Tuesday, August 9, 2022

A triumph of science and legend

Chances are that you've never heard of Puerto Real. If you have, you may be thinking of the port city in the Andalusia region of Spain or, more obscurely, of a barrio in Vieques, Puerto Rico. But there was, once upon a time, another Puerto Real...

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The land of high mountains 

The Taíno Indians called their island Ayiti, the land of high mountains. A Genoese navigator landed on Ayiti in December of 1492, with unfortunate consequences for the Taíno. You've heard of this newcomer, and if you noticed the date you've already guessed his identity. 

In his native Genoese his name was Cristoffa Corombo, in Italian it was Cristoforo Colombo, and in Spanish Cristóbal Colón. The Spanish name is pertinent because, having twice lobbied unsuccessfully for patronage from the king of Portugal, and his envoy to the king of England having been waylaid by pirates, he now found himself in the employ of Ferdinand II of Aragon and Isabella I of Castile. Ferdinand and Isabella had recently united their kingdoms through marriage, and then conquered the Emirate of Granada. While consolidating their control over what would eventually become Spain, "the Catholic Monarchs" were perfectly willing to let Colón conquer the New World for them.

Cristoffa Corombo may have been the child of a lawful union, but Cristóbal Colón was a thoroughgoing bastard bent on riches; his agreement with Ferdinand and Isabella stood to make him fabulously wealthy. When Colón arrived on Ayiti, he renamed it La Isla Española; the new name was eventually rendered as Hispaniola. (And still later, the western third of Ayiti became the nation of Haiti.) Spanish towns were founded all over the north coast of "the Spanish Island" while its Taíno population was subjected to encomienda and decimated by smallpox, and as the transatlantic slave trade began with the first license to import African slaves being granted to the governor of Hispaniola, Nicolás de Ovando, in 1501.

One of those early Spanish towns was Puerto Real, established in 1503 and populated by Spaniards, Africans, Taíno, and—important to our story—Spanish cattle. Cattle and copper were the economic mainstays of the Puerto Real economy, and of the two cattle may have been the more important—both for their meat and their hides. Beef would have formed a major component of the local diet, but leather travelled better and was therefore more valuable in trade. And trade, at least for a while, was considerable: until the founding of Havana, Cuba, in 1515, the last port of call for ships leaving the Americas for Spain was the next town over from Puerto Real: Puerto Plata. (For a modern equivalent, think of the combined port of New York, NY and Newark, NJ.) A lot of cows, or their component parts, shipped out through Puerto Real and Puerto Plata.

Not all of this trade, however, was sanctioned by the Castilian crown. Especially after the opening of Havana, many of the ships visiting Puerto Real and its sister city weren't Spanish at all; Portuguese, Dutch, French, and English captains were also interested in beef, leather, and copper, and the locals not necessarily averse to ignoring the official monopoly held by the Casa de Contratación

Then, as now, monopolists liked their monopolies, and governments liked their taxes. This unregulated trade, combined with piracy (to the extent that that distinction can even be made), eventually led the Castilian crown to order Puerto Real abandoned in 1578. Following up on that order, the Spanish authorities actually destroyed most of the town the following year, though a few squatters hung on amidst the ruins. Finally, in 1605, the Spanish abandoned the entire western third of Hispaniola, withdrawing all protection for anyone living there, and the land that would eventually become Haiti was almost entirely depopulated, except for buccaneers (most of them French) who ventured into the backcountry to hunt the now-feral cattle left behind. Tropical vegetation reclaimed the ruined towns, and eventually Puerto Real was forgotten. 

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The outlier

Nicolas Delsol is an anthropologist associated with the Florida Museum of Natural History and working on his Ph.D. at the University of Florida. His research concerns the development and domestication of cattle in the Americas, and to that end he studies bones recovered from middens at archaeological sites—including teeth from Puerto Real, which was rediscovered in the 1970s and subsequently excavated by Kathleen Deagan, also at the Florida Museum. 

Delsol was extracting and analysing mitochondrial DNA (mtDNA) from cow teeth recovered from Puerto Real. Unlike nuclear DNA, which comes from both parents in species with sexual reproduction, mtDNA is (generally) inherited only maternally. It is therefore not "shuffled" with each generation; this relative stability makes mtDNA useful for tracing lineages back through time. Similarities and differences in mtDNA can be used to assess the degree of relatedness within a population of animals, as well as phylogenetic relationships among different populations—helpful for a researcher, like Delsol, trying to recreate a sort of bovine family tree.

Among Delsol's Puerto Real data, he found an outlier—a very serious outlier, bearing little relation to his other samples. Upon closer examination, what had been assumed to be yet another fragment of cow tooth amidst vast piles of cow teeth turned out to be a small piece of molar from a different species: a horse.

There are two approaches a researcher can take upon discovering such an anomaly. The fly-in-the-ointment approach is simple: chuck it out and focus on the task at hand. Nicolas Delsol, however, is going places, an academic's academic, and opted for the lemonade approach: he assembled a team, further analysed the new data in a different context, and wrote up their results. 

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Conquistadores y caballos

The first horses, exemplified by the genus Eohippus, appear in the fossil record of the early Eocene period, about 52 million years ago. They seem to have originated in North America, and much of their subsequent development took place here as well. Well-known palaeontological sites such as La Brea in California, Hagerman in Idaho, and Ashfall in Nebraska all include equine fossils. But horses were extirpated from the Americas during the Pleistocene, some ten to twelve thousand years ago, likely the result of climate change resulting in vegetational shift, overhunting by newly-arrived human populations, or some combination of those factors. They were not seen again until 1493, when Columbus made his second voyage and planted a herd at La Isabela on, you guessed it, Hispaniola. 

The Hispaniolan herd expanded through both natural reproduction and the continued importation of horses from Spain, until Nicolás de Ovando declared, in effect, That's enough horses, thanks. Keep the Africans coming. As the Spanish conquistadores expanded into other parts of the Caribbean and then the mainland, horses from Hispaniola (and smallpox) went with them. As Delsol and his collaborators note, "One of the most iconic episodes of equid introduction in the Americas is the arrival, in 1519, of Hernán Cortés’ 16 horses on the Mexican Gulf coast, contributing to the military conquest of Mexico. These animals were so essential that Spanish chronicler Bernal Diaz del Castillo gave a detailed description of each animal, with its name and appearance." Coronado, de Soto, and others relied on their mounts as well, and Spanish horses in various places went missing—lost, stolen, or captured in battle—leading eventually to populations of mustangs and the Native American horse cultures of the Great Plains.

As the other European powers established a North American presence, they brought their own horses, notably breeds from Great Britain and the Netherlands. Quoting again from Delsol et al., "Horse breeding rapidly became an important activity in some British colonies. By the 18th century, New England horses were a major export to the Caribbean where the sugarcane industry was in critical need of draft animals." The mingling of horses from different locations and lineages, whether deliberate or unintended, continues to this day. And mtDNA is one of the means by which the history of the horse can be inferred. 

Formal analysis by two of Delsol's colleagues, Brian Stucky and Jessica Oswald, compared the mtDNA of the Puerto Real specimen to an existing dataset of equine mtDNA from around the world. A reasonable assumption could be made that the Puerto Real specimen would be closely linked to present-day horses from the Iberian Peninsula—that is to say, Spain. However, no such relationship was observed. Instead, the closest affinity was with another sample from the Americas, though not from the Caribbean. 

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A dark and stormy night 

Edward Bulwer-Lytton would be proud. Bulwer-Lytton was the writer who opened a book with "It was a dark and stormy night," later co-opted by Madeleine L'Engle and by Snoopy ("Here's the world-famous author...") for its cliché value. But in truth, a dark and stormy night does offer great dramatic value, and Marguerite Henry's best-known novel opens with a storm off the Atlantic coast. A Spanish galleon founders and then breaks open on the shoals near Assateague, a long barrier island off the coast of Maryland and Virginia, spilling its cargo of Spanish horses into the sea. Though all hands are lost, the horses swim to safety, making landfall on the beach of Assateague. And there they persist, for generations:

The seasons came and went, and the ponies adopted the New World as their own. They learned to take care of themselves. When summer came and with it the greenhead flies by day and the mosquitoes by night, they plunged into the sea, up to their necks in the cool surf. The sea was their friend. Once it had set them free. Now it protected them from their fiercest enemies.

—Marguerite Henry, Misty of Chincoteague

More than anything, it was Marguerite Henry's book, and the 1961 movie based on it, that brought the islands of Chincoteague and Assateague, and their ponies, to widespread attention. I was fortunate enough to grow up a frequent visitor to the islands—my parents' ashes are now scattered there—and the wildlife there, horses included, has been an important part of my identity for my entire life. 

Assateague horses or Chincoteague ponies—both names are valid—are a recognised breed, and there are two widely accepted but competing theories for their origin. One holds that the population originated with the horses of English colonists being pastured on the islands, either for the free grazing or to avoid taxation on the mainland, and eventually becoming feral. (Somewhat confusingly, the place name "Chincoteague" originally applied to a settlement on the mainland opposite the island as well as to Chincoteague Island itself, and for much of the colonial period the island was sparsely inhabited if at all.) I'll call this one the Chincoteague pony hypothesis, since the animals actually originate from Chincoteague. 

The second theory, of course, is the shipwreck legend, more or less as presented by Marguerite Henry. In this scenario, the animals really are Assateague horses, living free on the islands ever since their escape from the hold of one or more Spanish ships. Proponents of this view point out that, while the Spanish did not settle the mid-Atlantic, they certainly did explore the region.

When Marguerite Henry visited the islands on the advice of her editor, she would likely have heard both of these origin stories. Ask yourself: as a storyteller, which would you pick? As a kid, I bought into the shipwreck story with every fibre of my romantic being. But as an adult, I had to concede that the historical record, which includes no mention of feral horses by the first English settlers to the area, made the Chincoteague hypothesis more likely if less romantic. 

But now along come Nicolas Delsol and his colleagues with their mtDNA analysis, and it turns out that the closest match to the Puerto Real specimen is not a horse from present-day Castile, or anywhere else on the Iberian Peninsula, but an Assateague horse. 

By the 1920s, the Assateague herd was showing signs of inbreeding depression, and fresh bloodlines were introduced. Welsh and Shetland ponies, mustangs from BLM land out west, even a few Arabians were crossed in to improve the breed. Horses are polygynous breeders; introducing just a few stallions would have been easier than introducing a larger number of mares, and in the case of the Arabians at least we know that's how it was done. But while outside stallions would have increased the overall genetic diversity of Assateague horses, they would have had essentially no impact on the mitochondrial DNA. And even if a few mares were brought in, they would have a more limited impact on the overall makeup of the population. 

What the Delsol paper tells us is that Assateague has been a time capsule of sorts; that while the horses in present-day Spain have drifted considerably apart from the type found in late fifteenth/early sixteenth century Spain and Hispaniola, some of the horses on Assateague today (quite likely the majority, though the limited data do not support such a conclusion) bear close resemblance. They are Spanish horses, not English, and that enhances the possibility that they did emerge heroically from the surf, with Assateague sand under their hooves, as they discovered freedom in their New World.

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Wednesday, August 3, 2022

Not singing, just hot

Grey catbird at Long Pine Creek. Temperatures in northern Nebraska that week were comparable to Tucson, and I think a degree or two higher. Plus humidity.

Tuesday, August 2, 2022

House wrens

House wrens on Smith Falls Creek. Photos by Jessa.