A bitter harvest: Slave labour and sugar on São Tomé

The first archaeological project ever mounted on São Tomé is examining a 16th-century sugar mill. Results are shedding fresh light on the origins of the tropical plantation system, which would go on to shape the Atlantic world at a terrible human cost, as M Dores Cruz told Matthew Symonds.


Volunteers to colonise São Tomé were few. After the archipelago was claimed by the Portuguese in the late 15th century, plots of land were offered to settlers, on the condition that they were developed within the next five years. It was the same formula that had been used to populate Madeira Island, about 520km west of northern Morocco, earlier in the 15th century. São Tomé was a rather different prospect, though. Located in the Gulf of Guinea, about 300km from continental Africa, it quickly gained a reputation for being both distant and deadly. But it also displayed another, far more desirable quality. It was recognised as early as 1485 that São Tomé was immensely fertile and seemed perfectly suited to sugar production. As this development could not be accomplished willingly, the authorities changed tack and effectively turned the archipelago into a penal colony. In the early years, being transported there was viewed as a delayed death sentence, with convicts forced to choose between being hanged immediately in Portugal or eking out another couple of years on São Tomé. Those sent to the island were not left to work their plots alone. Instead, the convicts were given two enslaved people: one male, for working the land, and one female, for bearing children with the convict.

The ruins of the combined mill and estate house at Praia Melão, as seen in 2023. Survey and excavation at the site are shedding new light on the origins of the tropical plantation system. 

By 1506, the suitability of São Tomé for sugar production was being put to the test. It had become home to the first plantation system ever established in a tropical climate. Sure enough, the extraordinary fertility proved a boon by providing three harvests a year. This was a rather more generous bounty than the one or two crops achieved by the competing sugar-cane growers who were already established on Madeira. Even so, the industry initially grew gradually on São Tomé. In 1517, there were just two mills dedicated to sugar production in operation. But the picture looked markedly different in the 1530s, when São Tomé established itself as the world’s biggest supplier of sugar. By 1600, as many as perhaps 120 sugar mills had been built, and plantations covered most of the suitable land, an area amounting to almost half of the largest island. Huge numbers of enslaved Africans, taken from Angola, Benin, Congo, and Sierra Leone, worked on these plantations. Between 200 and 300 of these slave labourers were required to run the largest estate on São Tomé, at a place called Praia Melão. It is a site that has recently risen to prominence once more.

The 2023 season included an archaeology field school with students from the University of São Tomé e Príncipe.

Forgotten heritage

‘I visited São Tomé in 2020’, says M Dores Cruz, of the Institute of African Studies at the University of Cologne and the Centre for African Studies at the University of Porto, ‘because I was hoping to start a project there. When I taught African Studies while I was at university as a graduate student, I became fascinated by the important role São Tomé played in the development of the plantation system. As this model was then exported to the Americas, it helped create the modern Atlantic world, whose legacy is still felt in relations of race and class, and structures of inherited wealth and inequality. But because no archaeology had previously been undertaken on São Tomé – and because there are no classified archaeological monuments – there wasn’t an obvious starting point. So I did a bit of scouting. It was during a visit to a local exhibition that I happened to see a tiny photograph showing some stones from a ruined sugar mill. I asked several people where it was, but no one knew, until eventually my colleague Nazaré Ceita said “Oh yes, that’s Praia Melão”. When I went and visited the site everything was covered in thick vegetation, but my reaction was “Holy mackerel!”, because those few stones in the photograph were part of a massive ruin. It was a combined mill and estate house, which covers about 23m by 16m, has walls standing up to 9m high, and dates to the 16th century. We’ve now completed two seasons of work there. The first year was essentially a survey of the structure, but this year we opened eight test units and had an archaeology field school with students from the University of São Tomé e Príncipe, who were participating in their first excavation.’

A plan of the ground floor (A) and first floor (B) of the combined mill and estate house, as well as an elevation of the south-west building façade. 

The building originally stood two storeys high, with the ground-floor level divided into three rooms. Of these, the largest was probably the main work area, which may have housed mill stones that were powered by water brought from a nearby stream via a mill race. Such millstones would have crushed the cane in the same way that oil was extracted from olives. An adjacent room showed signs of intense scorching and may have been used to boil the sugar. These utilitarian spaces had crudely plastered walls, which still bear traces of graffiti that were presumably created by the enslaved labour force and feature various religious symbols, including crosses. Ascending the stairs to the upper storey of the building led to another world. This area served as the living quarters for the estate owner, and was finished to a noticeably higher standard. The walls were gracefully stuccoed and featured inbuilt cabinets, while there are also traces of a balcony, presenting a range of features that were common in contemporary Portuguese houses. A generous provision of windows allowed a close eye to be kept on activity under way in the main workspaces.

A reconstruction by Luís Branco of the possible original appearance of the mill and estate house complex (left), as well as its current state of preservation (right). 

Excavations and survey in and around the mill have produced large quantities of ceramics. ‘Digging down in one of our 1m by 1m test units, we found 12kg of clay roof tiles in the first 20cm’, says Dores. ‘The total from our eight small trenches is 110.4kg. So a clay-tile roof is one of the characteristics of the building, which is quite unusual for the region, but very Portuguese. There isn’t much quality clay on the island that I could find any reference to, so presumably the tiles for this huge, heavy roof had to be imported, probably from Portugal. The second most common type of ceramic we encountered is sugar moulds. These conic earthenware ceramics had holes at the tip to allow drainage of the molasses. After the sugar-cane syrup had been boiled and purified, it would be poured into these moulds and left to harden and form the sugar loafs to be transported to Europe. We found a very large quantity of them. In 2020, I did X-ray fluorescence analysis on three of the moulds, and they came from Portugal, a finding that fits with the archaeological data from Madeira and historical data from Brazil. So far, there are very few domestic ceramics – so few that we treat them as small finds. But some ceramics that we found are very exciting. We have some decorated fragments that are clearly continental African in style. There are also large fragments of a pot crafted by a potter with very little experience and presumably being made on the estate, which is very interesting. As well as the ceramics, we have a single example of a cowry shell, which was used as currency in parts of continental Africa.’

The base of a sugar mould, as seen reused in a wall at Praia Melão. 

As well as being home to the earliest tropical plantations, São Tomé has provided some of the first evidence from this era for resistance by enslaved peoples. Chillingly, one document from 1499 considered acts of resistance by slaves to include both running away and suicide. ‘We know that the number of runaway enslaved persons was high’, says Dores. ‘Some would come back to the plantations because they probably didn’t know which foods to harvest from the forest, but others set up what are called mokambos (that is, maroon communities) in inaccessible parts of the island. This is something that I want to look into. I would like to expand the existing narrative by examining the material culture of not only the people living on the estate, but also those who toiled in the mills and those who escaped into these maroon societies. Due to the heavy vegetation and the ephemeral nature of construction, though, it will of course be very hard to find. There is one group on São Tomé today, however, the Angolar community, who are the descendants of these maroon communities. This heritage has given them a distinct identity, and they also speak a different language.’

An interior view of the work room as seen in 2020 and 2023, before (above) and after (below) most of the vegetation was cleared.


São Tomé’s dominance of the sugar trade was not destined to last. When the end came, the collapse proved rapid. ‘It was caused by several factors’, Dores points out. ‘While São Tomé has this incredible fertility – I think of it as like a greenhouse with an open roof – the climate is also very humid for most of the year. This presented a problem, because it meant that the sugar never really dried properly. The sugar that was shipped to Europe would go to Lisbon, where they had special storage facilities to dry the sugar a second time, before it was sent on to Amsterdam and other European cities. So that part of the work was doubled. Another factor for the owners was the regularity of slave revolts on São Tomé. You start getting documentary references to them in the first half of the 16th century, and there was a major revolt in 1595, when enslaved people from the plantations attacked the city of São Tomé and also burned most of the sugar mills. This episode occurred at the same time that Brazil was establishing itself as a major sugar producer on the other side of the Atlantic. Suddenly, São Tomé just didn’t look feasible anymore. So, after the revolt, most mill owners stripped out expensive equipment and moved their production to Brazil. That marked the end of the sugar cycle on São Tomé. But it also spurred an increase in production in the Americas, where plantations based on the São Tomé model would shape the Atlantic world.’

Further information
• This collaborative project has benefited from the invaluable participation of and assistance from my colleagues Nazaré Ceita, at the University of São Tomé e Príncipe, and Larissa Thomas, at Environmental Resources Management, Duluth.
• More information about Praia Melão and the plantations on São Tomé is available here: M D Cruz, L Thomas, and M N Ceita (2023) ‘Bitter legacy: archaeology of early sugar plantation and slavery in São Tomé’, Antiquity (https://doi.org/10.15184/aqy.2023.113).

All images: courtesy of M Dores Cruz