Mice fed a diet of McDonald's burgers and fries not only put on weight but start to develop human-like genetic traits, scientists have found.
The same effect is not seen when mice are given a typical chimpanzee diet of raw fruit and vegetables.
Most of the changes seen in the mice occurred in the liver, where a number of genes linked to metabolism became more active.
According to researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, the findings support the theory that food choices helped to make us human.
Although humans and chimps evolved from the same ancestor, they have very different diets.