Wednesday, September 26, 2012

The Essential Iceland

“You cannot take the tunnel today,” proclaimed my friend Þórður.

It was too sunny. A brilliant sunny day in September of last year, and I was off on a roadtrip from Reykjavik to Reykholt, home of the greatest writer of the Middle Ages, the Icelandic chieftain Snorri Sturluson.

The fall colors were bright—as bright in Iceland as they are now, here in Vermont, something that surprised me.

So instead of taking the coast road north (and the time-saving tunnel under Hvalfjordur), I took Þórður's advice and drove inland from Iceland’s capital city to Thingvellir, where the ancient open-air parliament or Althing was held, and followed an old road north from there.

I was in the middle of writing Song of the Vikings, my biography of Snorri Sturluson, and I wanted to see the Iceland he saw. How better than in a jeep, driving the old road north from the Assembly Plains.

Snorri went this way on horseback. He was probably more comfortable on his smooth-gaited Icelandic horse than I was in my rented jeep. The road is washboarded—torturousmore than you can ask a set of shock-absorbers to handle.

The vast brown plain looks smooth from a distance, but it is full of broken ground, boulders, hidden streams, and crevices.

It’s desolate. One bus passed in two hours—a group of medieval studies students from the University of Iceland also taking advantage of this sunny day to tour from Thingvellir to Reykholt.

I pulled over to pee, and, of course, a second car came by, a regular car (not a jeep), and going rather fast, I thought, kicking up dust driving right into the sun. The old woman in the passenger’s seat looked horrified. She had a long, bumpy road to go.

A bit of silvery glacier, like an inverted smile. A raven kronking. A flock of little brown birds with wings of white. Patches of dirty old snow, of lichen burned a brilliant red. Long stretches of nothing but gold-brown rocks.

After three hours of slow driving and many stops for photos, I was very tired (too much of a good thing) and happy to come down into the valley and drive a paved road. There was grass beside the Geita, golden yellow with heavy seedheads, and red-leaved brush on the hillsides.

Along Hvitarsida, the White River snaked through golden birches tall as hedges. I came back a day or two later to picnic and watch the light play over the woodlands.

After a sprinkle of rain, Iceland’s autumn colors can be almost gaudy. As brilliant as the fall foliage in Vermont—though Iceland’s trees are too short to form that golden leafy canopy Vermont provides.

No waterfalls like this one in Vermont, though, with jets bursting out through the porous lava rock.

A rainbow welcomed me home to Reykholt, home of the 13th-century chieftain and writer, Snorri Sturluson. Song of the Vikings: Snorri and the Making of Norse Myths will be published October 30 by Palgrave Macmillan.

Join me again next Wednesday at for another writing adventure in Iceland or the medieval world.

Wednesday, September 19, 2012

The Flat Earth Error

How many times have you heard it said that people in the Middle Ages thought the world was flat?

When I was working on The Abacus and the Cross, my biography of the Scientist Pope, I was thrilled to find a map of the world drawn shortly before the year 1000. This map appears in a standard medieval geometry textbook. It is drawn as a circle, and a caption at the top explains that the circle depicts one hemisphere of the globe. Around the edge of the circle, another caption refers to the method devised by Eratosthenes in 240 B.C. for calculating the circumference of the earth. That method was well-known to medieval scholars, who routinely referred to the earth as “round as an apple” or an egg.

This map of the spherical world from before the year 1000 is in the Staatsbibliothek Berlin (Preussicher Kulturbesitz, Phill. 1833 (Rose 138), fol. 39v). It was published in 1996 in Autour de Gerbert d’Aurillac, le Pape de l’an Mil, edited by O. Guyotjeannin and E. Poulle.

Yet in the late 1980s, historian of science Jeffrey Burton Russell, author of Inventing the Flat Earth, found the “fact” that medieval people thought the earth was flat in a 1983 textbook for fifth-graders, a 1982 text for eighth-graders, and in the 1960, 1971, and 1976 editions of the college textbook, A History of Civilization. He even found it in the bestselling 1983 book, The Discoverers, by the former Librarian of Congress, Daniel Boorstin.

Two writers share most of the blame for this: Petrarch and Washington Irving.

The Italian writer Petrarch (1304-1374) is known for two things: developing the sonnet, and coining the term “the Dark Ages.” Sometimes called the first humanist, Petrarch divided history into Ancient (before Rome became Christian in the fourth century) and Modern (his own time). Everything in between was dark. Writes Russell, “The Humanists perceived themselves as restoring ancient letters, arts, and philosophy. The more they presented themselves as heroic restorers of a glorious past, the more they had to argue that what had preceded them was a time of darkness.” (Stephen Greenblatt, in his popular book, The Swerve, is still making this argument; I’ll discuss that in a future blog post.)

The humanists also had a political motive. The Italian cities wanted to break free of the Holy Roman Empire. That meant denying all the contributions to civilization promoted by forward-thinking emperors such as Charlemagne or Ottos I, II, and III (patrons of the Scientist Pope), as well as those of the Church itself. Petrarch and his fellow humanists saw no contradiction in the fact that all of the ancient “letters, arts, and philosophy” they “discovered” had been copied, and so preserved, in the scriptoria of monasteries and cathedrals through the thousand years of the so-called darkness.

A clearly spherical earth, in the mid-14th century Bible Historiale of John the Good (BL MS Royal 19 DII).

Skip to the American writer Washington Irving (1783-1859). In his time, studying the Middle Ages was considered “a ridiculous affectation in any man who means to be useful to the present age,” according to Henry St. John Bolingbroke, whose political writings influenced Thomas Jefferson, among others.

This attitude made it easy for Washington Irving, in The Life and Voyages of Christopher Columbus, to rewrite the discovery of the New World in 1492. In the 1820s, having just published the stories “Rip Van Winkle” and “The Legend of Sleepy Hollow” to popular acclaim, Irving went to Spain, where he was given access to original documents about Columbus. Finding the truth a little “dry,” in his words, he decided his hero’s story required more dramatic tension. Writes Russell: “It was he who invented the indelible picture of the young Columbus, a ‘simple mariner,’ appearing before a dark crowd of benighted inquisitors and hooded theologians at a council of Salamanca, all of whom believed, according to Irving, that the earth was flat like a plate.”

What in fact they believed—and the original records of the council still exist—was that Columbus was fudging his numbers. Using the standard method given in medieval geometry textbooks—and on the map from before the year 1000—the Council of Salamanca calculated the circumference of the earth to be about 20,000 miles (it is actually about 25,000 miles) and the distance between one degree of latitude or longitude at the equator to be 56 2/3 miles (it is actually 68 miles). Columbus thought the earth was much smaller. He said a degree was 45 miles and the span of ocean between the Canary Islands and Japan only 2,765 miles—twenty percent of the actual figure. If he had not providentially bumped into America, Columbus would—as the experts in Salamanca believed—have run out of food and fresh water long before he reached Japan. Columbus, says Russell, had “political ability, stubborn determination, and courage” on his side. His opponents had “science and reason” on theirs.

Washington Irving took science and reason and gave them to Columbus—and it was Irving’s version of history that became common knowledge. Why? Americans, says Russell, “wanted to believe that before the dawn of America broke, the world had been in darkness.”

You can see more medieval images of a round world on Donna Seger’s blog, Streets of Salem: She writes (sadly): “every year I poll the incoming freshmen in my World History class about what they were taught in primary and secondary school and every year more than half of them raise their hands in support of the medieval flat earth.”

Join me again next Wednesday at for another writing adventure in Iceland or the medieval world.

Wednesday, September 12, 2012

The Pace Gene

Icelandic horses are famously either four-gaited or five-gaited. They can walk, trot, and canter (or gallop), like all horses can. But Icelandics can also tolt (a kind of running walk) and pace, which is a racing gait. No other breed of horse can coordinate the movement of its legs in so many different ways, I discovered when researching my book A Good Horse Has No Color in the late 1990s. Recently I learned exactly why:

In August, a group of Swedish, Icelandic, and American scientists published an important scientific paper in the journal Nature identifying the genetic mutation that causes Icelandic horses to tolt and pace. See

Led by geneticist Leif Andersson of the Swedish University of Agricultural Sciences and Uppsala University, the group first compared the genes of 30 four-gaited Icelandic horses to 40 five-gaited Icelandic horses. They found “a highly significant association between the ability to pace and a single nucleotide polymorphism” or SNP (pronounced “snip”) mutation on one chromosome in the horse genome.

They confirmed that association by testing an additional 352 Icelandic horses (both four-gaited and five-gaited), along with 808 horses of other breeds.

The SNP mutation occurred in a gene named DMRT3. Investigating this region in mice, the researchers discovered that it controls leg movement. The gene is expressed in the spinal cord, producing neurons that affect length of stride, swing time or flexion, and both front-back and left-right coordination.

To pace, an Icelandic horse must possess two copies of the mutant DMRT3 gene. To tolt, a horse needs one copy. 

You can watch an Icelandic horse tolt on YouTube, courtesy of my friend Stan Hirson:

To understand what the Nature paper meant, I needed to review some terminology. Fortunately, I had learned a lot of that when coauthoring the book Mendel in the Kitchen: A Scientist’s View of Genetically Modified Foods with Penn State geneticist Nina Fedoroff in 2004.

The genome, I recalled, was the horse’s complete set of genes, packed into the chromosomes inside each of its cells. Genes are made of DNA, a long molecule that forms a double helix, looking like a twisted ladder. DNA itself is made up of four small molecules, the nucleotides adenine (known as A), cytosine (C),  thymine (T), and guanine (G).

In the 1960s, scientists learned how to read the DNA code. Each sequence of three letters, each codon, such as GAG or GAA or AAA, stands for an amino acid (except for three codons, which instead mean “stop”). When the code is read, the cell’s machinery links the specified amino acids together into a chain, which is then folded up to become a functioning protein. Each protein made by the body has its corresponding DNA code—a gene.

There’s more than genes in a genome, if by gene we mean the DNA sequence that codes for a protein. Many DNA sequences don’t code for proteins. Instead, they control when and where in the body certain proteins are made. Still other sequences are thought to be useless junk, though scientists keep finding uses for more and more of this junk, as the recent ENCODE study shows. See:

An Icelandic horse showing trot.

But the mutation that allows Icelandic horses to tolt and pace is a relatively easy one to understand. A SNP mutation, or single nucleotide polymorphism, means that one nucleotide (one A, C, T, or G) in the DNA sequence of the DMRT3 gene was wrong. The three-letter codon that this one nucleotide was part of should have coded for an amino acid. Instead, it said “stop.” The mutant form of the gene found in Icelandic horses is significantly shorter than the wild type found in three-gaited horses.

In fact, all gaited horse breeds tested, including the Icelandic horse, the Kentucky Mountain Saddle horse, the Missouri Fox Trotter, the Paso Fino, the Peruvian Paso, the Rocky Mountain horse, the Standardbred, and the Tennessee Walking horse, had the short, mutant type. All three-gaited breeds—Arabians, Gotland ponies, North-Swedish draft horses, Przewalski’s horses, Shetland ponies, Swedish Ardennes, Swedish Warmbloods, and Thoroughbreds—had the long, wild type.

Now the terms “wild type” and “mutant” are value-laden. Geneticists used to use “wild type” to refer to the typical form found in nature. But it’s now accepted that genes can come in many different forms in a single species without any one of them being more typical than another.

In this study, the researchers seem to have assumed that, since all horses can walk, trot, and canter/gallop, these gaits are more typical. The fact that the Przewalskis horsethe closest wild relative of the domesticated horsehas only three gaits supports this conclusion. The researchers therefore assigned the label “wild type” to the long version of the gene, the one that produces three-gaitedness.

But the reverse could be true. And even if the Icelandic horse’s shorter DMRT3 gene is not the wild type, the mutation must have happened very early in the history of horse evolution: When anthropologist Mary Leakey uncovered the tracks of three 3.5-million-year-old equids in East Africa, she found their footfalls to match those of a tolting Icelandic horse traveling at ten miles an hour.

The same horse showing canter.

Horse historians, especially those (like me) within the Icelandic horse community, have long argued that gaitedness was bred out of horses since medieval times, not bred in.

As I wrote in A Good Horse Has No Color, the first Icelandic horses were bred for strength, speed, color, and a smooth, untiring traveling gait. Few of Iceland’s bridle paths, though ancient and well-worn, are smooth and even. Interrupted by birch brush and roots, they cross farm fields heaved and hummocked by frost, pocked and pitted with bogs. They angle up and around precipitous slopes, wind along rocky rivers, or pick their way through lava wastes. Yet even today, when riding fast and far is only a pleasure, not a necessity, Icelandic horses routinely cover thirty miles a day. On one trek organized in 1994, one thousand kilometers—six hundred miles—were ridden in two weeks, an average of over forty miles each day.

When Iceland closed its borders to the importation of horses sometime in the Middle Ages (no medieval source gives us an exact date), today’s fine distinctions between fast tolt, slow tolt, trot-tolt, pacey-tolt, traveling pace, and piggy pace were unknown. A good horse was comfortable to ride all day, which meant it possessed some mid-speed gait other than a jarring, jouncing trot.

In the rest of medieval Europe, such a horse was known as an ambler, palfrey, or jennet, and would be ridden by ladies or noblemen or knights not in armor. The word “ambler” comes from the early Roman ambulator, or walker, while a trotting horse in these same documents is called a cussator or cruciator, a “tormentor” or “crucifier.” “Palfrey” derives from the Greek parippi or the Celtic paraveredus, both meaning a horse used for long journeys. The jennet was originally a particular breed out of Spain, known for its easygoing slow pace.

When roads became widespread during the Renaissance and carriages were the noble way to travel, selective breeding for smooth-gaited riding horses declined. People bred for trotters, faster and with more stamina when under harness. Only in the roadless outposts of European culture were the smooth, lateral gaits like the tolt retained, producing, in the New World, such breeds as the Tennessee Walking Horse and the Peruvian Paso.

The same horse showing tolt.

The Icelandic horse experts I consulted in the 1990s, while writing A Good Horse Has No Color, assured me that the ability to tolt was genetic and that it depended on the pace. According to one, “It is part of the quality of the trait, how easy it is to breed it. Well-bred Icelandic horses should therefore be almost self-trained to tolt.” Said another, “Not all horses have pace worth showing, but it is considered good for the tolt if the horse has some pace. It is thought that without breeding for pace, the tolt would be lost.”

The Nature study proves they were right. If you breed a mare and a stallion who each have only one copy of the short DMRT3 gene, you can get a foal that has no copies of it: This foal will be three-gaited. That’s why this study is so important to Icelandic horse lovers. It tells us exactly how to preserve what we love best about our breed: the gaits.

For breeders who want to know in advance of training and evaluation if a foal is five-gaited, a simple DNA test is already available from Capilet Genetics: The company notes, however, that “the quality of the pace is a quantitative trait that is determined by many genes working together and the environment (training).”

In other words, the short DMRT3 gene is necessary, but not enough for true flying pace. The Swedish study found that 31 percent of the horses considered four-gaited were genetically five-gaited: They had two copies of the short DMRT3 gene. The classification was done by Thorvaldur Arnason of the Agricultural University of Iceland in Borgarnes, based on WorldFengur records. Their pace was simply not good enough for them to show it in competition.

The same caveat holds for the tolt. Without one copy of the gene, your horse cannot tolt. But genetics alone cannot explain how well your horse tolts.

The horse in the gait photos above is Parker fra Solheimum, a first-prize Icelandic stallion owned and ridden by Sigrun Brynjarsdottir. Visit them at http://usicelandics.comOn the US Icelandic Horse Congress’s website (, you learn more about Icelandic horses. Or take a virtual ride on my friend Stan Hirson’s video blogs, and Life with Horses ( Stan's beautiful video of an Icelandic horse tolting is also available there.

Join me again next Wednesday at for another adventure in Iceland or the medieval world.