The Ecological Atlantic

The Ecological Atlantic

J.R. McNeill

I. Introduction

This presentation offers a vision of the Atlantic world (c. 1450-1850) in which pigs and plasmodia share the stage with people. In environmental history, nature is not merely the backdrop against which human events play out. It provides unconscious participants in the drama, who, although they left no memoirs or documents, took part in shaping human history.

Environmental historians have already laid some useful foundations for an ecological history of the Atlantic world.1 But whereas historians have already tried to synthesize environmental histories of some other sizable bodies of water, including the Pacific Ocean basin, to date no one has attempted this for the Atlantic. The macrohistories of the Atlantic world ignore ecological considerations.2

II. Approaches

One might approach the goal of a general environmental history of the Atlantic any numbers of ways. One could divide the whole basin up regionally, in order to recognize the diversity in ecologies and histories in places as different as Greenland and Guyana. That would of course weaken any sense of the Atlantic as a whole, as a coherent space in its own right. Alternatively, one could begin with commodities that have helped to shape the environmental history of the Atlantic: sugar, silver, codfish, beaver fur, brazil nuts, cattle hides and so forth. Or one could turn to cultural processes, the transfer of new ideas about farming, hunting, health, and so forth from one part of the basin to another. One might, instead, begin with chronology, and suggest an Age of Epidemics, an Age of Silver, and Age of Migration or an Age of Slavery. All of these have their merits.

I will however not take a consistent approach, but instead shift this way and that, like a ship tacking into the wind. What follows, then, is an idiosyncratic look at the ecological Atlantic, 1500 to 1850, emphasizing climate change, an updated version of the Columbian Exchange, and the creole ecology of the plantation system.

III. Pan-Atlantic Environmental History

The variety of the Atlantic basin was of course so great that few features, few processes, can properly speaking be considered pan-Atlantic. However, climate change is one of those.

Climate

Climate change affected the entire Atlantic world, the islands and the ocean itself, not just its continental coasts (the circum-Atlantic). The centuries between 800 and 1250 were comparatively warm and wet in the North Atlantic, encouraging settlement of northern islands (such as Iceland and Greenland, and thickening settlement in Europe and especially eastern North America. There the favorable climatic moment coincided with the arrival of new crops including maize, beans and squash, the three sisters of Mesoamerican agriculture. They provided a much more abundant and reliable food supply in landscapes from Georgia to Quebec – as long as the favorable climate lasted.

Those same centuries in West Africa seem to have been dry ones, a situation that in the Sahel zone permitted horse-breeding, cavalry-based political power, and a temporary surge of empire building that paralleled what equestrian peoples were then doing in East Asia, Central Asia, and north India. In West Africa, the rise of ‘horse power’ made slave-raiding easier, and fed many thousands of unfortunate souls into the trans-Saharan slave trade to North Africa and Egypt.

This period, 800-1250 helped set the stage for some of the dramatic turbulence of Atlantic history after 1500, by boosting population and extending settlement widely, and intensifying West African slave-raiding.

The climate shifted after 1250, perhaps triggered by a gigantic volcanic eruption in 1258 or 1259. Throughout the northern hemisphere, temperatures turned colder and the weather dryer. The period between 1450 and 1800 included the coldest decades of the Little Ice Age. The Little Ice Age (LIA) lasted from roughly 1300 to 1850, and reduced average temperatures by about one degree Celsius in the northern hemisphere, and more in northern Europe (where the data are best). Its coldest decades came in 1590-1610, the 1640s, 1690s, and 1780s, with a long chilly spell, known as the Maunder Minimum, around 1645-1715. Throughout, it brought expansion of glaciers in the north and in high mountains, occasionally scraping villages away and covering upland pastures. The Ebro in Spain froze over in wintertime. The LIA shortened the growing season in high latitudes, with occasionally disastrous consequences in places such as Sweden, Scotland, and along the St. Lawrence, where in the best of circumstances climate made grain farming marginal. The onset of colder conditions may have helped end the Norse settlement of Greenland around 1450 (although this is disputed). In the 1750s, Iceland’s harbors disappeared within a ring of ice, fishing became difficult, farming nearly impossible, and a local population crash (15%) followed. Colder temperatures of only 1-2 degrees C in the middle latitudes (30-45 degrees North) would reduce grain yields by 10-50%, leading to price spikes, hunger and starvation. On the more cheerful side, wintry scenes of peasants frolicking on ice enriched Dutch landscape painting, and especially dense maple, willow, and spruce from the cold decades of 1660-1720 allowed Stradivarius to make his glorious violins.7

In warmer latitudes the Little Ice Age was often a big drought age. With less evaporation due to cooler air, rainfall diminished, and many—not all--of the regions prone to drought felt it more often and more severely. Central Mexico, for example, was scorched by drought, which may have set off epidemics in the form of rodent-borne disease and sharpened conflicts over irrigation. In West Africa the southern fringe of the Sahara moved southward, reducing densities of both bush and tsetse fly, thereby expanding the belt in which horses could survive. This in turn opened new scope for equestrian slave-raiding and state-building, once again severely punishing the populations without protection from cavalry. Correlations between drought and expanded slave raiding seem to exist in Angola too, where major droughts occurred especially in the 1640s . On a smaller scale, if the tree rings are to be trusted, Walter Raleigh’s effort to colonize the (water-scarce) Outer Banks of North Carolina in 1585-6 coincided with the deepest drought of the past 800 years. Even had all else gone right with the Lost Colony, this alone might well have sealed its fate. The early settlers at Jamestown had luck almost as bad, landing in the midst of the driest seven-year spell in the last 770, which contributed to their many travails.8

The ocean itself felt effects from the LIA. Shallow estuaries reflected the variations more than did deep water. The average temperature of Chesapeake Bay, for example, fell by as much as 2 to 4 degrees Celsius in the depths of the LIA, playing havoc with its rich marine life. It froze over from time to time in the 17th century, which has not happened for at least 150 years. Reef waters off the Puerto Rican coast likewise seem to have been 2-3 degrees C cooler than today during the cold intervals of 1700-15 and 1780-85. Codfish, which are exquisitely sensitive to temperature, probably migrated southward during the LIA, attracting fishermen from Britain, France, Portugal, and Spain to the more welcoming shores of New England and Nova Scotia during the late 15th and 16th centuries. It is also likely, although uncertain, that hurricanes were fewer and weaker during the LIA, making shipping slightly less hazardous.9

The LIA was pan-Atlantic, although its effects and timing varied from place to place. On balance it seems to have been stronger in the northern hemisphere than in the southern. That, however, may be an impression left by paucity of information.10

Tumult, Hybridity and Creole Ecology

A second pan-Atlantic feature was tumult. Ecological history, like biological evolution, proceeds at a variable clip, with periods of stately serenity punctuated by hurricanes of creative destruction. In the Atlantic world, while of course things changed in the millennium before 1450, they changed far more and far faster in the few centuries following. That is because, as Alfred Crosby explained, the traffic after 1492 brought together biological provinces that had been separated by ocean for 200 million years. In the blink of an eye, what had long been put asunder (by plate tectonics) was united. American ecosystems, recently destabilized by the first human occupation beginning roughly 14,000 year ago, now felt another shakeup. Squadrons of invasive species were loosed upon each participating continent, some of which succeeded gloriously in their new homes. Several native species went extinct. The history of life on earth has few if any parallels.11

The cultural processes that historians now describe with the word ‘hybridity,’ had parallels in ecology—hence my appropriation of the term. This is most obvious in the human realm, where populations of mestizos, métis, and mulattoes resulted from the encounters among Amerindians, Europeans, and Africans. Genetic reshuffling took place as well among other species from carp to hawks. Most of this was accidental, but human intention was involved as well, especially with dogs. Thus several ‘hybrid’ species emerged in the Atlantic world after 1492, and still more hybrid ecosystems. Even without genetic intermixing, where species formerly an ocean apart commingled they remade environments, producing a ‘creole ecology.’ Such recombination, on the genetic and ecosystemic level, happens all the time, but rarely with the fury that characterized the Atlantic after 1492.

IV. The Columbian Exchange (Updated and Augmented)

In 1972 Alfred Crosby introduced the concept and phrase ‘The Columbian Exchange.’ It gradually colonized the lexicon of historians and became a routine expression used to denote the massive biotic exchange between the two sides of the Atlantic in the centuries after Columbus. A menagerie of animals, plants, and microbes traveled on the ships of Columbus and his successors as they criss-crossed the Atlantic. Crosby could not quite do justice to the African roles in the process, which decades of subsequent Africanist historiography have illuminated more clearly.12 Here I will try to include the African dimensions as well as the American and European ones.

The Pathogen Exchange

First the microbes. Amerindians in the 15th century did not live especially long or healthy lives, at least to judge by the skeletal evidence. In South America there was Chagas’ disease and leishmaniasis, carried by insects. In North America, Rocky Mountain spotted fever and Lyme disease, both tick-borne. Amerindians may have had to deal with typhoid, syphilis, and almost surely tuberculosis. Those communities that took up maize in preference to other foods seem to have grown more numerous and less healthy, as maize is excellent at turning sunshine into calories but poor as a source of vitamins. But they would soon have reason to look back on the 15th century as a golden age of health.

Amerindians did not have the acute infections sometimes known as the ‘crowd diseases.’ These are almost all derived from pathogens of herd animals of Eurasia and Africa. With animal domestication, and millennia of living cheek by jowl with pigs, camels, dogs, ducks and all the rest, humans came to host a welter of highly infectious and often extremely lethal diseases: smallpox, measles, influenza, whooping cough, mumps and a few lesser ones. These all spread from human to human easily, and thus wherever trade, travel and contact prevailed so did these diseases. They usually appeared as searing epidemics, but once they had infected all available people, they ‘burned out’ and disappeared for years, until a new population of susceptibles grew up. Eventually, where populations were large and dense enough, they became childhood diseases which everyone encountered in the first few years of life, and the survivors carried resistance or immunity thereafter, sometimes, as with smallpox, lifetime immunity. By the 15th century all the densely settled parts of Eurasia and probably most of Africa north of the Kalahari hosted most of the crowd diseases most of the time. Thus most adults carried a hard-won portfolio of immunities and resistance. Amerindians were innocent of these infections, because their ancestors came to America 14,000 years ago, before any animals other than dogs had been domesticated, and before any of these pathogens had evolved into human parasites.

Amerindians also did not have a handful of infections confined to Africa. Microbial life in Africa had millions of years to co-evolve with humans and hominid ancestors, far longer than anywhere else. Thus Africa presented an especially rich disease environment, including yellow fever, dengue, filiariasis, hookworm, falciparum malaria among many others. By contrast, microbial life in the Americas had had only 14,000 years or so to ‘figure out’ how to exploit the niches presented by human bodies, and far fewer had done so.

Thus calamity struck soon after Columbus crossed the ocean. Despite the difficulties of getting microbes across the sea, eventually all the crowd diseases and all the aforementioned African infections made it to the Americas. There no one had any resistance or immunity to them, and so adults died as easily as children. Fishermen chasing the cod probably brought some of the crowd diseases to the Amerindians of northeastern North America (conceivably Vikings had done so earlier too). Columbus and those trailing in his wake introduced and re-introduced them to the Caribbean. Once the slave trade from West Africa geared up, by 1550 or so, the African infections began to add to the Amerindians’ calamity. The importance of falciparum malaria and (though it may have arrived only in the 1640s) yellow fever is reflected in the far greater depopulation of lowland regions in Atlantic America as opposed to higher elevations in Mexico and the Andes where indigenous people (and therefore culture) survived in larger proportion.