What makes us different? What differentiates us from our neighbors, our friends or strangers from distant countries? For years we know that there are genetic differences among different human populations that contribute to their appearance and to a different susceptibility to disease. These small genetic differences between healthy individuals are called “polymorphisms”. The group of Manel Esteller, director of the Programme of Epigenetics and Cancer Biology at the Institute for Biomedical Research of Bellvitge, ICREA researcher and professor of genetics at the University of Barcelona, described today in the prestigious international biomedical journal Genome Research the existence of epigenetic differences between different human populations. That is to say, we are not only different by our DNA (genome) but also by the different regulation of this DNA (epigenome).

“We have studied the epigenomes of three hundred healthy individuals of three large human populations (United States Caucasians, Asians of the chinese ethnic group Han and sub-Saharan Africans) and we have found epigenetic differences that allows us to identify each group of humans”- explains Manel Esteller -“There are genes that are more or less active (due to different levels of the epigenetic mark called DNA methylation) according to the studied population group. The target genes of these differences between humans are found in all the cellular pathways, but it is worth noting those related with the pigmentation of the skin and the different resistance to infections due to various pathogenic microorganisms, such as the virus (Hepatitis B and HIV) and bacteria (Escherichia coli and Shigella). This latter finding would help to explain the different tendency to develop a disease among people of different geographic origin.”

The discovery has important implications for explaining the richness and diversity of the different human populations that can no longer be attributed only to a different genome, but also to a different epigenome. The speed and reversability of the epigenetic changes in the genome could also explain how occur the necessary changes in our cells and tissues when populations migrate from one territory to another. In evolutionary terms it provides clues to understand the rapid adaptation to the environment of the first humans who dispersed from the Horn of Africa all over the planet.