One of the results of the movement of people between New and Old Worlds were cultural exchanges. For example, in the article "The Myth of Early Globalization: The Atlantic Economy, 1500–1800", Pieter Emmer makes the point that "from 1500 onward, a 'clash of cultures' had begun in the Atlantic". This clash of culture involved the transfer of European values to indigenous cultures. As an example, the emergence of the concept of private property in regions where property was often viewed as communal, concepts of monogamy (although many indigenous peoples were already monogamous,) the role of women and children in the social system, and the "superiority of free labor," although slavery was already a well-established practice among many indigenous peoples. Another example included the European deprecation of human sacrifice, an established religious practice among some indigenous populations.