, it had an intriguing layer of spice. This tied in popularity with the behemoth Pichierri Primitivo—interestingly, the most traditional contestant, as its name implies (“tradition of the grandfather”). Pichierri lets the grapes slightly over-mature on the vine, which gives the black fruit a rich, raisiny undertone with chocolate-coffee notes. (Amarone lovers, make note.) Interestingly, the dried or stewed fruit character one sometimes finds in Primitivo is a trait American winemakers seem to abhor in their Zinfandel, yet it strongly appealed to this group. I also liked the unabashedly modernist Primitivo from Ognissole, a Puglian estate owned by the Feudo di San Gregorio winery in Campania. This was a delicious bonbon: bright cherry wrapped in chocolate and clove, with a mouthwatering streak of acidity. 

Often the group was stumped in the blind comparisons. (That’s part of the fun.) But all agreed on the delectability of each wine and the diversity of the grape. Zin/Primitivo and its offspring found some converts that evening. Gather some friends and try it yourself. Cheers, salute, and zivjeli!

Published in the February 2010 issue of Tastes of Italia magazine.