Page 1023 of Wine Grapes brought me to a shuddering halt. Not that I'd read the preceding 1022 pages, instead skimming through Jancis Robinson's preface, then diving straight in for the low-down on "syrah", also known as shiraz.
It seems Australia's national red hero isn't what we thought. Authors Jancis Robinson, Julia Harding and Jose Vouillamoz conclude, "Pinot is a very likely great-grandparent of syrah, which challenges the supposition that they have completely different origins."
DNA parentage analysis by French and American scientists in 1998 established shiraz as the love child of mondeuse blanche (the mother, from Savoie) and dureza (the father, from Ardeche).
This fortuitous and altogether spontaneous mating could have occurred only had the two shared the same viticultural bed. And in 2008, researchers Meredith and Boursiquot concluded the most likely place to find the two cultivated together would have been in the French Rhone-Alpes region, probably in the Isere.
But where and how does pinot noir come into the shiraz family tree? Something called probabilistic DNA analysis by Vouillamoz and Grando in 2006 established dureza, shiraz's father, as "a sibling of teroldego", a variety from Trentino in northern Italy. "This was the first evidence of a close genetic link between two varieties on different sides of the Alps," Robinson writes.
And it continues, ''Since syrah is a progeny of dureza, it is therefore a nephew/niece of teroldego. Vouillamoz and Grando have also detected a second-degree genetic relationship between pinot and both dureza and teroldego, which means that pinot could be their grandparent, grandchild, uncle/aunt, nephew/niece or half-sibling. Since pinot was already known in France and in the Tyrol in the 14th century, its cultivation pre-dates that of both dureza and teroldego and it is logical to consider pinot as their ancestor, either their grandparent or their uncle/aunt. Therefore, pinot is very likely great-grandparent of syrah."
The revelation of shiraz's lineage dragged me back to Robinson's preface, where she had warned of surprises ahead. I have on my bookshelf well-thumbed copies of her Vines, Grapes and Wines (1986) and the first and last of three editions of The Oxford Companion to Wine - the latter containing updates of her previous work on grape varieties.
But Robinson advises us to discard this previously authoritative work, "as this book is so much more up-to-date and comprehensive than either of my previous works on the subject".
The book's many revelations rely on DNA profiling, recently developed probabilistic analysis (capable of finding more distant relationships even in the absence of known parents) and cross-referencing with historical cultivation records.
Robinson says Australian scientists established the first grape DNA profile in 1993. Four years later, Californian scientists revealed Bordeaux's noble red variety, cabernet sauvignon, as a likely natural crossing of cabernet franc and the white variety sauvignon blanc. Knowledge has grown exponentially since then.
Robinson says her near-1300-page book "provides readers with virtually every DNA result published before August 31, 2011 as well as with dozens of unpublished results and 14 pedigree diagrams exclusive to us that reveal many new, sometimes unexpected, familial relationships".
Despite the depth of recent discoveries, many of the boxes in the pedigree diagrams contain question marks representing unknown family members. Perhaps these identities will be discovered in coming decades.
In the case of shiraz, for example, we know one of its great-grandparents (pinot) but not pinot's mate. Nor do we know shiraz's grandparents. Other diagrams in the syrah family tree offer several possible options for its genetic relationship with the white variety, viognier.
Robinson estimates the number of vine varieties in the world at 10,000, members of about six species (the book limits itself to 1368 of them). That seems an extraordinary number, despite the steadily growing range of varietal names appearing on bottles. But Robinson says they are all known to be producing commercial quantities of wine.
The book offers beautiful colour plates of many vine varieties, depicting leaf, stem and grape bunches.
For each variety, the authors detail berry colour, principal synonyms, varieties commonly mistaken for it, origins and parentage, viticultural characteristics, where it's grown and what it tastes like.
Under "syrah", for example, we learn France claims the No. 1 position, with 68,587 hectares in the ground in 2009. Australia claims second place, with 43,977 hectares in 2008.
The introduction covers a broad introduction to the grape vine, including varieties, a description of mutations and clones, the basics of vine breeding, rootstocks, grafting and DNA profiling. The book also lists varieties by country of origin.
Wine Grapes is a towering and original work, a reference book for the world's wine industry. And for wine drinkers it reveals much about the vines that give us such pleasure.
>>Wine Grapes: A complete guide to 1368 vine varieties, by Jancis Robinson, Julia Harding and Jose Vouillamoz (Allen Lane, an imprint of Penguin, October 2012, $199).