The Anglo-Ethiopian Society

Lecture - Wednesday 9th November 2011

Human Genetic Diversity in Ethiopia, its origin and implication

Given by - Neil Bradman

Reviewed by - Anne Parsons

Dr Neil Bradman is Chair of The Centre for Genetic Anthropolgy (TCGA) at University College, London. For over ten years, with colleagues at Addis Ababa University, he has undertaken research on the distribution of human genetic diversity among the peoples of Ethiopia. The talk started with a brief explanation of the elementary biology of genetics so that we could understand some of the more complex ideas and findings that followed.

Neil told us that Ethiopia is the most genetically diverse area in the world, with diversity decreasing with distance from Addis Ababa. This fact surprised many of the audience. Neil explained that this could be accounted for by the fact that when humans left Ethiopia approximately 80,000 years ago to populate the rest of the world only a relatively small number of the total population went and they left behind a much bigger gene pool in sub-Saharan Africa. This did not prove, however, that humans originated in Ethiopia, as earlier migration to Ethiopia from different parts of Africa could have occurred.

A large area of scientific interest and research has concerned the effects that genetics may have on drug therapy. Many medicinal drugs are metabolised by liver enzymes (to convert them to active substances or to break active molecules down ready for excretion) and activity of these enzymes can be genetically controlled. For instance, tacrolimus, an immunosuppressant used by transplant patients, is metabolised to largely inactive compounds. African peoples generally have an increased activity of the enzyme necessary for this and therefore may respond less well than other populations to treatment.

It is unlikely that it will be economically viable to investigate individuals for their genetic susceptibility to drug therapy although choice of drug based on ethnicity may be possible.

Another interesting line of research has involved the Ari people, where agricultural workers form the dominant group with blacksmiths, potters, and weavers traditionally facing discrimination. Mitochondrial DNA (passed down through the maternal line) indicated that the agriculturists were distinct from the blacksmiths and potters; but comparison with Y-chromosome (passed down through the paternal line) showed blacksmiths and agriculturists being more closely linked and potters being distinct. The most likely explanation for this is that the Y chromosome tends to travel from the dominant to the less dominant.

Overall, a fascinating, and highly complex area and we thank Neil very much for his presentation.

First Published in News File Spring 2012

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