The Colombian town of Tuquerres, nestled high in the Andes Mountains, has one of the highest rates of stomach cancer in the world: about 150 cases per 100,000 people. Meanwhile in the coastal town of Tumaco, just 200 kilometres away, the equivalent rate is only around 6 in 100,000.
This 25-fold difference is partly due to an evolutionary mismatch between human and microbe, according to a new study.
The main cause of stomach cancer is Helicobacter pylori, a bacterium that infects half the world’s population. It is usually harmless, but occasionally leads to tumours. In places such as South America, the arrival of European colonists has broken this long history of co-evolution, leaving some people with H. pylori strains that do not share their ancestry.
Read the full, original story: Human–microbe mismatch boosts risk of stomach cancer