Who was actually carried across the Atlantic—at what age, and whether male or female—is for Geggus a question with consequences on both shores, bearing on the societies captives left and those they entered. He pursues it through the French trade, using two bodies of evidence.

The first covers some 177,000 captives shipped between 1714 and 1792, counted from the ship-by-ship inventory of French slaving voyages that Jean Mettas and Serge Daget assembled as the Répertoire des expéditions négrières. The second draws on close to 400 estate inventories listing over 13,300 African-born people on Saint Domingue plantations between 1721 and 1797.

Measured against what was already known, the figures show how sharply the mix shifted over the century and from one point of embarkation or arrival to the next, and point to the market pressures deciding how many men, women and children were sold. Consistent contrasts emerge among African ethnic groups and among buying colonies, several previously unremarked.