Sloane Collection-Natural History Museum: Cocoa plant brought back from Jamaica in 1689 by Hans Sloane. Illustration by Everhardus Kickius.

Hans Sloane collected this specimen of cacao in Jamaica in the 1680s. Sloane often collected on or near slave plantations, taking advantage of slavery’s infrastructure to advance his science.


Historians expose early scientists’ debt to the slave trade

At the dawn of the 1700s, European science seemed poised to conquer all of nature. Isaac Newton had recently published his monumental theory of gravity. Telescopes were opening up the heavens to study, and Robert Hooke and Antonie van Leeuwenhoek's microscopes were doing the same for the miniature world. Fantastic new plants and animals were pouring in from Asia and the Americas. But one of the most important scientists alive then was someone few people have ever heard of, an apothecary and naturalist named James Petiver. And he was important for a startling reason: He had good connections within the slave trade.

Although he rarely left London, Petiver ran a global network of dozens of ship surgeons and captains who collected animal and plant specimens for him in far-flung colonies. Petiver set up a museum and research center with those specimens, and he and visiting scientists wrote papers that other naturalists (including Carl Linnaeus, the father of taxonomy) drew on. Between one-quarter and one-third of Petiver's collectors worked in the slave trade, largely because he had no other options: Few ships outside the slave trade traveled to key points in Africa and Latin America. Petiver eventually amassed the largest natural history collection in the world, and it never would have happened without slavery.

Petiver wasn't unique. By examining scientific papers, correspondence between naturalists, and the records of slaving companies, historians are now seeing new connections between science and slavery and piecing together just how deeply intertwined they were. "The biggest surprise is, for a topic that has been ignored for so long, how much there was once I started digging," says Kathleen Murphy, a science historian at California Polytechnic State University in San Luis Obispo who's writing a book about the topic. She adds, "There's a tendency to think about the history of science in this—I don't want to say triumphant, but—progressive way, that it's always a force for good. We tend to forget the ways in which that isn't the case."

James Delbourgo, a historian at Rutgers University in New Brunswick, New Jersey, who has written extensively about slavery and science, agrees. He argues that the belief in the progressive nature of science has made historians reluctant to take a critical look at its past. "This is a hard story for us to deal with," he says. He adds that academic specialization also prevented many people from seeing what, in retrospect, seem like obvious connections: "Slave trade historians don't know about science, and vice versa."

There’s a tendency to think about the history of science in this—I don’t want to say triumphant, but—progressive way, that it’s always a force for good. We tend to forget the ways in which that isn’t the case.

Kathleen Murphy, California Polytechnic State University

Those connections aren't just ancient history. Thousands of specimens collected through the slave trade still reside in places such as the Natural History Museum in London, and they're still used in genetic and taxonomic research. Yet few people using the collections know of their origins.

All of which casts an uncomfortable shadow on what's often viewed as a heroic era in science. "We do not often think of the wretched, miserable, and inhuman spaces of slave ships as simultaneously being spaces of natural history," Murphy writes in The William and Mary Quarterly. "Yet Petiver's museum suggests that this is exactly what they were."

Compromises to gain access to distant lands

Slavery is as old as civilization, but the transatlantic slave trade between the 1500s and 1800s was particularly brutal. Estimates vary, but at least 10 million Africans were enslaved, with roughly half dying on the way to slave ports or on voyages across the ocean. Statistics alone can't capture the cruelty and squalor of slave ships, though. Men and women were chained up for weeks in hot, filthy holds, where diseases ran rampant and punishment for disobedience was harsh. Sharks reportedly followed ships on journeys, having learned that a slave or two would probably be tossed overboard—or commit suicide—at some point.

Why did scientists align themselves with that horror? Access. European governments did sometimes sponsor scientific expeditions, but most ships visiting Africa and the Americas were private vessels engaged in the "triangular trade." That three-way exchange sent guns and manufactured goods to Africa; slaves to the Americas; and dyes, drugs, and sugar back to Europe. To gain access to Africa and the Americas, scientists had to hitch rides on slave ships. Upon arrival, the naturalists also relied on slavers for food, shelter, mail, equipment, and local transport.

France, Portugal, and the Netherlands captured and sold slaves, Murphy notes. But most historians studying science and slavery focus on Great Britain, which in the 1700s boasted the world's biggest and most powerful fleets, had adventurous scientists and collectors, and was a major participant in the slave trade. Spain controlled most of South and Central America then, but it lacked colonies in Africa and therefore couldn't import slaves directly. So it contracted that job out to various groups, including the British in the early 1700s, buying up to 4800 Africans per year.

When people were traded like goods

In the “triangular trade” of the 16th through 19th centuries, millions of people were shipped to the Americas as slaves, raw materials were transported to Europe, and manufactured goods went to Africa. The three-way trade provided European collectors access to specimens from Africa and the Americas.

Tobacco, rice, cotton Guns, textiles Sugar, molasses Africans shipped to America Colonizing nations Senegambia EUROPE Sierra Leone Windward Coast Gold Coast Bight of Benin Bight of Biafra West central Africa Southeast Africa NORTH AMERICA SOUTH AMERICA AFRICA Britain Trade routes Portugal Milllion France Spain The Netherlands 2 1 3 CARIBBEAN ISLANDS

When British slave ships arrived in Latin America, the crews had strict orders to stay at port and not poke around, mostly because Spain wanted to protect its monopoly on certain lucrative natural resources. But naturalists such as Petiver knew Spain had no way to enforce that rule—the territories had too little oversight. So they cultivated crew members to collect specimens on the sly.

Murphy's research shows Petiver employed mostly ship surgeons, who cared for slaves on the voyage across the ocean. The surgeons were scientifically educated, she says, and had plenty of free time at ports such as Cartagena, in modern Colombia, and Portobelo, in modern Panama, while their fellow crew members sold slaves and provisioned the ships. Petiver usually supplied recruits with kits that included jars for insects and brown paper for pressing plants. Compensation included books, medicines, and cash.

Strikingly, some naturalists also instructed their contacts abroad to train slaves as collectors. Slaves often knew about specimens that Europeans didn't and visited areas that Europeans wouldn't. Those slaves virtually never got credit for their work, though Petiver did offer to pay them a half-crown ($18 today) for every dozen insects or 12 pence ($7) for every dozen plants.

Petiver never collected overseas himself, but some scientists did, and they often found themselves in morally compromising positions. Henry Smeathman, an idealistic English naturalist, sailed for a slave colony in Sierra Leone in December 1771 and collected for the likes of Joseph Banks, an adviser to King George and longtime president of the Royal Society. Among other activities, Smeathman studied the massive termite mounds in western Africa, which stand up to 4 meters high. He had rollicking adventures breaking the mounds open and fending off attacks from angry, biting termite soldiers.

European scientists in South America often relied on black or native people to collect for them. In an illustration from 1806, three Africans in Suriname kill and flay a gigantic snake while a European scientist stands back and directs.


As detailed in the 2018 book Henry Smeathman, the Flycatcher: Natural History, Slavery, and Empire in the Late Eighteenth Century, by historian Deirdre Coleman of the University of Melbourne in Australia, Smeathman began his journey as a foe of slavery, vowing to tell the truth about "those little-known and much misrepresented people, the Negroes." And as a scientist, he considered himself superior to the ignorant, crude slavers he encountered in Sierra Leone. (For their part, the slavers thought him barmy for coming all the way to Africa to hunt for bugs and weeds.)

But Smeathman was utterly dependent on those men for food, protection, and transportation. He also got lonely and started to socialize with them, playing whist and backgammon and even golf on a rugged, two-hole course on an offshore island. Soon he was hunting goats and enjoying grog-soaked feasts on the beach with the slavers. By 1774, he was working for a slaving company based in Liverpool because it greased the wheels for shipping specimens; he even started to trade slaves in exchange for supplies for his expeditions. Bit by bit, compromise by compromise, Smeathman became part of the system he once despised.

Smeathman and others also relied on slavers to haul their precious specimens to Great Britain, packing them onto the same ships as enslaved Africans. (Few ships sailed straight back to Europe from Africa, so most specimens reached England via the Caribbean.) Perhaps not surprisingly, given how they treated their human cargo, the ships' crews had a spotty record in caring for fragile bugs, plants, and animal skins. If the sunlight, heat, humidity, and saltwater didn't destroy the specimens, the worms, ants, and rodents onboard usually did. Careless sailors might also smash the specimens by accident or for sport.

Of the items that arrived safely in England, naturalists were most excited about exotic finds such as ostrich eggs, Goliath beetles, butterflies, sloths, and armadillos. But the real treasures, Murphy writes, were drugs such as cinchona bark, which contains quinine, and dyes such as deep-blue indigo and bright-red cochineal. The latter, which is extracted from beetles, was worth more per ounce than silver.

Scientific studies of drugs and dyes often opened new opportunities for slave traders. Merchants eagerly sought natural resources to exploit abroad and consulted scientists about the best way to hunt for and cultivate them. Quinine and other drugs gleaned from tropical locales, Murphy notes, also helped Europeans survive there. And the safer and more profitable a colony was, the more its commercial activity, including slavery, thrived, creating new demand for slaves. Scientific research, then, not only depended on colonial slavery, but enabled it and helped expand its reach.

The tainted origins of many cabinets of curiosity

Of all the scientific fields, natural history benefited most from the slave trade, especially botany and entomology. One disciple of Linnaeus reported collecting three species new to science within 15 minutes on his first excursion in Sierra Leone. The bounty of plants astounded him.

Doctors affiliated with slavery also collected human remains. "The trade in natural curiosities was widespread, and body parts were definitely part of that," says Carolyn Roberts, a historian of science and assistant professor of African American studies at Yale University who's writing a book about the slave trade and medicine. "Doctors would send things to Britain, especially if they had a case they found interesting." Examples of interesting items included polyps cut from the hands of slaves, patches of dried skin, a fetus taken after a miscarriage, and, according to one old catalog, "stones extracted from the vagina of a negro African girle."

Those bugs and plants and bits of human beings often ended up in wealthy gentlemen's "cabinets of curiosity," jammed next to Roman coins and gems and whatever else tickled their fancy. Other specimens landed in universities or scholarly institutes.

Newton himself, who’s really the paradigm figure of an isolated, nontraveling, sitting-at-his-desk genius, had access to numbers he wouldn’t have had access to without the Atlantic slave trade.

James Delbourgo, Rutgers University

Some historians now refer to those private and institutional collections as the "big science" of their day. Scholars studied those centralized repositories and then circulated accounts of their research to other scientists. Linnaeus drew on such accounts when putting together Systema Naturae in 1735, the book that introduced his famous binomial naming system for flora and fauna.

A few physical sciences also piggybacked on the slave trade. Slave labor built the first major observatory in the Southern Hemisphere, in Cape Town, South Africa. Astronomers such as Edmond Halley solicited observations of the moon and stars from slave ports, and geologists collected rocks and minerals there.

Even a field as rarefied as celestial mechanics benefited from slavery. When developing his theory of gravity, Newton studied ocean tides, knowing that the gravitational tug of the moon causes them. Newton needed tide readings from all over the globe, and one crucial set of readings came from French slave ports in Martinique. Delbourgo says, "Newton himself, who's really the paradigm figure of an isolated, nontraveling, sitting-at-his-desk genius, had access to numbers he wouldn't have had access to without the Atlantic slave trade."

Museums grapple with the past

Many natural history specimens with ties to the slave trade eventually ended up in museums. When Petiver died in 1718, a fellow naturalist in London named Hans Sloane snapped up his collection. Sloane had collected on slave plantations in Jamaica, and he married into a slaving family whose money enabled more collecting. In 1727, he succeeded Newton as president of the Royal Society (which itself invested in slaving companies).

When Sloane died in 1753, he willed his collection, including Petiver's goods, to the British government, and it became the foundation of the British Museum in London. The museum later split into several entities. Many of Sloane's specimens went to the Natural History Museum, where they remain today. Specimens collected through the slave trade also ended up at the Oxford University Herbaria, Royal Society, and Chelsea Physic Garden, among other places, Murphy reports.

Representatives for those institutes say it's difficult to put numbers on how many of their specimens have ties to slavery. In some cases, they haven't gone through and digitized the records yet, and many old specimens have vague or fragmentary records anyway, making their provenance obscure. But documents from the 18th and 19th centuries attest to thousands upon thousands of items pouring into Europe. Smeathman alone sent 600 species of plants and 710 species of insects back to England, often with several individuals per species. (One of Smeathman's patrons complained about the glut of bugs, writing that Smeathman had sent too many to unpack: "My House could not possibly contain one half.") And although many old specimens have either disintegrated or been lost, at least some with ties to slavery probably survive in almost every institute in Europe with natural history collections dating back a few centuries.

In addition to his own collecting, Hans Sloane (pictured) bought up the collections of other naturalists, many of whom used slave ships to reach far-flung places. When Sloane died in 1753, his specimens became the founding collection of the British Museum. They later ended up in London’s Natural History Museum.


Those collections aren't just antiquarian curiosities. Scientists still consult them to construct phylogenies and do taxonomic work: Many of the collections contain type specimens, the first described individual of a species against which all other individuals are compared. The collections are also invaluable for studying plant domestication, historic climate change, and shifts in geographical distributions of species. Scientists have even extracted DNA from specimens to study how plants and animals have evolved across the centuries.

Most scientists, however, remain unaware of the origins of the collections. "Very few people think about how [specimens] were collected, whether they were collected through slave trade routes or otherwise," says Stephen Harris, a curator at the Oxford University Herbaria, which houses some of Sloane's goods. "They're simply data points."

In an email, Mark Carine, a curator at the Natural History Museum, noted that institutions such as his have a broader role than just preserving specimens. "As curators, we have a responsibility not only to care for our collections and make them available for research but also to facilitate an understanding of their significance and relevance today." He adds that Sloane's collection "is not simply a biological record; it is also a resource for understanding the social and historical context within which science developed, and we are certainly keen to continue working with researchers across disciplines to better understand this."

Still, Murphy and Delbourgo say that even some curators are oblivious to the histories of their collections, and Murphy encountered one who dismissed her work outright. Delbourgo emphasizes that his historical research "isn't an attack on museums" and that he knows museum staff are often "under-resourced and overworked." But, he adds, "Museums have been bad" about acknowledging the dubious origins of many items. "They have dragged their feet enormously."

Now that the link between early science and slavery has come to light, an important question remains: What should scientists do about it?

Historians say acknowledgment is a start: In research papers, scientists should mention how specimens were gathered. Taking the origin of specimens into account can also improve the research itself, especially given the paucity of collecting records in some cases. For example, Murphy mentions that the slave trade can help explain the geographic distributions of certain specimens. African plants, for instance, wouldn't have been collected from all over the continent, but from specific points along the coast—the ports where countries were shipping slaves.

"From a scientific point of view, your specimen is essentially a piece of evidence," Harris adds, "and the more you know about the provenance of that piece of evidence and the better understanding you have … the better you can use it within your analyses."

The connections between science and the slave trade could also feed into ongoing debates about reparations and the historical legacies of slavery. Like some U.K. organizations, U.S. universities such as Yale, Georgetown, and Brown have acknowledged how they benefited from slavery. For the most part, Murphy says, those conversations are framed "in terms of just dollars and cents, pounds and pence. Yet [the profits] can also clearly be measured in specimens collected and papers published."

Overall, she says, "Modern science and the transatlantic slave trade were two of the most important factors in the shaping of the modern world." Historians are finally recognizing that they shaped each other as well. As Delbourgo says, "We've been so negligent in bringing these histories [of slavery and science] together. We've missed that they are in fact the same history."