Scientists studying subtle variations in people's taste-bud genes have found evidence that early humans benefited from a random mutation that enhanced their sensitivity to bitter flavors.
Bitterness is one of five tastes that humans can detect. Sensitivity to bitterness can help minimize the odds of getting poisoned, because many natural toxins, including cyanide-based chemicals that plants produce to protect themselves against insects and other predators, are naturally bitter.
A team of researchers from Britain, Germany and the United States looked at variations in a gene that controls bitterness recognition -- variations that make some people more sensitive to bitter tastes than others. An analysis of the global distribution of those gene variants in 997 people from 60 ethnic populations around the world suggested that a version of the gene that makes people extra sensitive to bitterness first arose in Africa as the result of a random mutation about 400,000 years ago.
That version gradually became the dominant form, suggesting it offered people a survival advantage, the team reported in a recent issue of Current Biology. At the time the gene arose, they reason, early humans were hunter-gatherers and probably would have benefited from an enhanced ability to avoid toxic plants.
Interestingly, they note, the supersensitive version is less prevalent among people living in parts of Africa where malaria is prevalent.