In Africa, where domestic slavery was the predominant form of slavery, female slaves were usually favored as they were perceived as being more easily-controlled and less likely to rebel. In the Americas, however, where productive slavery was more prevalent, male slaves were preferred due to the physical intensity of the labor and the perception that they were more likely to survive seasoning or acclimatization to the new environment (in reality, male slaves in the New World had a much higher mortality rate than female slaves).
It is often quoted that slavers aimed to capture two male slaves for every female slave, yet most sources suggest that this target was rarely met. The averages shown here suggest that the gender ratio among slaves was around 179 males for every 100 females, although the difference varied by region, national carrier and century; for example, a much higher share of male slaves was transported to Cuba in the 19th century, than those transported to British Caribbean colonies in the 18th century. Because of these variations, and the lack of gender ratio from several of the earliest and busiest routes (namely Portuguese voyages to Brazil, which was the most common destination for slaves during the transatlantic slave trade), historians are often reluctant to make overall estimates for the gender ratio during the transatlantic slave trade. Nonetheless, a ratio of 170 to 180 males per 100 females is the most common consensus given among modern historians.