HLA in anthropology: the enigma of Easter Island

In this article, we first present four significant cases where human leukocyte antigen (HLA) studies have been useful for the reconstruction of human peopling history on the worldwide scale; i.e., the spread of modern humans from East Africa, the colonization of East Asia along two geographic routes, the co-evolution of genes and languages in Africa, and the peopling of Europe through a main northward migration. These examples show that natural selection did not erase the genetic signatures of our past migrations in the HLA genetic diversity patterns observed today. In the second part, we summarize our studies on Easter Island. Using genomic HLA typing, we could trace an introduction of HLA alleles of native American (Amerindian) origin to Easter Island before the Peruvian slave trades; i.e., before the 1860s, and provide suggestive evidence that they may have already been introduced in prehistoric time. Our results give further support to an initial Polynesian population of the island, but also reveal an early contribution by Amerindians. Together, our data illustrate the usefulness of typing for HLA alleles to complement genetic analyses in anthropological investigations.