Well before the Spanish arrived in the New World, their centuries-long war against the Muslims had convinced the Spanish Crown of the need to convert non-Christians to Christianity and assimilate them into Spanish culture. So it was only natural that Spain would take the same approach with the indigenous peoples of the Americas: convert them to Christianity and introduce them to Spanish culture, while instituting a social order that separated them from the Spaniards. If only to meet its labor needs in the Americas, Spain had both economic and spiritual motivations to come to terms with the people living there.
Early Colonial Society
In the early 16th century, few women accompanied the Spanish men arriving in the Caribbean and Mesoamerica, which quickly created social conditions that favored an extensive intermixing of European and indigenous peoples. Very early on, Spanish men began living with indigenous women, taking native women as mistresses and, later, as wives. The Spanish Crown tried to engineer social policy to protect marriage between Spaniards by banning married men from traveling to the New World without their wives or, if they did go, requiring them to return to Spain or send for their wives within two years. These policies failed since the King had no way to enforce them. For a time, the Crown also prohibited unmarried women from emigrating unless they were servants or traveling with family members, leaving Spaniards in the New World with few available Spanish mates.
While the Spanish Crown struggled to preserve marriages between Spaniards, it also had a vested interest in colonizing the New World and realized that allowing Spanish men to marry indigenous women might encourage them to settle down and establish ties to certain regions. The Catholic Church generally supported, or at least did not oppose, such marriages; the Church hoped the marriages would facilitate the conversion of native people to Christianity and decrease the number of informal unions, which it considered sinful. Therefore, starting in the 1530s, Spain issued policies to encourage single Spanish men in Spanish America to wed. For example, a 1539 royal decree stated that encomiendas could only be given to married men and some posts in the local government were restricted in a similar way. Although it was more common for Spaniards to live with native women out of wedlock, some conquerors and colonists did marry indigenous women, most of them of noble descent.
These unions also helped to consolidate Spanish colonial rule because how do you create an empire thousands of miles away without a standing army? You promote kinship ties between members of the indigenous nobility and Spanish families. Because that is going to produce a population of mixed ancestry that is going to tend to identify, at least in part, with Spanish ways and Spanish culture. And forging such a population was a strategy of the Spanish Crown very early on. [The crown] ordered that the children of these unions live in Spanish households and be raised in Spanish ways. - María Elena Martínez, author of Genealogical Fictions
The Sistema de Castas
As late as 1570, Spanish households in the New World numbered only 25,000 and were surrounded by a vastly greater native population. To preserve their wealth, power, and privileges, the Spanish created a caste-like system, the "Sistema de Castas," with Spaniards in the top group. Others were ranked below based on their percentage of Spanish blood. The child of a Spaniard and indigenous person, for example, was called a mestizo, while the child of a mestizo and a Spaniard was called a castizo.
This system of classification, which sought to determine access to certain rights, professions, and institutions on the basis of ancestry, also accounted for Africans, most of whom were brought to the New World as slaves by the Spanish. Not all people of African descent were slaves, but Spaniards tended to associate them with bondage and tried to keep them in the bottom levels of society. By the last third of the 16th century, Africans and their descendents began having children with Spaniards, as well as with indigenous people, leading to the production of more casta categories. For example, the system classified a child of an African and a Spaniard as a mulatto. A Spaniard and a mulatto produced a morisco, and so forth. The system eventually expanded to include numerous categories, although legally only a few were used and both the number of classifications and terms used varied by period and region.
In 18th-century central Mexico, this complex system of ethnic classification inspired the creation of casta paintings that illustrated where each person in the New World ranked in the system. That the paintings were popular in Spain and other parts of Europe and also had a local audience indicated the growing fascination with race and "intermixing" in the early modern Atlantic world. They also reflected the Spaniards' sense of racial superiority by illustrating an orderly hierarchical society where socio-economic status depended on skin color.
Some paintings depicted the supposed favorable and unfavorable temperaments and characteristics that would result from specific mixtures of blood. For example, according to one painting from the time, a mestizo (50% Spanish blood) was considered "generally humble, tranquil, and straightforward." Another painting states, "From Lobo and Indian woman, the Cambujo is usually slow, lazy, and cumbersome." Ultimately, the casta paintings are troubling reminders of the Spanish colonial racial biases that linked descent, skin color, social status, and behavior. Paradoxically, they also attest to how impractical the system of classification eventually became.
With time, as more castas reproduced with each other, it became harder and harder to determine a person's proportion of Spanish, indigenous, and African blood. It becomes less and less feasible and that's very clear by the 18th century. So the time when more categories surfaced and the casta paintings emerged (the eighteenth century) was precisely the moment when the classification system had in many ways become unfeasible. - María Elena Martínez
The Power, Instability, and Legacies of Bloodlines
As in Spain, the concept of purity of blood served to determine political, economic, and social privilege in the New World. The system of social order was enforced by a series of laws that restricted who could hold office, bear arms, attend the university, and wear certain clothing, among other things. Even among those of Spanish blood, there were distinctions by place of birth. Those who were born in Spain (peninsulares) considered themselves superior to those born in the New World (criollos) and Spanish policies favored the former for the most important political and ecclesiastic appointments.
In practice, however, the system was never as rigid as those in power may have wanted it to be. In indigenous towns, for example, the descendants of the pre-Hispanic nobility could hold office in local government and enjoy other honors and privileges. Some mestizos (whose legal and social status had been ambiguous from the start) were also able to access institutions that had purity of blood requirements, in some cases because they descended from nobles, in others because they received royal dispensations. Furthermore, casta classifications could be manipulated or changed through a variety of means, including moving to a town where one's family origins were unknown, wearing certain types of clothing, speaking Spanish, "marrying up," and falsifying genealogical documents or birth records. Wealth and piety were additional factors that could affect the way neighbors and the community as a whole perceived someone's race.
In short, although colonial Spanish American society tried to create a rigid relationship between ancestry and class, in practice the system was more fluid, especially as time went by and it became more and more difficult to establish a person's ancestry. By 1650, people of mixed ancestry outnumbered the Spanish population in various parts of Latin America and in the 18th century their number continued to increase.
After independence from Spain in the early 19th century, Spanish American countries officially abolished the casta system and slavery. (Cuba and Puerto Rico, which remained under Spanish control until 1898, were the last of the former Spanish colonies to end slavery.) Although authoritarianism, rule by a small group of elites, and political struggles between liberals and conservatives plagued the new nations for at least a half century after independence, in theory they were democracies and established either presidential or parliamentary governments. Republican forms of government and democratic principles of equality were incompatible with a system of rights and privileges based on blood. Nevertheless, the structures, racial ideologies, and forms of discrimination that developed under Spanish colonial rule were hard to dismantle, even as people of indigenous and African descent fought long and hard to claim their rights and carve a political place for themselves in the new nations. Although there were important exceptions, among them Benito Juárez (a Zapotec from Oaxaca who served as president of Mexico, intermittently, from 1858 to 1872), political elites in the region tended to be creoles—descendants of Europeans—and to espouse notions of white superiority. During the last third of the 19th century, Latin America's liberal leaders generally saw indigenous people as obstacles to their economic development and modernization projects and believed that the mixing of populations led to racial degeneration. Several countries, most notably Argentina, tried to attract European immigrants to help "whiten" and "civilize" their populations to be on path towards "progress."
Not until about the 1930s did Spanish America start to seriously challenge the racist ideas inherited from colonialism, ideas reinforced by the "scientific" racism that surfaced in late-nineteenth century Europe and spread to other parts of the world. Intellectuals, writers, and political leaders in Mexico, Peru, and elsewhere led ideological, cultural, and educational movements that embraced the indigenous foundations and mestizo heritage of their nations, thus turning colonial racial ideology on its head.
Despite these important movements, racial attitudes and discrimination in Latin America did not disappear and neither did the strong relationship between race and class. In the last two decades, scholars and intellectuals have increasingly criticized ideologies of mestizaje for reproducing colonial notions of purity and mixture, for not paying enough attention to the difficult socioeconomic plight of indigenous people today, and for more often than not concealing the important role that people of African descent and other populations have played in many parts of Latin America.