An autosomal DNA study (2011), with nearly 1000 samples from all over the country ("whites", "pardos" and "blacks", according to their respective proportions), found a major European contribution, followed by a high African contribution and an important Native American component. "In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South". The 2011 autosomal study samples came from blood donors (the lowest classes constitute the great majority of blood donors in Brazil), and also public health institutions' personnel and health students. The study showed that Brazilians from different regions are more homogenous than previously thought by some based on the census alone. "Brazilian homogeneity is, therefore, a lot greater between Brazilian regions than within Brazilian regions".