John ‘JB’ Clegg is a molecular biologist whose research into haemoglobin — the protein in blood that carries oxygen from the lungs to the rest of the body — has improved our understanding of population genetics and the spread of malaria. John focuses his work on thalassemia, an inherited blood disorder that results in the production of less haemoglobin and fewer red blood cells.

Using modern molecular tools for genetic analysis to study the distribution of thalassemia in populations, John demonstrated that although this blood defect can cause an overload of iron, bone deformities and cardiovascular illness, people carrying a single gene for thalassemia also have increased protection against some forms of malaria.

The World Health Organization estimates that at least five per cent of the world’s population carries a thalassemia gene. John’s research suggests that natural selection has improved the success of these individuals and thus increased the occurrence of this genetic trait in malarial regions of the world.