Changing where and how we live affects the expression of genes that control the immune response and body growth, according to research by the Faculty of Medicine and the Institut Pasteur in France.
The study, published in Nature Communications, examined DNA methylation of two populations in Central Africa. Methylation — in which a molecule of carbon and hydrogen binds to DNA — acts as a “dimmer switch” on genes, affecting whether or how much a gene is expressed. The study of these switches, known as epigenetics, has exploded in the past decade, as its role in human development and health has become more apparent.
Michael Kobor
The scientists, including a group led by Canada Research Chair Michael Kobor, looked at two populations in Central Africa with different lifestyles and habitats: Pygmies, who are nomadic hunter-gatherers living in forests, and Bantu, settled farmers in urban, rural or forest habitats. These two populations separated approximately 60,000 years ago. The scientists also investigated a particular group of Bantu farmers sharing the same forest environment as Pygmies.
The scientists began by comparing the level of genomic methylation in this specific group of forest-dwelling Bantu with that of urban or rural Bantu. They observed that the recent change in habitat had resulted in changes in methylation that mainly affected the functions of the immune system.
The scientists also examined the impact of their lifestyles — the Bantu are farmers, while the Pygmies are hunter-gatherers. The scientists identified differences in the epigenome relating to development, such as size and bone mineralization, which affected the physical characteristics that distinguished Bantu from Pygmies.
Although epigenetic changes such as DNA methylation can be strongly affected by the environment, they are not passed on from generation to generation. However, they can become hereditary when they are controlled by a mutation in the DNA.
“This is a great example of how we can take natural experiments — making use of the variety of human migration and settlements, for example — and incorporate epigenetic research to discover fundamental principles affecting health and disease,” says Dr. Kobor, a Principal Investigator at the Centre for Molecular Medicine and Therapeutics and a Scientist at the Child and Family Research Institute.