Genetic Ancestry of Americans Is More Complex Than Previously Thought, Study Shows By Nayomi Chibana | Mar 25, 2015 12:16 PM EDT Although the Americas has long been characterized as a melting pot of different racial and ethnic groups, the extent to which this is true is just beginning to be revealed. A recent Oxford University study has found that the genetic profile of Americans is much more complex than previously thought. By analyzing more than 4,000 previously collected DNA samples from 64 different populations in Europe, Africa and the Americas, researchers were able to reveal the genetic fingerprints of the slave trade and colonization - and uncover events that the history books overlooked. Scientists found, for example, that while Spaniards provide the majority of European ancestry in continental American Hispanic populations, the most common European genetic source in African-Americans and Barbadians is from the Britain. Additionally, it was revealed that the ancestors of the current-day Yoruba people from West Africa provided the most significant contribution of genes from Africa to all present-day American populations. The study also concludes that the Basques, an ethnic group that currently resides in Spain and France, provided a small but distinct genetic contribution to continental South American populations, including the Maya in Mexico. "The differences in European ancestry between the Caribbean islands and mainland American population that we found were also previously unknown. It is likely that these differences reflect different patterns of migration between the Caribbean and mainland America," said study leader Professor Cristian Capelli from the Department of Zoology at Oxford University. The DNA samples used in the study were collected from individuals in Barbados, Colombia, the Dominican Republic, Ecuador, Mexico, Puerto Rico and African-Americans in the United States. The researchers used a technique called haplotype-based analysis to compare the pattern of genes in the "donor" African and European populations with "recipient" American populations to trace where the ancestors of present-day North and South Americans came from. The team hopes to use the same approach to study other populations with diverse genetic contributions, such as the Brazilians.