That would fit rather nicely with Bartoshuk's finding that there exists a subset of PROP-tasters supersensitive to bitterness. She calls them super-tasters. Looking at the three groups, you see just the sort of patterns you'd expect for a recessive gene. The distribution is slightly sex-skewed. What's fascinating, says Bartoshuk, is that tongue anatomy spells out the differences among these groups.
Tasters have more taste buds than nontasters, and super-tasters have the most.
Because taste buds are surrounded by nerve endings that sense not only taste but pain and touch, super-tasters, perhaps not surprisingly, have a more sensational taste repertoire. Bitter tastes bitterer, salt a bit saltier, sour sharper, and some sweets sweeter. Fat feels fattier, gums thicker, and alcohol and chili burn more fiercely. But because the super-tasters' sensory realms are so intense, they may avoid strong tastes especially bitter ones like grapefruit, coffee, beer, or broccoli and thus actually shrink their dietary horizons. Intrigued by her discoveries, I persuaded Bartoshuk to let me visit her lab for a two-day immersion in taste.